• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.478.2-478.2
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• 2014

Atomic layer deposition (ALD) provides self-limiting processes based on chemisorption-based reactions. Such unique features allow for superior step coverage, atomic-scale control in thickness, and surface-dependent reaction controls. Furthermore, the surface-limited deposition enables the artificial deposition of oxide and/or metallic materials onto the porous systems as long as the supply is guaranteed in terms of time in providing reactant species and removing the byproducts and redundant reactants. The unique feature of atomic layer deposition is applied to solid oxide fuel cells whose incorporates two porous cathode and anode compartments in addition to the ionic electrolyte. Specific materials are deposited to the surface sites of porous electrodes, with the aim to controlling the triple phase boundaries crucial for the optimized SOFC performances. The effect of ALD on the SOFC performance is characterized using current-voltage characteristics in addition to frequency-dependent impedance spectroscopy. The pros and cons of ALD-controlled SOFCs are discussed toward high-performance SOFC systems.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.2
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• pp.127-135
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• 2009

Reid and Kajiura(1957) has studied on the wave damping rate over a permeable bed of infinite depth. In this study, wave damping rate over a permeable bed of finite depth is derived by linear wave theory. It is then extended to derive wave damping rates over a double or triple layer, each of which consist of different material. Applying the wave damping rate to the mild slope equation, the wave transmission coefficient over a permeable bed has been calculated. The model has been certificated by comparing with the result of Flaten and Rygg(1991)'s integral equation method in the case of a single-layer bed.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.417-417
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• 2016

Global environmental deterioration has become more serious year by year and thus scientific interests in the renewable energy as environmental technology and replacement of fossil fuels have grown exponentially. Photoelectrochemical (PEC) cell consisting of semiconductor photoelectrodes that can harvest light and use this energy directly to split water, also known as photoelectrolysis or solar water splitting, is a promising renewable energy technology to produce hydrogen for uses in the future hydrogen economy. A major advantage of PEC systems is that they involve relatively simple processes steps as compared to many other H2 production systems. Until now, a number of materials including TiO2, WO3, Fe2O3, and BiVO4 were exploited as the photoelectrode. However, the PEC performance of these single absorber materials is limited due to their large charge recombinations in bulk, interface and surface, leading low charge separation/transport efficiencies. Recently, coupling of two materials, e.g., BiVO4/WO3, Fe2O3/WO3 and CuWO4/WO3, to form a type II heterojunction has been demonstrated to be a viable means to improve the PEC performance by enhancing the charge separation and transport efficiencies. In this study, we have prepared a triple-layer heterojunction BiVO4/WO3/SnO2 photoelectrode that shows a comparable PEC performance with previously reported best-performing nanostructured BiVO4/WO3 heterojunction photoelectrode via a facile solution method. Interestingly, we found that the incorporation of SnO2 nanoparticles layer in between WO3 and FTO largely promotes electron transport and thus minimizes interfacial recombination. The impact of the SnO2 interfacial layer was investigated in detail by TEM, hall measurement and electrochemical impedance spectroscopy (EIS) techniques. In addition, our planar-structured triple-layer photoelectrode shows a relatively high transmittance due to its low thickness (~300 nm), which benefits to couple with a solar cell to form a tandem PEC device. The overall PEC performance, especially the photocurrent onset potential (Vonset), were further improved by a reactive-ion etching (RIE) surface etching and electrocatalyst (CoOx) deposition.

• Korean journal of applied entomology
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• v.45 no.3 s.144
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• pp.363-369
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• 2006

Effects of three packing materials and exposure time on the mortality of Plodia interpunctella and Tribolium castaneum were studied using $CO_{2}-modified$ atmosphere control. Materials used were triple layered craft paper (KKK), triple layered craft paper with one laminate coating layer (KLK), and triple layered craft paper with one HD film coating layer (KHK). In the test balls (${\phi}1.2\;m$) containing 85% $CO_{2}-modified$ atmosphere, concentration of $CO_{2}$ in small packing envelopes ($9.8{\times}9.8cm$) made of the materials after one day was higher in KKK ($26.67{\pm}0.58%$) than KLK ($23.33{\pm}0.58%$) or KHK ($20.67{\pm}0.58%$). Both P. interpunctella and T. castaneum showed higher mortality in KKK than in either KLK or KHK Similar results were obtained by larger space ($9{\times}4{\times}3m$) and packing volume (20 kg) studies. The effect of the packing materials was clearer on T. castaneum more tolerant to $CO_{2}$ than P. interpunctella. Regression of the insect mortality on cumulative concentration time (${\int}_{0}^{t}c{\times}tdc{\approx}{\sum}concentration{\times}time$) was highly significant. Control of P. interpunctella and T. castaneum by $CO_{2}-modified$ atmosphere were discussed in relation to packing materials, cumulative concentration time of $CO_{2}$ and food products.

• The Korean Journal of Malacology
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• v.31 no.2
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• pp.83-92
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• 2015

The effect of different intermediated rearing method by expanding the attached floor space in order to highly density culture on the growth characteristics and survival rate of the juvenile abalone, Haliotis discus hannai, were investigated in land-based tanks. The intermediated culture methods was determined thru the shelter counts and layer for 10 month with two replicates : the single layer shelter (SLS), the double layer shelter (DLS), the triple layer shelter (TLS) and the single layer shelter under net cage (SLSNC). In addition, the culture on shallow race way tank had to set up as culture of the ditch raceway tank (CDRT) and the floor race way tank (CFRT). In the growth performance of reared abalone (initial mean shell length $54.18{\pm}7.39mm$ and weight $1.93{\pm}0.14g$) at experimental tanks, that the absolute growth rate (ARG), daily growth rate (DGR) and specific growth rate (SGR) to the shell length and shell breadth was not significant at each experimental tanks except SLSNC. As well as too, weight gain (WG), daily weight gain (DWG) and specific weight gain (SWG) to weight was not significant at each experimental tanks except SLSNC, too. Survival rates of CDRT and CFRT was lower than those of different experimental tanks (P < 0.05). Therefore, these results is showed that high density different intermediated rearing method by expanding the attached floor space for juvenile H. discus hannai was not have difference as growth performance and survival rate both one layer shelter and multi layer shelter. Also, it is considered that shallow race way tank was not useful rearing for the juvenile intermediate culture of H. discus hannai in land based.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.133-133
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• 2010

3-5족 화합물 반도체를 이용한 집광형 삼중 접합 태양전지는 35% 이상의 광변환 효율로 주목을 받고 있다. 일반적으로 삼중 접합 태양전지는 넓은 영역대의 파장을 흡수하기 위해 밴드갭이 다른 InGaP, GaAs, Ge이 사용된다. 그 중 하부셀은 기계적 강도가 높고 장파장을 흡수할 수 있는 Ge이 사용되는데, p-type Ge 기판위에 III-V 결정막 성장 시 5족 원소가 확산되어 pn접합을 형성하게 된다. 이러한 구조를 가진 Ge 하부셀이 효율적으로 홀-전자 쌍을 형성하기 위해서는 두꺼운 베이스와 얇은 에미터 접합이 필요하다. InGaP의 phosphorus는 낮은 확산계수로 인해 GaAs의 arsenic에 비해 얇은 접합이 형성 가능하며, Ge표면 에칭효과가 더 적다는 장점이 있다. 이를 고려해 우리 연구그룹에서는 metalorganic chemical vapor depostion(MOCVD)을 이용하여 Ge기판위에 성장한 InGaP layer의 특성을 관찰해 보았다. <111>로 $6^{\circ}$ 기울어진 p-type Ge(100) 기판위에 MOCVD를 통해 InGaP layer를 형성하였고, 성장된 layer를 atomic force microscope(AFM)와 high-resolution x-ray diffraction(HRXRD)을 이용하여 표면형상, 조성, 응력상태 등을 각각 관찰하였다. 또한 phosphorus 확산에 의해 형성되는 도핑농도는 electrochemical capacitance-voltage(ECV)을 이용하여 관찰하였다. 성장된 Ge기판위의 InGaP layer의 경우 특징적으로 높이 50 nm, 밑변 길이 $1\;{\mu}m$의 경사진 표면을 관찰할 수 있었으며, 이러한 구조는 TMIn과 TMGa의 비율이 증가 할수록 감소하였다. 따라서 이러한 경사진 형태의 구조는 격자 불일치 때문인 것으로 판단된다. 추가적으로 V/III ratio의 최적화를 통해 1.3 nm의 표면 거칠기를 갖는 InGaP layer를 얻을 수 있었다. ECV를 통해 Ge 하부셀의 pn접합 형성을 관찰한 결과 약 160 nm에서 접합이 형성되는 것을 관찰할 수 있었다. 또한, 같은 성장 조건의 샘플을 1000 초 열처리 후에 접합깊이의 변화를 관찰한 결과 180 nm에서 접합이 관찰되었지만, GaAs의 arsenic에 의한 pn접합은 열처리 후에 그 깊이가 170 nm에서 300 nm로 증가 하였다. 따라서 삼중접합 태양전지의 제작 공정을 고려할 경우 phosphorus에 의한 접합 형성이 Ge 하부셀의 동작 특성에 유리할 것으로 판단된다.

• The Korean Journal of Zoology
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• v.3 no.2
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• pp.1-4
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• 1960

Urticating spicules and poison -secreting cells of the last instar larva in Euproctis flava BREMER was studied histologically. Three kinds of cells in the epidermis of tubercles on the lst to 8th abodominal segments are classified according to the arrangement of their nuclei : smallepidermal cells, large gland cells, and elongated trichogen cells. As a result of Mallory's triple straining , the epicuticle , the papila-like structure apart form the tubules inside which are gathered at the base and connected with a middle layer cell through a canal in the cuticle, and the peripheral of the urticating spcicule are yellow. However, the inside of the spicule , the tubules within the papilla-like structure, the canal in the cuticle , nuclei in the pidermal cells and the thin exocuticle are red although the thich endocuticle is blue. Particularly , the large nuclei in the middle layer cells are bright red, the cytoplasms of which are little and stained red, too, and the inside of the spicules apt to be stained red when they are broken. The contents therefore seem to be continuous between the spicules and the large cells. Presumably , the large cell at the middle layer is not te tormogen cell which Tsutsumi (1958) has described , but the gland cell which secretes the poison-substance into spicules as Pawlowsky and Stein 91927) and Tonkes (1933) pointed out. Whether the pisonous substance is secreted from the gland cell into the cytoplasmic processes of the trichogen cells which stick large middle layer cells during the formation of the new spicule as Tsutsumi (1958) has observed, or the gland cell makes a new connection with the spicule after the spicule is formed is not clear.

• Journal of the Korean Magnetics Society
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• v.21 no.4
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• pp.132-135
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• 2011

The exchange bias field ($H_{EX}$) and the coercivity ($H_C$) variation and change depending on the thickness of intermediately super-soft magnetic NiFeCuMo layer with different thickness of the bottom NiFe layer were investigated. The $H_{EX}$ of triple pinned NiFe(4 nm)/NiFeCuMo($t_{NiFeCuMo}$= 1 nm)/NiFe(4 nm)/FeMn multilayer has the maximum value more less than one of single pinned NiFe(8 nm)/FeMn layer. If NiFeCuMo layer is inserted each into between the pinned and free NiFe layers, we can be used as GMR-SV device for a bio-sensor that has improved magnetic sensitivity.

• The Korean Journal of Ceramics
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• v.6 no.2
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• pp.177-182
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• 2000

At the porous $La_{0.6}Ca_{0.4}MnO_{3-{\delta}}$(LCM)/YSZ electrodes of solid oxide fuel cells (SOFC), the electrochemical redox reaction of oxygen proceeds via the triple boundary (TPB) of gas/LCM/YSZ. The surface diffusion of adsorbed oxygen on LCM has been proposed as the rate determining process, assuming the gradient of oxygen chemical potential from the outer surface of porous layer to TPB. Along with the formation of this gradient, oxygen nonstoichiometry in the bulk of LCM may varies. In this paper, an electrochemical technique was described precisely to determine the variation of oxygen content in LCM of porous LCM/YSZ under polarization. It was shown that the oxygen potential in LCM layer under large cathodic polarization is much lower than that in the gas phase, being determined from the electrode potential and Nernst equation.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.295-298
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• 2009

Oxygen ionic conductors of CeScSZ electrolyte in SOFC unit cell are applied to anode and cathode as well as electrolyte to have the triple-phase-boundaries of electrochemical reaction, and it is required to decrease the sintering temperature of anode-supported electrolyte by the nanoscale of CeScSZ electrolyte powder. In this report, nanoscale CeScSZ electrolyte powder was synthesized by chemical synthesis method. The particle size, surface area and morphology of the powder were observed by SEM and BET. Thin film electrolyte of under $10{\mu}m$ was fabricated by tape casting using the synthesized CeScSZ electrolyte powder, and ionic conductivity and gas permeability of electrolyte film were evaluated. Finally the SOFC unit cell was fabricated using the anode-supported electrolyte prepared by a tape casting method and co-sintering, in which the active layer, measuring $20{\mu}m$, was introduced in the anode layer to provide a more efficient reaction. Electrochemical evaluations of the SOFC unit cell, including measurements such as power density and impedance, were performed and analyzed.