• 대한수학회논문집
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• 제18권3호
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• pp.533-540
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• 2003

We introduce the notion of semi-convergence of p-stacks and by using that notion we characterize the semi-interior, semiclosure, separation axioms and semi-continuity on a topological space. Also we introduce a new notion of p-somicompactness and investigate its properties in terms of semi-convergence of p-stacks.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제14권1호
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• pp.15-21
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• 2007

We introduce the notion of pre-convergence of p-stacks and characterize the pre-interior, pre-closure, separation axioms and pre-continuity on a topological space by using pre-convergence of p-stacks. We also introduce the notion of p-precompactness and investigate its properties in terms of pre-convergence of p-stacks.

• 대한수학회논문집
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• 제21권4호
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• pp.749-758
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• 2006

In [1], we introduced the notion of p-stacks. In this paper, by using p-stacks we characterize $S^*-continuous$ functions, separation axioms, supracompactness and some properties on supratopological spaces. We also introduce the notion of p-supracompactness and study some properties.

• 한국산업보건학회지
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• 제10권1호
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• pp.18-31
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• 2000

A stack must be designed to 1) reduce or eliminate rainfall or snowfall into a industrial exhaust system, 2) minimize a resistance to flow, 3) maximize the vertical dispersion of the contaminated air and 4) minimize maintenance. The weather cone stacks and the elbow-type stacks are very popular in Korea. But they add some resistance to the exhaust system resulting in reduction of air flow rate, but also deflect the noxious contaminants downward in undiluted form. To solve these problems, ACGIH (American Conference of Governmental Industrial Hygienists) suggested the vertical discharge stack with concentric space between the upper stack with larger diameter and the lower stack with smaller diameter. The preliminary test showed that the vertical discharge stacks did not have the good rainfall protection. The reversed cone were newly devised to satisfy the requirements for the good stack. Subsequently, the amount of rain being penetrated through the stacks was measured while the stacks were simultaneously and naturally exposed to rain in the same area outside. Test results indicate that none of the stacks tested completely exclude rain. The efficiency of rainfall protection and the pressure loss coefficient were compared. The temporary conclusion was reached to the point that the reversed cone stack is the best one. Further research is underway.

• 한국세라믹학회지
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• 제51권3호
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• pp.197-200
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• 2014

We investigated the influence of blistering on $Al_2O_3$/SiON stacks and $Al_2O_3$/SiNx:H stacks passivation layers. $Al_2O_3$ film provides outstanding Si surface passivation quality. $Al_2O_3$ film as the rear passivation layer of a p-type Si solar cell is usually stacked with a capping layer, such as $SiO_2$, SiNx, and SiON films. These capping layers protect the thin $Al_2O_3$ layer from an Al electrode during the annealing process. We compared $Al_2O_3$/SiON stacks and $Al_2O_3$/SiNx:H stacks through surface morphology and minority carrier lifetime after annealing processes at $450^{\circ}C$ and $850^{\circ}C$. As a result, the $Al_2O_3$/SiON stacks were observed to produce less blister phenomenon than $Al_2O_3$/SiNx:H stacks. This can be explained by the differences in the H species content. In the process of depositing SiNx film, the rich H species in $NH_3$ source are diffused to the $Al_2O_3$ film. On the other hand, less hydrogen diffusion occurs in SiON film as it contains less H species than SiNx film. This blister phenomenon leads to an increase insurface defect density. Consequently, the $Al_2O_3$/SiON stacks had a higher minority carrier lifetime than the $Al_2O_3$/SiNx:H stacks.

• 대한수학회지
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• 제44권1호
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• pp.189-198
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• 2007

We have defined a bijective map from certain set of coinstacks onto the permutations avoiding 132-pattern and give an algorithm that finds a corresponding permutation from a given coin-stack. We also list several open problems which are similar as a CS-partition problem.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.128-132
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• 2003

This paper deals with the development of IGBT stacks for cost reduction. One stack is consist of 4 IGBTS in parallel. In the high- and mid-power converters, IGBT stacks are more suitable than single IGBTS in the aspects of total cost of semiconductor devices, time for purchasing, maintenance, radiation of heat, size of surge absorber and harmonic filter, frequency characteristics, and etc.. Problems accompanied by parallel construction are studied and solved. Economical efficiency is discussed and field tests with 100kVA UPS are tarried out to verify the validity of the developed IGBT stacks.

• 한국문헌정보학회지
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• 제49권3호
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• pp.437-456
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• 2015

본 연구의 목적은 선행연구에서 밝혀진 자동서고의 자료 수장 효율을 다른 유형의 서고와 비교 분석하는데 있다. 국내외의 대학도서관은 장서 증가에 따라 자료 수장 효율을 높이기 위한 방안으로 자동서고시스템을 도입하였다. 선행연구에 의하면 자동서고는 개가제 서고나 고정서가형 및 이동서가형 보존서고보다 자료 수장 효율이 높다. 본 연구는 우리나라 S대학교도서관 자동서고의 자료 수장량을 개가제 서고와 가상의 고정서가 형 및 이동서가형 보존서고의 수장량과 비교하였다. 조사결과 자동서고는 개가제 서고보다 최대 6배, 고정서가형 보존서고보다 최대 3.61배 그리고 이동서가형 보존서고보다 최대 1.45배 높은 것으로 나타나, 선행연구에서 밝혀진 것보다는 자료 수장 효율이 낮았다.

• 한국전기전자재료학회논문지
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• 제36권3호
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• pp.226-232
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• 2023

As a potential alternative to flash memory, HfO₂/Al₂O₃ stacks appear to be a viable option as charge capture layers in charge trapping memories. The paper undertakes a review of HfO₂/Al₂O₃ stacks as charge trapping layers, with a focus on comparing the number, thickness, and post-deposition heat treatment and γ-ray and white x-ray treatment of such stacks. Compared to a single HfO₂ layer, the memory window of the 5-layered stack increased by 152.4% after O₂ annealing at ±12 V. The memory window enlarged with the increase in number of layers in the stack and the increase in the Al/Hf content in the stack. Furthermore, our comparison of the treatment of HfO₂/Al₂O₃ stacks with varying annealing temperatures revealed that an increased annealing temperature resulted in a wider storage window. The samples treated with O₂ and subjected to various γ radiation intensities displayed superior resistance. and the memory window increased to 12.6 V at ±16 V for 100 kGy radiation intensity compared to the untreated samples. It has also been established that increasing doses of white x-rays induced a greater number of deep defects. The optimization of stacking layers along with post-deposition treatment condition can play significant role in extending the memory window.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.121-124
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• 2007

Stacks of solid oxide fuel cell under 1kW max power were designed on planar type employing anode supported cell and metallic interconnects. The stacks composed of 3-cells, 8-cells, and 16-cells were fabricated by using single cell purchased from Indec, sealant and interconnect prepared at RIST. In performance test of the final 16-cells stacks, OCV was recorded to be 16.7 V. Peak power and power density were 1 kW, 0.77 $W/cm^{2}$ at $820^{\circ}C$, respectively. In addition, the long term degradation rate of the power exhibited 2.25 % in 500 h at $750^{\circ}C$.