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All Journal Jurnal Penelitian Fisika dan Aplikasinya (JPFA) Jurnal Sains Materi Indonesia Indonesian Journal of Electrical Engineering and Informatics (IJEEI) Jurnal Pendidikan MIPA Journal of Engineering and Technological Sciences JFA (Jurnal Fisika dan Aplikasinya) POLYGLOT JOHME: Journal of Holistic Mathematics Education Prosiding Konferensi Nasional PKM-CSR PROSIDING SEMINAR NASIONAL FISIKA (E-JOURNAL)
Sitompul, Henni
Universitas Pelita Harapan
Humanities Astronomy Computer Science & IT Control & Systems Engineering Earth & Planetary Sciences Economics, Econometrics & Finance Education Electrical & Electronics Engineering Energy Engineering Environmental Science Materials Science & Nanotechnology Mathematics Nursing Physics Public Health Social Sciences Other

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Synthesis and Characterization of Ba0.6Sr0.4Fe12O19/LaMnO3 Composites as Microwave Absorbers Yohanes Edi Gunanto; Maya Puspitasari Izaak; Henni Sitompul; Wisnu Ari Adi
Indonesian Journal of Electrical Engineering and Informatics (IJEEI) Vol 9, No 4: December 2021
Publisher : IAES Indonesian Section

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.52549/ijeei.v9i4.3239

Abstract

The synthesis and characterization of Ba0.6Sr0.4Fe12O19/LaMnO3 composite material has been successfully carried out by mechanical alloying method using high energy milling. Crystal structure and surface morphology were characterized using x-ray diffraction and scanning electron microscopy. While the value of magnetization and the ability to absorb microwaves, vibrating sample magnetization and vector network analyzing were used, respectively. With variations in weight, does not change the crystal structure. The Ba0.6Sr0.4Fe12O19phase has a hexagonal structure and the LaMnO3 phase has an orthorhombic structure. Surface morphology has a heterogeneous size in the range of 200-450 nm with the form of platelets. The composite material Ba0.6Sr0.4Fe12O19/LaMnO3 is a hard-soft magnetic material with a magnetic saturation of Ms ~ 46.83 emu/g, Mr ~ 28.8 emu/g, and a coercive field of Hc ~ 3.88 kOe. The minimum reflection loss value is – 13.0 dB at 11.2 GHz frequency and 1.52 GHz bandwidth.
THE STRUCTURAL, IMPEDANCE AND DIELECTRIC A FERRITE CORE OF IRON MANGANITE AND ITS COMPOSITE Yohanes Edi Gunanto; Henni Sitompul; Maya Puspitasari Izaak; Wisnu Ari Adi
Jurnal Sains Materi Indonesia Vol 23, No 1: OCTOBER 2021
Publisher : Center for Science & Technology of Advanced Materials - National Nuclear Energy Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17146/jsmi.2021.23.1.6303

Abstract

THE STRUCTURAL, IMPEDANCE AND DIELECTRIC A FERRITE CORE OF IRON MANGANITE AND ITS COMPOSITE. Samples with single-phase MnFeO3 and multiphase MnFeO3/ZnFe2O4 (30/70), and MnFeO3/ZnFe2O4/LaMnO3 (30/40/30) have been successfully prepared as ferrite cores by the solid-state reaction method using high energy milling. Crystal structure, surface morphology, impedance, AC-conductivity and dielectric quantities, such as dielectric constant and dielectric loss have been studied. The crystalline structures for MnFeO3, ZnFe2O4, and LaMnO3 are hexagonal, cubic and monoclinic, The Rietveld program used for XRD analysis resulted in the composition fractions of single phase MnFeO3, multiphase MnFeO3/ZnFe2O4 (31/69), and MnFeO3/ZnFe2O4/LaMnO3 (31/40/29). The morphology of all samples has a heterogeneous shape and size with low porosity. The single-phase impedance of MnFeO3 is higher than the multiphase sample. The conductivity of the three samples has the same pattern, which is relatively constant at low frequencies and begins to increase at frequencies above 10 kHz. The dielectric constant and dielectric loss (tan ????) have high values at low frequencies, decrease exponentially with increasing frequency and are relatively fixed at high frequencies.
Microwave Absorbing Material of Ba0.95La0.05Fe12-2xZnxTixO19 (x = 0; 0.5; and 1.0) with Broadband Characteristic at X-band Frequency Yohanes Edi Gunanto; Henni Sitompul; Maya Puspitasari Izaak; Yosep Sarwanto; Wisnu Ari Adi
Journal of Engineering and Technological Sciences Vol. 54 No. 2 (2022)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2022.54.2.2

Abstract

In this study, hexaferrite Ba0.95La0.05Fe12-2xZnxTixO19 (x = 0; 0.5; and 1.0) was synthesized and characterized, which can be applied as microwave absorber in the X-band frequency range. It is a potential candidate for a radar absorbing material for microwave absorption, particularly for use in anti-radar paint in the defense sector. Samples were prepared using solid state reaction synthesis with high energy milling. After sintering at the right temperature, the samples were characterized using an X-ray diffractometer (XRD), a scanning electron microscope (SEM), a vibrating-sample magnetometer (VSM) and vector network analysis (VNA). The XRD characterization results indicated that all samples were in phase and had a hexagonal lattice structure with a P63/mmc space group and a crystallite size between 38 and 45 nm. The surface morphology of the characterization results using SEM showed a heterogeneous particle shape with particle sizes ranging from 140 to 200 nm. Substitution of Ti4+ ions for Fe3+ ions by Zn2+ ions resulted in a decrease of the magnetic saturation (Ms), the magnetic remanence, and the sample’s coercivity field. With a sample thickness of 1.5 mm, the VNA results confirmed that the ability to absorb microwaves and bandwidth will increase along with increase of the substitution value x. The reflection loss value was about -13.3 dB at a frequency of around 11 GHz, with a bandwidth of 1.4 GHz for the sample with x = 1.0 composition.
Synthesis and Corrosion Test of Magnesium Zinc-5% Hydroxyapatite (MgZn-5% wt.Hap) Biocomposites as a Bone Biodegradable Implant Material Henni Sitompul; Kiagus Dahlan; Deni Noviana; Marzuki Silalahi; Sulistioso Giat Sukaryo; Yohanes Edi Gunanto
Jurnal Fisika dan Aplikasinya Vol 15, No 1 (2019)
Publisher : Lembaga Penelitian dan Pengabdian Kepada Masyarakat, LPPM-ITS

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (904.498 KB) | DOI: 10.12962/j24604682.v15i1.3797

Abstract

In recent years, development of magnesium (Mg) as biodegradable implant very rapidly in orthopedic applications. This is due to its young’s modulus close to young modulus of natural bone. However, Mg implants demonstrate higher biological activity which could cause high degradation rate in human bio-environment. Consequently, needed to develop Mg-based alloys with superior corrosion performance. In the present study, it has been attempted to develop biocomposite of Magnesium Zinc-5% Hydroxyapatite (MgZn-5%HAp) as biodegradable bone implant. The biocomposites were prepared by adding 5wt.% powders to MgZn powder and then were sintered at temperature 350 oC in vacuum furnace for holding an hour. The characterization of MgZn-5wt%HAp biocomposite was examined by Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) and X-ray diffraction (XRD) while corrosion tested by potensiostat. The SEM / EDS and XRD results indicated that some of the Zn atoms have dissolved in Mg to form a MgZn solid solution. The SEM results also showed that the MgZn-5%HAp biocomposite has a microstructure with a matrix Mg and HAp at the grain boundary. The presence of HAp in the sample resulted in a smaller crystallite size and corrosion rate compared to  the one with MgZn alloy.
Development of magnetic functional materials based on carbon/manganite/ferrite composites for Microwave absorber materials applications Maya Puspitasari Izaak; Yohanes Edi Gunanto; Henni Sitompul; Wisnu Ari Adi
Jurnal Fisika dan Aplikasinya Vol 17, No 2 (2021)
Publisher : Lembaga Penelitian dan Pengabdian Kepada Masyarakat, LPPM-ITS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j24604682.v17i2.8978

Abstract

The synthesis of carbon/manganite/ferrite composite materials for microwave absorber applications has been successfully carried out with variations in the composition of 15:55:30 and 15:45:40 (wt%). This composition was successfully confirmed based on the analysis of the X-ray diffraction pattern using the GSAS program. The refinement results show that each phase of each composite has a good structure. Based on surface morphological observations, it is known that the composite samples have varying particle sizes of around 150-500 nm which are evenly distributed over the entire surface of the sample. The result of the microwave absorption analysis implies that the difference in composition results in a slight increase of the reflection loss and the presence of a new absorption peak at a frequency of 4.36 GHz. Our result underlines that the characteristic of microwave absorption in composites is insignificantly influenced by the composition of the material as the absorption properties are mainly affected by the respective phases that form it, not by the entire phase of the composite.
The synthesis of TiO2 nanoparticles by Milling and Coprecipitation Mixed Method Maya Puspitasari Izaak; Yohanes Edi Gunanto; Henni Sitompul; Wisnu Ari Adi
Jurnal Fisika dan Aplikasinya Vol 16, No 2 (2020)
Publisher : Lembaga Penelitian dan Pengabdian Kepada Masyarakat, LPPM-ITS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j24604682.v16i2.5199

Abstract

Ilmenite type Fe2O3 waste (which is processed from natural iron sand) was processed into TiO2 nanoparticles powder carried out by leaching with HCl and then using high-energy milling (HEM) for 50 hours. The characteristics of the powder such as particle size, size distribution and phases were analyzed using various techniques such as XRD, SEM, EDS and particle size analyzer. Synthesis and characterization of ilmenite type iron sand have been successfully made into TiO2 by milling and coprecipitation mixed method. The purity level of TiO2 was obtained by 85.01%. Particle size of TiO2 was approximately 500 nm.
Effect of HAp on Characterization of MgZn-xHAp Biocomposites Henni Sitompul; Yohanes Edi Gunanto; Maya Puspitasari Izaak
Jurnal Fisika dan Aplikasinya Vol 17, No 1 (2021)
Publisher : Lembaga Penelitian dan Pengabdian Kepada Masyarakat, LPPM-ITS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j24604682.v17i1.7411

Abstract

Research on Mg as biodegradable materials in orthopedics has been carry out intensively in the 17 years. Various studies conducted to produce material that is superior in mechanical properties and corrosion resistance. One of the developments carry out is to make Mg-based composite. This study aims to see the effect of HAp on Mg6ZnHAp composites. The biocomposites were synthesized by mixing the HAp powder on the Mg6Zn powder mixture with the composition of 5%, 7% and 9% using ball milling for 30 minutes. The material is sintered at 350 oC and held for one hour. Biocomposites were characterized by SEM/EDS, X-ray diffraction (XRD) and Potentiostat. The SEM/EDS results showed that the larger the HAp composition resulted in the smaller grain size. The crystallite size of the material decreases with increasing HAp composition in the material. The presence of HAp in the material also affects the corrosion rate. The greater HAp composition in the material will result in better corrosion resistance. 
PENTINGNYA KOMPETENSI PROFESIONAL BAGI MAHASISWA CALON GURU KRISTEN DALAM KEGIATAN PEMBELAJARAN MATEMATIKA [THE IMPORTANCE OF PROFESSIONAL COMPETENCE FOR PRE-SERVICE CHRISTIAN TEACHERS IN MATHEMATICS LEARNING ACTIVITIES] Ester Putri Febriana; Tanti Listiani; Henni Sitompul
Polyglot Vol 17, No 1 (2021): JANUARY
Publisher : Universitas Pelita Harapan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19166/pji.v17i1.2442

Abstract

Schools are educational institutions that are primarily focused on achieving educational goals. In achieving these goals, schools need competent teachers. Competent teachers are teachers who have four teacher competencies, namely learning management (pedagogical competence), potential development (social competence), academic mastery (professional competence), and personality attitudes (personality competence). A teacher must possess these four teacher competencies in order to support his/her role as an educator. Based on the field experience program conducted by pre-service teachers, it is evident that pre-service teachers lack professional competence. The purpose of writing this paper is to further examine the importance of professional competence for pre-service teachers in supporting the ongoing learning activities at a school, especially for a Christian teacher. The importance of professional competence for a pre-service teacher can provide confidence when teaching, the capacity to guide in mathematics learning activities, and the ability to carry out his/her role as a restoration agent. To improve professional competence, teachers should conduct microteaching activities, study, and attend seminars and other benefical activities.BAHASA INDONESIA ABSTRACT: Sekolah merupakan lembaga pendidikan yang paling utama berfokus kepada pencapaian tujuan-tujuan pendidikan. Dalam mencapai tujuan pendidikan yang telah ditetapkan, sekolah membutuhkan seorang guru yang berkompeten. Guru yang berkompeten adalah guru yang memiliki empat kompetensi guru yaitu pengelolaan pembelajaran (kompetensi pedagogi), pengembangan potensi (kompetensi sosial), penguasaan akademik (kompetensi profesional), dan sikap kepribadian (kompetensi kepribadian). Keempat kompetensi guru tersebut haruslah dimiliki oleh seorang guru agar dapat mendukung perannya sebagai seorang pendidik. Berdasarkan program pengalaman lapangan yang telah dilakukan oleh mahasiswa calon guru, dapat dilihat bahwa mahasiswa calon guru masih kurang dalam kompetensi profesional. Tujuan penulisan paper ini untuk mengkaji tentang pentingnya kompetensi profesional bagi seorang mahasiswa calon guru dalam mendukung kegiatan pembelajaran yang sedang berlangsung di sekolah, terutama dalam diri seorang guru Kristen. Pentingnya kompetensi profesional bagi seorang mahasiswa calon guru, yaitu memberikan rasa percaya diri ketika mengajar, guru dapat menjadi penuntun dalam kegiatan pembelajaran matematika, serta guru dapat menjalankan perannya sebagai agen restorasi. Dalam meningkatkan kompetensi profesional, guru disarankan untuk dapat melakukan kegiatan microteaching, belajar, mengikuti seminar dan kegiatan-kegiatan yang dapat meningkatkan kompetensi tersebut.
GURU KRISTEN SEBAGAI PENUNTUN BELAJAR SISWA KELAS XII DI SATU SEKOLAH KRISTEN [CHRISTIAN TEACHERS AS GUIDES TO LEARNING FOR GRADE 12 STUDENTS AT ONE CHRISTIAN SCHOOL] Ester Lusia Gultom; Henni Sitompul; Kimura Patar Tamba
JOHME: Journal of Holistic Mathematics Education Vol 3, No 1 (2019): DECEMBER
Publisher : Universitas Pelita Harapan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19166/johme.v3i1.1966

Abstract

The implementation of the 2013 curriculum aims to improve the quality of Indonesian education by enabling students to develop competencies. Therefore, it is expected that students actively learn in the classroom so that effective learning processes are created to develop student competencies.  However, based on facts found in grade 12 at one of the Christian schools in Cibubur, students were not actively studying in class. Christian teachers see this gap as something that can be corrected with competencies they can guide. God calls Christian teachers to guide students who have fallen into sin to return to God's path with the proper competence, direction, and purpose. Thus, the purpose of this paper is to present the role of a Christian teacher as a guide to learning for grade 12 students in one Christian school, as well as the resulting impact. The results of this paper about the role of Christian teachers as guides, who view students as precious and personal creations before the Lord, show that teachers are able to guide according to the needs of students using the Discovery Learning model and supporting methods such as group discussion methods, lectures, FAQs, and games. Suggestions aimed at Christian teachers may provide learning guidance for using the Discovery Learning model and its supporting methods.BAHASA INDONESIA ABSTRAK: Penerapan kurikulum 2013 bertujuan untuk meningkatkan kualitas pendidikan Indonesia dengan cara memampukan siswa untuk mengembangkan kompetensi. Oleh karena itu, diharapkan siswa bisa aktif belajar di kelas sehingga dapat diciptakan proses pembelajaran yang efektif untuk mengembangkan kompetensi siswa. Namun, berdasarkan fakta yang ditemukan di kelas XII pada salah satu sekolah Kristen di Cibubur, ditemukan siswa yang masih kurang aktif belajar di kelas. Guru Kristen melihat kesenjangan ini sebagai hal yang harus diperbaiki dengan kompetensi yang dimilikinya sebagai penuntun. Karena Tuhan memanggil guru Kristen untuk menuntun siswa yang telah jatuh dalam dosa supaya kembali ke jalan Tuhan, dengan kompetensi, arah, dan tujuan yang benar. Maka, tujuan penulisan paper ini adalah memaparkan peran guru Kristen sebagai penuntun belajar siswa kelas XII di satu sekolah Kristen, serta dampak yang dihasilkan. Hasil paper ini mengenai peran guru Kristen sebagai penuntun yang memandang siswa sebagai ciptaan sekaligus pribadi yang berharga di hadapan Tuhan sehingga guru mampu menuntun sesuai dengan kebutuhan siswa, menggunakan model pembelajaran Discovery Learning serta metode pendukungnya seperti metode diskusi kelompok, ceramah, tanya jawab, dan permainan. Saran ditujukan kepada guru Kristen kiranya dapat memberikan tuntunan belajar yang sesuai dengan kebutuhan salah satunya menggunakan model Discovery Learning serta metode pendukungnya.
PERAN GURU KRISTEN DALAM MENINGKATKAN KEAKTIFAN SISWA PADA PROSES PEMBELAJARAN MATEMATIKA DI SEKOLAH KRISTEN [THE ROLE OF CHRISTIAN TEACHERS IN IMPROVING ACTIVE LEARNING IN MATHEMATICS IN A CHRISTIAN SCHOOL] Gifson Teodorus Sihaloho; Henni Sitompul; Oce Datu Appulembang
JOHME: Journal of Holistic Mathematics Education Vol 3, No 2 (2020): JUNE
Publisher : Universitas Pelita Harapan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19166/johme.v3i2.1988

Abstract

Teachers and students have very important roles in the learning process. The teacher's role is planning and conducting the learning process. Students are required to be actively involved in learning. The success of a teacher in teaching will be determined by how active students are in participating in learning. Students' active learning will show that they really follow the learning process. The results of field observations indicate that student activity is still very low. Students very rarely ask questions, are less enthusiastic, unfocused, and sleepy when the teacher teaches. The purpose of this study is to discuss the role of Christian teachers in increasing student activity in the learning process. The results showed that Christian teachers play a role in increasing student activity in the learning process. Teachers are advised to create learning that is fun and not boring by creating varied learning methods, making teaching aids, and using ice breakers or games.BAHASA INDONESIA ABSTRACT: Guru dan siswa memiliki peran yang sangat penting dalam proses pembelajaran. Guru berperan dalam merencanakan dan melakukan proses pembelajaran. Siswa dituntut untuk dapat terlibat aktif dalam belajar. Keberhasilan seorang guru dalam mengajar ditentukan seberapa aktif siswa dalam mengikuti pembelajaran. Siswa belajar aktif menunjukkan bahwa mereka sungguh-sungguh mengikuti proses pembelajaran. Hasil observasi di lapangan menunjukkan bahwa keaktifan siswa masih sangat rendah. Siswa sangat jarang mengajukan pertanyaan, kurang bersemangat, kurang antusias, tidak fokus, dan mengantuk ketika guru mengajar. Tujuan penulisan ini adalah membahas mengenai peran guru Kristen dalam meningkatkan keaktifan siswa dalam proses pembelajaran. Hasil penelitian menunjukkan bahwa guru Kristen berperan dalam meningkatkan keaktifan siswa pada proses pembelajaran. Peran guru Kristen dalam proses pembelajaran adalah menggunakan metode pembelajaran yang bervariasi, membimbing siswa ketika mengalami kesulitan dalam memahami materi, dan membuat ice breaking. Guru-guru disarankan untuk menciptakan pembelajaran yang menyenangkan dan tidak membosankan dengan membuat metode pembelajaran yang bervariasi, membuat alat peraga, dan membuat ice breaking ataupun games. 
Co-Authors DENI NOVIANA Emiliana Emalallan Ester Lusia Gultom Ester Putri Febriana Gifson Teodorus Sihaloho Kiagus Dahlan Kiagus Dahlan Kurniawati Martha Kurniawati Martha Lia Kristina Sianipar Lia Sianipar Marzuki Silalahi Marzuki Silalahi Maya P Izaak Oce Datu Appulembang, Oce Datu Sulistioso Giat Sukaryo Sulistioso Sulistioso Tamba, Kimura Patar Tanti Listiani Wisnu Ari Adi Wisnu Ari Adi Wisnu Ari Adi Wisnu Ari Adi Wisnu Ari Adi Yohanes E Gunanto Yohanes Edi Gunanto Yosep Sarwanto Yustinus Purwamargapratala