• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.789-793
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• 2021

A lithium secondary battery is the most promising candidate for future energy storage devices. On the other hand, the battery capacity decreases gradually due to the small amount of water and decomposition of the salts during the charging and discharging process, which deteriorates at high temperatures. Many researchers focused on increasing the cycling performance, but there have been few studies on the fundamental problem that removes water and HF molecules. In this study, silane molecules that are capable of absorbing water and HF molecules are introduced to the separator. Firstly, silica-coated amino-silane (APTES, 3-aminopropyltriethoxysilane) was synthesized, then the silica reacted with epoxy-silane, GPTMS ((3-glycidyloxypropyl)trimethoxysilane). A ceramic-coated separator was fabricated using the silane-coated silica, which is coated on porous polyethylene substrates. FT-IR spectroscopy and TEM analysis were performed to examine the chemical composition and the shape of the silane-coated silica. SEM was performed to confirm the ceramic layers. LMO half cells were fabricated to evaluate the cycling performance at 60 ℃. The cells equipped with a GPTMS-silica separator showed stable cycling performance, suggesting that it would be a solution for improving the cycling performance of the Li-ion batteries at high temperatures.

• Applied Chemistry for Engineering
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• v.33 no.5
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• pp.496-501
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• 2022

In this study, an anode material for lithium secondary batteries was manufactured using petroleum-based residual oil, which is a petroleum refining by-product. Among petroleum-based residual oils, pyrolysis fuel oil (PFO), fluidized catalyst cracking-decant oil (FCC-DO), and vacuum residue (VR) were used as carbon precursors. The physicochemical characteristics of petroleum-based residual oil were confirmed through Matrix-assisted laser desorption/ionization Time-of-Flight (MALDI-TOF) and elemental analysis (EA), and the structural characteristics of anode materials manufactured from residual oil were evaluated using X-ray crystallography (XRD) and Raman spectroscopic techniques. VR was found to contain a wide range of molecular weight distributions and large amounts of impurities compared to PFO and FCC-DO, and PFO and FCC-DO exhibited almost similar physicochemical characteristics. From the XRD analysis results, carbonized PFO and FCC-DO showed similar d₀₀₂ values. However, it was confirmed that FCC-DO had a more developed layered structure than PFO in Lc (Length of a and c axes in the crystal system) and La values. In addition, FCC-DO showed the best cycle characteristics in electrochemical characteristics evaluation. According to the physicochemical and electrochemical results of the petroleum-based residual oil, FCC-DO is a better carbon precursor for a lithium secondary battery than PFO and VR.

• Journal of Industrial Convergence
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• v.22 no.7
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• pp.81-91
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• 2024

This study was conducted to determine the status of allergic diseases and mental health in adolescents, confirm the relationship between allergic diseases and mental health, and provide basic data for developing effective disease management measures for adolescents at the developmental stage. Secondary analysis was performed on the data from the 17^th Youth Health Behavior Online Survey, and complex sample descriptive statistics, cross-tabulation, and logistic regression analysis were performed using the SPSS 26.0 program. As a result of the study, those with one or more allergic diseases were 1.286 times more likely to have stress (B=1.286, p<.000), 1.289 times more likely to be depressed (B=1.289, p<.000), and 1.399 times more likely to have generalized anxiety disorder (B=1.399, p<.000) was highly likely to experience it. Additionally, factors affecting the mental health of adolescents with allergic diseases were gender, economic level, academic performance, drinking experience, and smoking experience. Stress and generalized anxiety disorder were more likely to be experienced by female students, if they had a lower economic level and academic performance, and if they drank alcohol or smoked. Male students were more likely to experience depression if their economic level and academic performance were higher, and if they did not drink alcohol or smoke. Based on these results, we hope to establish a practical approach by establishing effective strategies to manage allergic diseases in adolescents and the mental health conditions that may arise from them.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.106-114
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• 1992

Abstract-Quantitative surface analysis of Co-Ni and Au-Cu alloys by XPS and SIMS was studied. For Co-Ni alloy, quantitative XPS analysis could be done within 1-2% relative error with pure element standards without any correction. For Au-Cu, quantitative XPS analysis was not possible without any correction. But it could be done with standard alloys of various composition within 1-2% relative error. Without standard alloys, Au-Cu alloys could be analyzed by XPS within 10% relative error with pure element standards. For SIMS analysis of Co-Ni alloys, the relative secondary ion yields of Co+/Nit has linear relation with ratio of each composition so that quantitative SIMS analysis was possible for Co-Ni alloys. Preliminary results of XPS round robin test of VAMAS-SCA Japan Project are given.

• Journal of the Korean Society for information Management
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• v.28 no.3
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• pp.295-312
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• 2011

This study conducted time-series analysis on domestic studies related to entrepreneurship for more than last 50 years by integrating the co-word analysis method of intellectual structure analysis into the study of entrepreneurship. The co-word analysis method is a quantitative analysis method to analyze the overall trend of the study and further study topics by visualizing the information between study topics and arranging the topics on two-dimensional plane and the study result showed largely four phases and the direction of the study path. According to the analysis, the study is started at embryonic study phase(third quadrant), the study topic of independent study phase(second quadrant) is a phase to be a settled independent area as a study and the topics of the study include topics of the study reflecting the situation of the times. At growing study phase(first quadrant) study topics which are closely related to the study topic are arranged, and the topics, the center of the study, are positioned at the study topics of maturity phase(4th quadrant).

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.1
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• pp.14-22
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• 1980

The Fourier convolution algorithm is used to reconstruct a 34 density function from projection data sets. The convolved data are then back-projected to obtain a density function. There are several choices of the weighting function for the design of the reconstruction(deblurring) filter. Present Paper reviews the published reconstruction liters theoretically and proposes a new reconstructirm filter design method, considering the problems such as the effects of sampling rate, aliasing, and noise. Several previous reconstructirn filters are compared with the proposed filter by computer simulations.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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• pp.333-340
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• 2000

Dynamic response behaviors of a bridge are examined under seismic excitations in the 2-dimensional directions are examined. A three-dimensional mechanical model is utilized and the corresponding equations of motions are derived to consider the two directional bridge motions due to the randomness residing in the excitation directions. The arbitrary 2-dimensional directions are simulated by applying two independent excitations in the two directions: main direction(longitudinal) ; the additive direction normal to the main (transverse). The rotational superstructure motions due to the spacial motions of the bridge are considered by admitting the deformation of the bearings at supports. The relative displacement to the ground motions and the relative distance between adjacent oscillators are found to be increased by a considerable amount in the case when considering arbitrary directional seismic excitations. It is also found that the piermotions show more complicated behaviors due to the arbitrary seismic directions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.6C
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• pp.763-769
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• 2004

It is known that a bent function corresponds to a perfect nonlinear function, which makes it difficult to do the differential cryptanalysis in DES and in many other block ciphers. In this paper, for an odd prime p, quadratic p-ary bent functions defined on finite fields are given from the families of p-ary sequences with optimal correlation properly. And quadratic p-ary bent functions, that is, perfect nonlinear functions from the finite field F $_{p^{m}}$ to its prime field $F_{p}$ are constructed by using the trace functions. trace functions.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.209-209
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• 2012

전자의 에너지를 측정하기 위한 분석장치는 원자핵물리뿐만 아니라 화학과 생물학 등 다양한 분야에 걸쳐 매우 유용하게 사용될 수가 있다. 특히 최근에 극고속 과학과 관련해서 매우 짧은 펄스인 아토초 펄스의 발생에 대한 특성평가를 위해 매우 중요한 장치로 사용되고 있다. 그 중 VMI (Velocity Map Imaging) 방법은 TOF (Time of Flight) 방법과 유사하지만, CCD 카메라를 추가로 사용하여 이차원 이미지를 얻음으로써 전자의 운동에너지 및 각도 분포에 대한 정보를 얻을 수 있고 또한 전극에 인가되는 전압은 TOF와 달리 매우 높다. 이번 개발에서는 기존의 전극 렌즈의 geometry와 비교해서 VMI Spectrometer 전극 렌즈의 수를 늘려 multi-electrode concept을 도입함으로써 높은 운동에너지(~1000 eV)를 가진 전자들을 MCP detector상에서 imaging 하는데 있어 높은 공간 분해능(resolution)을 갖도록 설계하고, 또한 높은 사양의 MCP detector 및 CCD 카메라를 이용하여 시간 분해능을 높임으로써 아토초 펄스를 이용한 극고속 실험에 이용 가능하도록 제작하였다.

• Electronics and Telecommunications Trends
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• v.27 no.5
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• pp.1-9
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• 2012

탄소 원자가 육각형의 벌집 모양으로 이차원구조체를 이룬 그래핀은 2004년 처음 실험적으로 흑연으로부터 떼어낼 수 있는 방법이 발표되면서 그 존재가 확인되었고 이후 여러 가지 독특하고 우수한 물성들이 속속 발표되면서 많은 연구자들의 주목을 받고 있다. 수많은 그래핀 연구자들은 천연 그래핀뿐만 아니라 대면적의 그래핀을 성장하고 숨겨진 전기적, 광학적 물성을 밝히고 제어하는 기술에 대한 기초 연구로부터 제어된 그래핀의 물성을 이용한 다양한 전자소자 및 광전소자로의 응용 기술에 대해 많은 연구를 진행하고 있다. 본고에서는 최근에 이루어진 그래핀 기반의 전자소자와 광전소자에 관한 연구 동향을 몇 가지 예와 함께 소개하고 ETRI 그래핀소자창의연구실의 연구주제와 앞으로의 연구 방향에 대해 살펴보고자 한다.