• Journal of the Korean Geotechnical Society
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• v.29 no.3
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• pp.61-70
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• 2013

Evaluation of permeability and coefficient of consolidation of clayey sand is critical in analyzing ground stability or environmental problems such as prediction of pollutant transport in groundwater. In this study, permeability tests using a flexible wall permeameter are performed to derive the coefficient of consolidation and permeability of reconstituted soil samples with various mixing ratios of kaolin clays and two different types of sands, which are Jumunjin and Ottawa sands. The test results indicate that the coefficient of consolidation and permeability plots linearly against clay contents in semi-log scale graphs for low clay mixing ratios ranging between 10 to 30%. It is also demonstrated that coefficient of consolidation and permeability of sand and clay mixture are dependent on the soil structure. Contrary to previous findings, the permeability is shown to be independent of the void ratio at low mixing ratios, which can be classified as non-floating fabric. The permeability decreases with the void ratio for floating fabric.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.74-74
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• 2009

카본나노튜브(CNT) 복합체는 우수한 기계적 성질을 가지고 있어 다양한 분야에서 연구되고 있다. 본 연구에서는 카본나노튜브(CNT)를 간단한 볼밀공정을 사용하여 Sn3.5Ag solder ball과 SAC305 powder 표면에 혼합하고 이를 통해 접합부 특성을 관찰하였다. 볼밀을 실시하기 전 카본나노튜브(CNT)는 초음파을 이용하여 분산을 실시하였다. Sn3.5Ag solder ball의 직경은 450um이고 SAC305 powder의 직경은 약 30um이었으며 이때 사용한 볼밀볼의 직경은 각각 3mm, 1mm이다. 볼밀 회전속도는 약 300rpm이고 6, 12, 18, 24시간동안 볼밀을 실시하였다. 24시간 볼밀 후에도 solder ball과 solder powder의 모양은 크게 변하지 않았다. SEM을 통해 표면을 관찰한 결과 분산된 카본나노튜브(CNT)는 solder ball과 solder powder의 표면에서 관찰되었다. 카본나노튜브(CNT)가 삽입된 solder ball은 BGA coupon 위에 놓고 Reflow를 실시하여 접합하였고 solder powder은 flux를 첨가하여 paste로 제조하여 2012 chip에 대한 접합특성을 관찰하였다. 카본나노튜브(CNT)는 solder ball 내부의 표면근처에서 관찰되었으며 카본나노튜브(CNT)가 혼합된 solder ball은 Aging 실시 후에 IMC 두께가 카본나노튜브(CNT)가 혼합되지 않은 solder ball에 비해 두께가 작고 접합강도는 약 10% 증가하였다. 또한 카본나노튜브(CNT)가 혼합된 solder paste와 카본나노튜브(CNT)가 혼합되지 않은 solder paste를 비교한 결과 인쇄성은 모두 양호하였으며 카본나노튜브(CNT)가 혼합된 paste를 사용한 chip의 전단강도가 높게 나타났다.

• Resources Recycling
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• v.12 no.6
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• pp.47-56
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• 2003

PVC(polyvinyl chloride) powder were mixed with EAF(Electric Arc Furnace) dust and made as pellets. In order to recover the hydrochloride emitted from pyrolysis of PVC and the valuable metals in dust through making chlorides, pellets were roasted at $300 ^{\circ}C$ and investigated about the generation of chlorides. Two dust samples were collected at I steel making Co. and P Co. (called I dust and P dust respectively), which were mainly composed of zincite and franklinite. It was confirmed that about 50% of Zn in I dust and 48% of Zn in P dust compose zincite. The emission of HCl gas was completed in 15 min at 30$0^{\circ}C$ and the HCl mostly reacted with dust and made chlorides under 20% PVC mixed ratio. Because the reaction of HCl with zincite was faster than with franklinit, when generation and volatilization of ferric chloride is not allowed, the equivalent PVC powder mixed ratio in pellet depended on the amount of zincite in dust.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.10
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• pp.1531-1535
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• 2005

The present study was designed to investigate the antidiabetic effect of Cordyceps militaris on activities of hepatic glucose-regulating enzymes, such as glucokinase (GK), pyruvate dehydrogenase (PDH) and acetyI-CoA carboxylase (ACC). We have isolated the active compounds, CM-A and CM-B from C. militaris and the extracts are under investigation to determine their mechanism of action. Hepatic GK, PDH and ACC activities were significantly (p < 0.05) increased compared with the control. Treatment with CM-A led to a rise in percentage of enzymes by 380$\%$,396$\%$ and 286$\%$, respectively, relative to control levels. CM-B were 329$\%$, 312$\%$ and 239$\%$, respectively. The increase in GK and ACC activities was linearly proportional with increased ratio of CM-A. Our findings suggest that C. militaris exerted antihyperglycemic potency, which is thought to be mediated through activation of GK, PDH and ACC enzymes related to glucose metabolism directly or indirectly and therefore C. militaris is promising as antidiabetic functional foods.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.5
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• pp.365-372
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• 2021

This paper deals with an optimal Weapon-Target Assignment (WTA) algorithm for Closed-In Weapon Systems (CIWS), considering variable burst time. In this study, the WTA problem for CIWS is formulated based on Mixed Integer Linear Programming (MILP). Unlike the previous study assuming that the burst time is fixed regardless of the engagement range, the proposed method utilizes the variable burst time based on the kill probability according to the engagement range. Thus, the proposed method can reflect a more realistic engagement situation and reduce the reaction time of CIWS against targets, compared to the existing method. In this paper, we first reformulate the existing MILP-based WTA problem to accommodate the variable burst Time. The proposed method is then validated through numerical simulations with the help of a commercial optimization tool.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.242-247
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• 2002

가. 느타리버섯 폐면 버섯퇴비를 종균과 혼합 입상하는 폐면입상기의 주요부위는 진동식 변량공급장치, 버킷엘리베이터 승강기, 승강식 수평 벨트콘베이어 수평이송장치로 구성되며, 통로가 좁은 생육분리형 재배사와 재래식 재배사에도 적응할 수 있도록 제작되었다. 나. 폐면 공급장치의 폐면 공급성능은 캠행정이 13mm로부터 16mm, 19mm로 커 질수록, 캠축의 회전수가 300rpm에서 700rpm으로 증가할수록 폐면의 공급성능은 높아지는 경향이었다. 다. 폐면 공급장치의 공급성능과 기체진동, 폐면 부착수준 등의 작업상태를 고려할 때 캠행정 16mm 회전수 550rpm 내외가 적당한 것으로 판단된다. 라. 시작기의 작업능률은 표준규격 200m$^3$인 버섯재배사 1동 1회당 14시간으로 관행(인력)작업의 50시간에 비해 3.5배 능률적이었다. 마. 버섯입상, 종균접종 작업경비는 1동 1회당 관행(인력)작업이 320,800원/200m$^3$.동에 비해 시작기는 130,300원/200m$^3$.동으로서 59,7%의 작업경비를 절감할 수 있는 것으로 분석되었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.259-259
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• 2021

하상을 구성하는 사립자들이 흐름에 의해 움직이기 시작하는 상태를 한계운동이라 하며, 한계운동이 시작될 때의 흐름조건을 한계조건이라 한다. 흐름에 부유되어 이동하는 부유사의 농도분포를 정확하게 산정하기 위해서는 하상재료의 침식율을 정확하게 산정하는 것이 필요하다. 특히 하상재료에 다양한 크기의 하상재료가 혼합되어 있을 때에는 차폐효과(Hiding-Exposure Effect)에 대한 고려가 필요하다. 여기서 차폐효과란, 동일한 크기의 사립자들로 구성된 균질 하상에 비해 비균질 하상에서 굵은 사립자가 흐름에 더 많이 노출되어 한계소류력이 감소하고, 잔 사립자의 한계소류력이 굵은 사립자로 인해 증가하는 현상을 의미한다. 하상토의 차폐효과는 Shields (1936)에서 제안된 무차원 한계소류력을 각 사립자의 크기별로 산정 한 후 보정계수를 곱해 고려해주는 것이 일반적이다. 이에 본 연구에서는 하상재료의 차폐효과가 부유사의 연직방향 농도분포에 미치는 영향을 살펴보았다. 연구를 수행하기 위해 하상토의 입도분포를 바탕으로 차폐효과를 고려하고 연직방향으로의 유사농도를 계산하는 유사이동모형을 개발하였다. 수치모형의 검증은 실험실 실험자료와의 비교를 통해 수행되었다. 수치모의 결과로부터 차폐효과를 고려하지 않는 경우에는 하상에서의 침식율이 과다하게 산정되는 것으로 나타났으며, 불균질한 하상재료로 구성된 하천에서 부유사의 연직방향 유사농도를 정확하게 계산하기 위해서는 차폐효과에 대한 고려가 필요하다는 결론이 도출되었다.

• Korean Journal of Plant Resources
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• v.23 no.5
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• pp.423-429
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• 2010

In this study, we examined the anti-diabetic activity in vitro by the mixed Korean herb water extracts(JDG) composed of Lycium chinense, Cordyceps militaris, and Acanthopanax senticosus on hepatic glucose-regulating enzyme activities such as glucokinase(GK), acetyl-CoA carboxylase(ACC), and inhibition activity of $\alpha$-glucosidase. The hepatic cytosol fraction of a type II diabetic animal(Goto-Kakizaki rat) was used in GK and ACC activity assays. JDG mixed water extracts significantly increased the hepatic GK and ACC activity. The highest anti-$\alpha$-glucosidase activity was observed in JDG 5 water extract when compared to the acarbose control, inhibitor of $\alpha$-glucosidase. We suggest that Lycium chinense, Cordyceps militaris, and Acanthopanax senticosus mixed water extracts may exert an anti-diabetic activity by enhancing the glucose metabolism and may be used as natural $\alpha$-glucosidase inhibitors in type 2 diabetic conditions.

• Korean Journal of Food Science and Technology
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• v.29 no.1
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• pp.107-114
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• 1997

Various fractions of apple fibers such as crude pulp, total dietary fiber, soluble dietary fiber, and insoluble dietary fiber were prepared and added to the proteose peptone-yeast extract-fildes (PYF) media to see their effects on the growth of type cultures of intestinal bacteria. Most microbes tested in this experiment grew well in PYF media with the soluble dietary fiber of apple than with the insoluble dietary fiber. Especially Bifidobacterium species such as B. adolescentis, B. animalis, B. infantis, B. longum, B. thermophilum showed higher growth in PYF media containing the soluble dietary fiber than other fiber fractions. However, pectin-added media didn't promote the growth of most microbes used in the experiment. In the in vitro mixed culture using rat feces as starter, the addition of the soluble dietary fiber or pectin to the basal medium showed larger proportion of Bifidobacterium species in total bacteria than that of glucose.

• Journal of Soil and Groundwater Environment
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• v.8 no.1
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• pp.27-34
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• 2003

In this study, potential degradation of MTBE and other gasoline oxygenates by pure culture ENV425 and mixed culture isolated from gasoline contaminated soil using butane as the sources of carbon and energy was examined and compared. Butane monooxygenases(BMO) of butane-grown ENV425 and mixed culture generated 1-butanol as a major metabolite of butane oxidation and addition of acetylene, specific inhibitor of monooxygenase, inhibited both butane oxidation and 1-butanol production. The results described in this study suggest that alkanes including propane, pentane, and butane are effectively utilized as a growth substrate to oxidize MTBE cometabolically. And also BTEX compounds could be the potential substrate of the MTBE cometabolism. Cell density also affected on the MTBE degradation and transformation capacity(Tc). Increasing cell density caused increasing MTBE degradation but decreased transformation capacity. Other result demonstrated that MTBE and other gasoline oxygenates, ETBE and TAME, were degraded by butane-grown microorganism.