• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.207-210
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• 2005

The results of combustion performance test of fuel-rich gas generator with dual swirl injectors are described. By changing simulating duct and recess number(RN) of the injectors, we inspected whether the combustion instability took place. When the injectors of RN = 0.5 were used, combustion instabilities could be reduced using the simulating duct. However, the effect of the simulating duct on the gas generator with the injectors of RN = 1.5 was not significant.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.2
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• pp.65-73
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• 1979

Experiment was conducted to study the optimum sowing date and nursery duration at Jean An from 1976 to 1978 and their influence on the growth, dry matter production during growth period of the rice plant. In case of Tongil lines, the lengthening of nursery duration and late sowing increased unexpected heading and prolonged heading and maturing period. High yield were obtained by increasing dry matter accumulation during growth period of rice plant. To obtain safe yield in Tongil lines transplanting must be done before May 30th.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.503-503
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• 2007

본 논문에서는 지중배전(22.9kV) 선로에 사용되는 지상변압기를 대상으로 수행한 방열해석 및 개선과 변압기수명연장에 관한 검토 결과를 수록하였다. 변압기의 열화메커니즘에 대한 문헌 조사를 통해 변압기 온도와 수명간의 관계를 작도하였는바, 수명 평가를 위한 핵심 인자로 열에 의한 절연지의 열화에 초점을 맞추었다. 기존 외함에 설치된 방열구중 상부 위치를 상부판에도 변경하는 경우 약25%의 통풍량 증가 효과를 기대할 수 있을 것으로 평가 되었으며 상부판과 내함 사이에 형성되던 고온 영역에서의 온도를 약$15^{\circ}C$정도 낮출 수 있는 것으로 나타났다. 절연지의 인장강도 변화로 평가한 수명예측 곡선에 따르면 약$10^{\circ}C$의 은도 저감은 약10배의 수명 연장 효과를 가져오는 것으로 나타난바, 본 연구에서 확인한 방열구의 위치 변경에 따른 지상기기 내부의 온도 저하는 변압기 수명을 연장하는데 일조할 것으로 기대된다. 기존 지상변압기에서의 방열구조를 통해 변압기 온도와 수명간의 관계를 작도하였는바, 수명 평가를 위한 핵심인자로 효과적으로 방열할 수 있는 새로운 외함의 구조 및 디자인을 제시하고 시뮬레이션을 통해 개선효과를 예측하였다. 또한, 개선된 모델을 가지고 실제 변압기를 제작한 후 부하를 인가하여 개선전과 후에 대한 방열효과를 실증시험을 통해 확인하였다.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.236-236
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• 1994

Acetylsalicylic acid (ASA)와 고려홍삼의 항산화 성분인 maltol을 축합하여 신물질 aspalatone을 합성하고, 흰쥐에서의 지혈시간 연장 효과, 항혈소판 응집 억제 (in Vitro, ex ViVO) 효과 및 생쥐의 혈전 모델을 이용한 항혈전 (in vivo) 효과를 연구하였다. SD계 웅성 흰쥐에 15 mg/kg의 낮은 용량으로 경구투여 할 경우, aspalatone과 ASA는 각각 최소한 8일 연속투여후 지혈시간을 유의적으로 연장시켰으며 같은 용량으로 10일 간 경구투여. 하였을 때, aspalatone 투여군은 대조군에 비하여 지혈시간이 57% (p<0.005) 연장된 반면, ASA 투여군은 44% 연장되었다. 반면, aspalatone의 아세칠 기를 갖지 않는 salicylic acid maltnl ester는 같은 용량에서 지혈시간을 유의적으로 연장시키지 않았다. Aspalatone은 in vitro에서 collagen에 의해 유도된 흰쥐 혈소판 응집을 강력하게 억제하였으나 (IS$_{50}$ = 0.18 mM), ASA와 마찬가지로 ADP에 의한 응집은 억제하지 않았다. Aspalatnne과 다른 대조약물들의 ex vivo에서의 혈소판 응집 억제능은 ASA>dipyridamdle(equation omitted)aspalatone>ticlopidine의 순이었다. 1회 경구투여로 aspalatone은 생쥐의 collagen에 의한 혈전에 기인하는 치사율을 억제하였다 (ED$_{50}$ = 32mg/kg). Aspalatone을 10일 간 투여하면 유효용량이 현저히 감소하여 20 mg/kg에서 치사율을 90% (p<0.001) 억제하였으며, 이러한 항혈전 효과는 투여중단 4일 후에도 지속되었다. 또한, 경구투여시 위궤양을 유발하는 ASA (ulcer index : 29 mm 200 mg/kg p.o.)와는 다르게 aspalatone은 위궤양을 유발하지 않는다는 장점을 갖는다 (0.71 mm, 800 mg/kg p.o.). In vitro에서 malondialdehyde 생성 억제를 지표로 한 aspalatone의 항산화 활성 ($IC_{50}$/ = 0.11 mM)은 maltol ($IC_{50}$/ = 0.084 mM)과 유산하다. 이러한 실험결과를 토대로 하여 aspalatone을 위궤양을 유발하지 않는 항혈전 신약으로 개발하기 위한 연구가 진행 중이다.

• The Journal of Engineering Geology
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• v.20 no.2
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• pp.155-167
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• 2010

In analysis of slope stability, deterministic analysis which yields a factor of safety has been used until recently. However, probability of failure is considered as a more efficient method because it deals with the uncertainty and variability of rock mass. In both methods, a factor of safety or a probability of failure is calculated for a slope although characteristics of rock mass, such as characteristics of joints, weathering degree of rock and so on, are not uniform throughout the slope. In this paper, we divided a model slope into several zones depending on conditions of rock mass and joints, and probabilities of failure in each zone are calculated and compared with that calculated in whole slope. The persistence of joint was also used as a parameter in calculation of probability of failure. A rock slope located in Hongcheon, Gangwondo was selected and the probability of failure using zoning and persistence as parameter was calculated to confirm the applicability of model analysis.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.2
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• pp.134-140
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• 2018

Clinical crown lengthening procedure would be an effective method for overcoming adverse clinical condition such as short abutment length. There are three kinds of methods in clinical crown lengthening, those are, surgical crown lengthening, orthodontic extrusion and surgical extrusion. Clinicians have to try their best to choose a proper method among those for favorable results. This report aims to review the considerations in each method with various cases and to suggest a decision flow for appropriate selection.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.5
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• pp.335-343
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• 2009

The crossed cube has received great attention because it has equal or superior properties compared to the hypercube that is widely known as a versatile parallel processing system. It has been known that disjoint two copies of a mesh of size $4{\times}2^m$ or disjoint four copies of a mesh of size $8{\times}2^m$ can be embedded into a crossed cube with dilation 1 and expansion 1 [Dong, Yang, Zhao, and Tang, 2008]. However, it is not known that disjoint multiple copies of a mesh with more than eight rows and columns can be embedded into a crossed cube with dilation 1 and expansion 1. In this paper, we show that disjoint $2^{n-1}$ copies of a mesh of size $2^n{\times}2^m$ can be embedded into a crossed cube with dilation 1 and expansion 1 where $n{\geq}1$ and $m{\geq}3$. Our result is optimal in terms of dilation and expansion that are important measures of graph embedding. In addition, our result is practically usable in allocating multiple jobs of mesh structure on a parallel computer of crossed cube structure.

• Polymer(Korea)
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• v.35 no.2
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• pp.171-175
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• 2011

Isophorone diisocyanate(IPDI), polytetramethylene glycol 1000 (PTMG1000), and N-methyl diethanol amine (MDEA) were applied to prepare cationic polyurethane water dispersions (PUD). Various neutralizers and chain extenders were introduced in order to investigate property changes, such as particle size, viscosity, $T_g$, tensile strength, and water swellability, depending on chemical structure of those chemicals. While the PUDs neutralized by acetic acid showed a typical elastomeric behavior, the others used with hydrochloride presented crystalline behavior. Among chain extenders isophorone diamine (IPDA) provided the best mechanical property. The particle size of the PUD neutralized with HCl was smaller than that with acetic acid. It is believed that this is attributed to the size difference of counter ions. The PUD chain-extended with hydrazine had the smallest particle size.

• The KIPS Transactions:PartA
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• v.14A no.6
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• pp.327-332
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• 2007

In this paper, we will analysis embedding between $2^{2n-k}{\times}2^k$ torus and interconnection networks HFN(n,n), HCN(n,n). First, we will prove that $2^{2n-k}{\times}2^k$ torus can be embedded into HFN(n,n) with dilation 3, congestion 4 and the average dilation is less than 2. And we will show that $2^{2n-k}{\times}2^k$ torus can be embedded into HCN(n,n) with dilation 3 and the average dilation is less than 2. Also, we will prove that interconnection networks HFN(n,n) and HCN(n,n) can be embedded into $2^{2n-k}{\times}2^k$ torus with dilation O(n). These results mean so many developed algorithms in torus can be used efficiently in HFN(n,n) and HCN(n,n).

• Journal of the Institute of Convergence Signal Processing
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• v.24 no.4
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• pp.229-235
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• 2023

Recently, for drones to be used for agricultural applications, it is necessary to increase the payload and extending flight time. Currently, the payload and extending flight time are limited by the battery technology for solar paper drone. In addition, charging or replacing the batteries may be a practical solution at the field that requires near continuous operation. In this paper, the procedure to optimize the main power system of an electric hybrid drone that consists of a battery and electric motor is presented. As a result, the solar paper drone flied successfully for 2-3%. The developed solar paper drone consumes and average of 55W when cruising and can receive up to 25W of energy during the day, and its extending flight time was verified through flight tests.