• Journal of Digital Convergence
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• v.16 no.7
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• pp.1-8
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• 2018

In Korea, water supply capacity and facility investments had been emphasized around the 1980s. The water pricing have gained focuses in water policy since the 1990s. This study analyzes a water demand and estimates the relation of water demand and other socio-economic variable, using econometric models on the city of Busan. Water price and income are two key elements to explain water demand. Modeling approach using translog function provides better results, and water demand responds positively to population and income. Energy and water prices are negative factors in deciding water demand. It is requested that water pricing needs to reflect more production costs. Alternative approaches such as water saving facilities by household and use of digital water information should be emphasized for efficient water management in a local community.

• Korean Chemical Engineering Research
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• v.56 no.4
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• pp.561-567
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• 2018

In this study, the electrochemical characteristics of Silicon/Carbon anode materials were analyzed to improve the cycle stability of silicon as an anode materials of lithium ion battery. Porous silicon was prepared from TEOS by the $st{\ddot{o}}ber$ method and the magnesiothermic reduction method. Silicon/Carbon anode materials were synthesized by varying the mass ratio between porous silicon and pitch. Physical properties of the prepared Silicon/Carbon anode materials were analyzed by XRD and TGA. Also the electrochemical performances of Silicon/Carbon anode materials were investigated by constant current charge/discharge, rate performance, cyclic voltammetry and electrochemical impedance tests in the electrolyte of $LiPF_6$ dissolved in organic solvents (EC : DEC = 1 : 1 vol%). The Silicon/Carbon anode composite (silicon : carbon = 5 : 95 in weight) has better capacity (453 mAh/g) than those of other composition cells. The cycle performance has an excellent capacity retention from 2nd cycle to 30th cycle.

• The Journal of the Acoustical Society of Korea
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• v.31 no.8
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• pp.514-522
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• 2012

The temperature dependence of the characteristics in a PZT-5 piezoelectric ceramic vibrator with the transverse mode was investigated in the range of $-100^{\circ}C$ to $90^{\circ}C$ using a thermal vacuum chamber to utilize the vibrator in aerospace industries. As the results, at room temperature, the resonant and anti-resonant frequencies had the minimum value, whereas, the dielectric constant increased linearly from about 2500 to 7500 in the given temperature range. The mechanical loss decreased linearly from 0.08 to 0.03. Through the regression analysis, the temperature dependence functions of the characteristics were derived to linear and square regression functions. Applying the functions, the input admittance characteristics of the piezoelectric vibrator were calculated, and the results showed good agreement with measured ones. It can be confirmed that this method is useful to estimate the characteristics change of the piezoelectric vibrator caused by the temperature change under the space environment.

• Composites Research
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• v.29 no.6
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• pp.395-400
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• 2016

Recently, many research groups have studied on the epoxy-based multifunctional electrolyte to develop the structural composite bearing high mechanical properties without sacrificing the ionic conductivity at the same time. The studies on the optimal content and material selection for structural electrolyte have been published, while its curing behavior has not much analyzed yet. In this study, epoxy-based structural electrolyte containing solid electrolyte was prepared by varying the curing temperature and time. In addition, the ionic conductivities and mechanical properties of specimens were measured. We also find out the optimal hardening condition where the epoxy domain enables to be hardened within the range of temperature at which the thermal decomposition of electrolyte does not occur. Finally, we propose the multifunctional structural electrolyte showing achievable electrical and mechanical properties (282 MPa and $9{\times}10^{-6}S/cm@25^{\circ}C$).

• Applied Chemistry for Engineering
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• v.21 no.6
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• pp.664-669
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• 2010

The forest area of domestic is 6370304 ha, which covers 70% of the whole country, and especially Gangwon-do is remarkably larger than other Province. A thick forest of the country has the most basic component among other natural environments as well as it has invaluable worth to human being such as scientific research and educational value. However due to the breakout of forest fire since 1990s, the loss of trees, destruction of natural environment and ecology, economic damage have been occurring and its scale also has become larger. The causes of becoming larger in scale are resulted from forest components which mainly consist of needle leaf trees, wide leaf trees, fallen leaves, herbaceous plants so that it has been a direct cause for forest fire. However, few research on combustion and pyrolysis characteristics has been done in domestic and abroad. The study on the combustion and pyrolysis for Pinus densiflora which are typical needle leaf trees has been tried using TGA. Pinus desiflora started to being ignited at around $162^{\circ}C$ and pyrolysis was done at around $197^{\circ}C$. Differential method was applied to calculate activation energy and frequency factor according to the variation of conversion. Activation energy in pyrolysis was increased from 79 kJ/mol to 487 kJ/mol with increasing conversion and average activation energy was 195 kJ/mol. The activation energy in combustion was decreased from 148 kJ/mol to 133 kJ/mol.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.3
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• pp.24-37
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• 2024

Due to the thin nature of semiconductor packages, even minor thermal loads can cause significant warpage, impacting product reliability through issues like delamination or cracking. The mold curing process, which encloses the package to protect the semiconductor chip, is particularly challenging to predict due to the complex thermal, chemical, and mechanical interactions. This study proposes a cost-effective machine learning model to predict warpage in the mold curing process. We developed methods to characterize the curing degree based on time and temperature and quantify the material's mechanical properties accordingly. A Finite Element Method (FEM) simulation model was created by integrating these properties into ABAQUS UMAT to predict warpage for various design factors. Additionally, a Warpage formula was developed to estimate local warpage based on the package's stacking structure. This formula combines bending theory with thermo-chemical-mechanical properties and was validated through FEM simulation results. The study presents a method to construct a machine learning model for warpage prediction using this formula and proposes a cost-effective approach for building a training dataset by analyzing input variables and design factors. This methodology achieves over 98% prediction accuracy and reduces simulation time by 96.5%.

• Applied Chemistry for Engineering
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• v.23 no.3
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• pp.271-278
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• 2012

In this work, we have prepared the nanocomposite by the reaction of mica and zinc oxide, and investigated the application of nanocomposite to UV protecting creams. Mica treated with 3-aminopropyltrimethoxysilane (APTMS) reacted with 1,4-phenylenediisothiocyanate (PDC) to give -N=C=S functionalized surface, which was further reacted with zinc oxides coated with APTMS to give mica-zinc oxide nanocomposites. The composites were characterized by EA, EDS, TGA, SEM, zeta potential measurement, powder XRD, and DRS UV/Vis analyses. Finally, we measured transmittances of ultraviolet protection creams manufactured by using mica composite covered with zinc oxides in the range of 280~400 nm. The nanocomposites developed in this work might be applicable as inorganic hybrid materials for UV protecting creams.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.108-108
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• 2011

공동주택에서 2025년 정부가 추진하고 있는 Zero Energy 건축물 구현과 친환경에 대한 탄소배출 저감 문제로 재생에너지 생산시스템의 추가 적용은 반드시 필요하다. 따라서 공동주택 적용 및 활용성을 높일 수 있는 BIPV시스템 개발을 통하여 설치면적 확보와 세대 활용성을 높일 수 있도록 하는 것이 필요하다. 특히 거실 창호의 경우 주방향이 남향, 남동 또는 남서향으로 배치되어 태양광을 적용하기에 적합한 특성을 가지고 있다. 그러나 창호는 건물외피의 역할과 재실자가 조망과 정보취득을 얻을 수 있는 중요한 통로가 되기 때문에 단열 문제나 시야 차폐의 문제는 발생하지는 않도록 하는 것이 필요하다. 본 연구에서는 a-si타입 모듈 2개를 10% 투과율로 Bsck Coating 색상을 달리한 모듈과 c-si BIPV 모듈을 커튼월 창호시스템으로 개발, 일반 2중 창호시스템과 비교 평가를 위해 실제 Test bed 건물에 시공하여 시환경 및 실내 창측면 온도변화 측정 분석을 진행하였다. 현재 국내외 출시되고 있는 a-si see through 모듈은 10~30%의 투과율로 창 마감재로 대체가 가능하나 건축 환경(시환경,열환경)에 대한 분석은 전무한 상태이다. 본 연구에서는 시환경과 창유리면의 열 부하, 자외선, 적외선 차폐 및 가시광선의 투과율에 대한 평가와 Back Coating에 따른 색온도 평가를 통해서 a-si BIPV의 공동주택 세대 발코니 창호 적합성에 대한 검토를 진행하였다. 연구결과는 아래와 같다. ${\bullet}$ 실내조도는 청천공 정오기준 가시성 확보 모듈의 경우 2,300 ~ 3,500lx를 나타내고 있어 대비 현상이나 창측의 급격한 조도 변화가 적은 시환경 구축이 가능 ${\bullet}$ 12시경 휘도는 창측면, 실내 벽체, 코너 바닥면을 대상으로 a-si BIPV 모듈을 적용한 경우 휘도비가 12:1로 KS나 IESNA의 광원과 근접면의 비 20:1 범위에 모두 존재, 적합한 것으로 분석되었으나 c-si의 경우는 그림자로 인한 대비 현상이 발생, 작업 시환경 문제 발생. ${\bullet}$ 이중시스템 창호와 비교하여 단열 성능 떨어짐. 발전시간대 창유리 면 온도 상승 으로 하절기 냉방부하 증가. ${\bullet}$ 자외선은 100% 가까이 차단, 적외선은 13~42%만 투과되고 가시광선은 13% 투과율을 나타내어 일반 창에 칼라 코팅을 적용하는 것과 유사한 경향을 나타냄.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.100-104
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• 2013

In this paper, we present an optimal threshold setting method for flame detection of infrared thermal image. Conventional infrared flame detection methods used fixed intensity threshold to segment candidate flame regions and further processing is performed to decide correct flame detection. So flame region segmentation step using the threshold is important processing for fire detection algorithm. The threshold should be change in input image depends on camera types and operation conditions. We have analyzed the conventional thresholds composed of fixed-intensity, average, standard deviation, maximum value. Finally, we extracted that the optimal threshold value is more than summation of average and standard deviation, and less than maximum value. it will be enhance flame detection rate than conventional fixed-threshold method.

• Journal of Marine Life Science
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• v.5 no.1
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• pp.17-24
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• 2020

We have identified a heat shock protein 70 gene from freshwater snail, Semisulcospira coreana. The freshwater snail HSP70 gene encode a polypeptide of 639 amino acids. Based on bioinformatic sequence characterization, HSP70 gene possessed three classical signature motifs and other conserved residues essential for their functionality. The phylogenetic analysis showed that S. coreana HSP70 had closet relationship with that of golden apple snails, Pomacea canaliculata. The HSP70 mRNA level was significantly up-regulated in response to thermal and salinity challenges. These results are in agreement with the results of other species, indicating that S. coreana HSP70 used be a potential molecular marker in response to external stressors and the regulatory process related to the HSP70 transcriptional response can be highly conserved among species.