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Wireless Energy Transfer System with Multiple Coils via Coupled Magnetic Resonances
Sanghoon Cheon,Yong-Hae Kim,Seung-Youl Kang,Myung-Lae Lee,Taehyoung Zyung 한국전자통신연구원 2012 ETRI Journal Vol.34 No.4
A general equivalent circuit model is developed for a wireless energy transfer system composed of multiple coils via coupled magnetic resonances. To verify the developed model, four types of wireless energy transfer systems are fabricated, measured, and compared with simulation results. To model a system composed of n-coils, node equations are built in the form of an n-by-n matrix, and the equivalent circuit model is established using an electric design automation tool. Using the model, we can simulate systems with multiple coils, power sources, and loads. Moreover, coupling constants are extracted as a function of the distance between two coils, and we can predict the characteristics of a system having coils at an arbitrary location. We fabricate four types of systems with relay coils, two operating frequencies, two power sources, and the function of characteristic impedance conversion. We measure the characteristics of all systems and compare them with the simulation results. The flexibility of the developed model enables us to design and optimize a complicated system consisting of many coils.
Binary Power Amplifier with 2-Bit Sigma-Delta Modulation Method for EER Transmitter
Jiyoun Lim,Sanghoon Cheon,Kyeong-Hak Kim,홍성철,Dong-Wook Kim 한국전자통신연구원 2008 ETRI Journal Vol.30 No.3
A novel power amplifier for a polar transmitter is proposed to achieve better spectral performance for a wideband envelope signal. In the proposed scheme, 2-bit sigma-delta (ΣΔ) modulation of the envelope signal is introduced, and the power amplifier configuration is modified in a binary form to accommodate the 2-bit digitized envelope signals. The 2-bit ΣΔ modulator lowers the noise of the envelope signal by fine quantization and thus enhances the spectral property of the RF signal. The Ptolemy simulation results of the proposed structure show that the spectral noise is reduced by 10 dB in a full transmit band of the EDGE system. The dynamic range is also enhanced. Since the performance is improved without increasing the over-sampling ratio, this technique is best suited for wireless communication with high data rates.
Evaluation of 1/f Noise Characteristics for Si-Based Infrared Detection Materials
Hojun Ryu,Sanghoon Cheon,Seong Mok Cho,Woo Seok Yang,Chang Auck Choi,Sein Kwon 한국전자통신연구원 2009 ETRI Journal Vol.31 No.6
Silicon antimony films are studied as resistors for uncooled microbolometers. We present the fabrication of silicon films and their alloy films using sputtering and plasma-enhanced chemical vapor deposition. The sputtered silicon antimony films show a low 1/f noise level compared to plasma-enhanced chemical vapor deposition (PECVD)-deposited amorphous silicon due to their very fine nanostructure. Material parameter K is controlled using the sputtering conditions to obtain a low 1/f noise. The calculation for specific detectivity assuming similar properties of silicon antimony and PECVD amorphous silicon shows that silicon antimony film demonstrates an outstanding value compared with PECVD Si film.
내진 성능을 갖춘 고성능 버터플라이밸브의 성능 인증을 위한 구조 및 유동해석
나도경(Dokyeong Na),김상훈(Sanghoon Kim),김경현(Kyeoghyeon Kim),박천(Cheon Park),도재혁(Jaehyeok Doh),임승완(Seungwan Lim) 한국신뢰성학회 2021 신뢰성응용연구 Vol.21 No.4
Purpose: Generally, the operating period of existing butterfly valves is 3 to 6 months, with continuous maintenance and replacement. It is necessary to develop a butterfly valve with high performance that increases the facility"s efficiency and water treatment capacity and ensures reliability that it can be used even in an adverse vibrating environment. Methods: This study investigates the structural safety of the new valve with the conventional valve through structural analysis. Furthermore, the cavitation occurrence and flowability are investigated based on flow analysis according to the valve"s opening rate. Results: When comparing the existing model with the new model by performing structural and flow analysis, it was found that the structural stability, improved flowability, and the degree of cavitation were reduced effectively. Conclusion: Based on these results, applying the proposed design can efficiently reduce the overseas dependence of the industry of domestic butterfly valves and can also be applied for other developing related products and industries.
Core–shell strain structure of zeolite microcrystals
Cha, Wonsuk,Jeong, Nak Cheon,Song, Sanghoon,Park, Hyun-jun,Thanh Pham, Tung Cao,Harder, Ross,Lim, Bobae,Xiong, Gang,Ahn, Docheon,McNulty, Ian,Kim, Jungho,Yoon, Kyung Byung,Robinson, Ian K.,Kim, Hyunju Nature Publishing Group 2013 Nature materials Vol.12 No.8
Zeolites are crystalline aluminosilicate minerals featuring a network of 0.3–1.5-nm-wide pores, used in industry as catalysts for hydrocarbon interconversion, ion exchangers, molecular sieves and adsorbents. For improved applications, it is highly useful to study the distribution of internal local strains because they sensitively affect the rates of adsorption and diffusion of guest molecules within zeolites. Here, we report the observation of an unusual triangular deformation field distribution in ZSM-5 zeolites by coherent X-ray diffraction imaging, showing the presence of a strain within the crystal arising from the heterogeneous core–shell structure, which is supported by finite element model calculation and confirmed by fluorescence measurement. The shell is composed of H-ZSM-5 with intrinsic negative thermal expansion whereas the core exhibits a different thermal expansion behaviour due to the presence of organic template residues, which usually remain when the starting materials are insufficiently calcined. Engineering such strain effects could have a major impact on the design of future catalysts.
Early response in macrophages by exposure to a low concentration of anthrax lethal toxin
정경화,JeongAh Nam,Ji Cheon Kim,Seoung Joo Kim,Kwang Gun Oh,Sanghoon Kim,채영규 대한독성 유전단백체 학회 2011 Molecular & cellular toxicology Vol.7 No.1
The central role in the pathogenesis of anthrax is played by the two classical anthrax toxins. Three factors that are secreted by the bacterium combine to form two bipartite toxins. Edema toxin, consisting of the protective antigen (PA) and the edema factor (EF), causes the edema associated with anthrax infection. Lethal toxin (LeTx), composed of PA and the lethal factor (LF), is believed to be responsible for causing death in systemic anthrax infections. LF is a zinc-dependent endoproteinase that cleaves the N-terminus of mitogen-activated protein kinase kinases (MAPKKs) and functionally impairs cells of both the innate and adaptive immune systems. To analyze the cellular mechanisms underlying the host-pathogen interaction in anthrax infection, we examined the murine macrophage cell line RAW 264.7 following treatment with a relatively low concentration of LeTx (0.1μg/mL of PA, 0.1 μg/mL of LF). Analysis of the gene expression pattern of macrophages treated with low concentrations of LeTx indicated changes in the expression levels of many genes 90 min after toxin treatment. These genes represent the early response in intoxicated macrophages and may contribute to the identification of survival or death factors. Additionally,we demonstrate that the activation of the putative phosphatase and tensin homology on chromosome 10(PTEN) signal transduction pathway regulates cell death by decreasing the levels of phosphorylated glycogen synthase kinase 3β (GSK-3β) through activation of protein phosphatase 1 catalytic subunit alpha (PP1c)in lethal toxin-intoxicated murine macrophages. Furthermore,genes regulating growth and proliferation,transcription factor genes, and immune responsive genes were differentially expressed as a consequence of lethal toxin-mediated macrophage cytotoxicity.
김연어(Yeoneo Kim),천준석(Junseok Cheon),송동수(Dongsu Song),노상훈(Sanghoon Rho),신승철(Seungcheol Shin),우균(Gyun Woo) 대한전자공학회 2023 대한전자공학회 학술대회 Vol.2023 No.6
Recently, software is becoming more complex as it is widely used in various domains. Therefore, the software verification step is becoming difficult, so it is moving toward using automated testing tools. In this situation, it is getting important to measure the testability using metrics that can represent objectively what code is advantageous for testing. In this paper, we analyze the correlation between the source code metrics and the test coverage of automated testing tools. We measured 75 code metrics through selected 20 open-source projects and analyzed the correlation between these metrics and the coverage which is gained through COYOTE, an automated testing tool. Unfortunately, the existing code metrics and the test coverage show a low correlation. Analyzing the characteristics of the automated testing tool reveals the need for metrics that can represent the complexity of data structure.