• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.200-202
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• 1999

This paper describes the optimization problem of real power rescheduling and present an algorithm based linear programming for studying the load-shedding and generation reallocation problem when a portion of the transmission system is disabled and at power flow solution cannot be obtained for the overload of some lines. And in case initial is infeasible, solution could not be converge. So this paper gives an algorithm being lie infeasible quantities within limit. The paper describes a LP-based algorithm to obtain the solution in power dispatch related to overload situations in power system and it is easily extened under various objective. The optimization procedures is based in linear programming with bounded variables and use the multi-segment curve method for a objective function and the validity of the algorithm is verified with two examples : 10-bus system and 57-bus system.

• 생명과학회지
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• 제20권7호
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• pp.1027-1033
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• 2010

맥문동(Liriope platyphylla)은 한국과 중국에서 전통적으로 당뇨, 비만, 뇌신경질환, 천식 등의 치료를 위해 사용 해온 치료제이다. 최근에 이들 맥문동으로부터 새로운 치료제를 개발하려는 노력이 활발히 진행 중이지만 아직도 유력한 치료후보제는 확보되지 않았다. 따라서 본 연구에서는 맥문동의 새로운 추출물을 이용하여 당뇨치료 제로서의 가능성을 평가하기 위하여 새로운 방법으로 10가지 후보물질을 추출하고 이들의 독성과 효능을 평가하였다. 그 결과 10가지 추출물 중에서 LP9M80-H가 인슐린 분비를 가장 많이 촉진하였고 다음으로는 LP-H, LP-M, LP-E과 LP9M80-C 등의 순서로 촉진을 하였으나 나머지는 인슐린 분비를 촉지하지 못하였다. 그러나 이들 물질은 인슐린 분비를 촉진하는 농도에서 강한 세포 독성을 나타내었다. 따라서 이들 물질 중에서 가장 효능이 좋은 LP9M80-H의 치료용 최적농도를 설정하였으며, 대략 100-25 ug/ml가 최적농도로 결정되었다. 이러한 결과는 맥문동 추출물 중에서 LP9M80-H가 췌장 $\beta$-세포의 인슐린 분비능을 유도하는 새로운 당뇨치료 후보물질로서 향후에 사용될 가능성을 시사하고 있다.

• Animal Bioscience
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• 제34권1호
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• pp.56-65
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• 2021

Objective: This study was conducted to investigate the effects of molasses and Lactobacillus plantarum on the ensiling quality and in vitro rumen fermentation of sudangrass silage prepared with or without wilting. Methods: The ensiling experiment, measured with 3 replicates, was carried out according to a 2×4 (wilted stages×additives) factorial treatment structure. Dry matter of the fresh (210 g/kg fresh matter) or wilted (305 g/kg fresh matter) sudangrass were ensiled (packed into 5.0-L plastic jars) without additive (control) or with molasses (M), Lactobacillus plantarum (LP), or molasses + Lactobacillus plantarum (M+LP). After 60 days of ensiling, the silages were analyzed for the chemical, fermentation, and in vitro characteristics. Results: After 60 days of ensiling, the fermentation parameters were affected by wilted, the additives and the interactions of wilted with the additives (p<0.05). The M+LP treatment at wilted had higher lactic acid levels and V-score (p<0.05) but lower pH values and butyric acid concentrations than the other treatments. In comparison with sudangrass before ensiling, after ensiling had lower dry matter and higher non-fibrous carbohydrate. The in vitro gas production, in vitro dry matter digestibility, in vitro crude protein digestibility, and in vitro acid fiber detergent digestibility changed under the effects of the additives. Significant interactions were observed between wilted and the additives in terms of in vitro gas production at 48 h, asymptotic gas production, gas production rate, half time, and the average gas production rate. The total volatile fatty acid levels in the additive treatments were higher than those in the control. Conclusion: Wilting and supplementation with molasses and Lactobacillus plantarum had the ability to improve the ensiling quality and in vitro nutrient digestibility of sudangrass silage. The M+LP treatment at wilted exhibited the strongest positive effects on silage quality and in vitro ruminal fermentation characteristics.

• 월간 기계설비
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• 5호통권202호
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• pp.64-69
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• 2007

소형저장탱크의 보급으로 벌크로리 공급시스템이 확대되고 체계적인 수요관리가 가능해짐에 따라 LP가스산업의 발전에 많은 기여를 할 것으로 기대된다. 또한 500kg미만 소형저장탱크의 고압배관시공에 고압호스가 가능해짐에 따라 2006년 11월 소형저장탱크용 고압호스 성능인증기준이 제정되게 되었다. 새로 제정된 소형저장탱크용 고압호스의 성능인증 기준을 기술하여 고압호스제조업체, 소형저장탱크 시공업체 등의 관련업체에 참고자료가 되기를 바란다.

• 한국안전학회지
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• 제24권2호
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• pp.37-41
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• 2009

PVC hose for gas is used widely in many of places which is used for connector between combustor and gas cock. In this study, it is collected by 5 regional area as Gyeonggi, Jeonnam, Gyeongbuk, Jeju and Gangwon and tested in leakage, hardness, anti-low temperature. As a result, the color on it is started to change rapidly when it is installed. Some of specimen are broken in bending test after keeping in $-25^{\circ}C$, 24hours. It's hardness has a tendency to increase gradually. If hardness of hose is increased, PVC hose is separated easily from cock or combustor so that LP gas or city gas can be escaped. For prevention of gas leakage accidents of PVC hose, the available period of it should be presented.

• 한국경영과학회지
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• 제23권3호
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• pp.135-151
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• 1998

The demand of large capacity in coming cellular systems makes inevitable the deployment of small cells, rendering more frequent handoff occurrences of calls than in the conventional system. The key issue is then how effectively to reduce the chance of unsuccessful handoffs, since the handoff failure is less desirable than that of a new call attempt. In this study, we consider the control policies which give priority to handoff calls by limiting channel assignment for the originating new calls, and allow queueing the new calls which are rejected at their first attempts. On this system. we propose the problem of finding an optimal call control strategy which optimizes the objective function value, while satisfying the requirements on the handoff/new call blocking probabilities and the new call delay. The objective function takes the most general form to include such well-known performance measures as the weighted average carried traffic and the handoff call blocking probability. The problem is formulated into two different linear programming (LP) models. One is based on the direct employment of steady state equations, and the other uses the theory of semi-Markov decision process. Two LP formulations are competitive each other, having its own strength in the numbers of variables and constraints. Extensive experiments are also conducted to show which call control strategy is optimal under various system environments having different objective functions and traffic patterns.

• Tribology and Lubricants
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• 제36권6호
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• pp.371-377
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• 2020

In In this study, we compared the results of a ball bearing life prediction model based on rolling element loads with the results of fatigue life prediction of ball bearings when a stress-based contact fatigue life prediction technique is applied to the ball bearing. We calculate the load acting on each rolling element by the external load of the bearing and apply the result to the Lundberg-Palmgren (LP) theory to calculate ball bearing life based on the rolling element. We also calculate stress-based ball bearing life through contact and fatigue analyses based on contact modeling of the ball and raceway while considering the fatigue test results of AISI 52100 steel. In stress-based life prediction, we use three high-cycle fatigue-determination equations that can predict the fatigue life when multi-axis proportional loads such as rolling-slide contact conditions are applied. These equations are derived from the stress invariant and critical plane methods and the mesoscopic approach. Life expectancy results are compared with those of the LP model. Results of the analysis indicated that the fatigue life was predicted to be lower in the order of the Crossland, Dang Van, and Matake models. Of the three, the Dang Van fatigue model was found to be the closest to the LP life.

• 생명과학회지
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• 제31권12호
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• pp.1110-1119
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• 2021

본 연구의 목적은 LPS가 처리된 RAW 264.7 대식세포에서의 염증 반응이 미세먼지(PM_2.5)에 의해 더욱 증가될 수 있는지를 조사하는 것이다. 이를 위하여 LPS와 미세먼지(PM_2.5)가 단독으로 처리되거나 LPS가 존재하는 조건에서 미세먼지(PM_2.5)가 처리된 RAW 264.7 세포에서 염증 매개변수와 ROS의 생성 정도 및 염증 조절 유전자들의 발현 수준을 조사하였다. 본 연구의 결과에 의하면 세포 독성이 없는 범위에서 LPS가 처리된 세포에서 미세먼지(PM_2.5)는 염증성 매개 인자(NO 및 PGE₂) 및 cytokine (IL-6 및 IL-1β)의 생성 수준이 각각의 단독 처리군에 비하여 매우 증가되었으며. 이는 이들의 생성에 관여하는 유전자들의 전사 및 번역 수준에서의 발현 증가와 연관성이 있었다. 또한, LPS가 처리된 RAW 264.7 세포에 미세먼지(PM_2.5)가 노출되었을 때, 핵에서 NF-κB의 발현이 더욱 증가하였고, 세포질에서는 NF-κB 뿐만 아니라 IκB-α의 발현이 감소되었다. 이러한 결과는 LPS와 미세먼지(PM_2.5)의 단독 처리에 비하여 동시 처리된 경우 NF-κB 신호계의 활성이 더욱 증가하여 염증성 유전자들의 전사 활성촉진에 기여하였음을 의미한다. 나아가 LPS가 처리된 RAW 264.7 세포에서 미세먼지(PM_2.5)에 의해 ROS 생성이 크게 증가되었지만 NF-κB 억제제는 ROS의 생성을 감소시키지 못하였다. 그러나, ROS 생성을 인위적으로 억제하였을 경우, 미세먼지(PM_2.5)에 의해 증가된 염증 매개 인자의 발현 및 생성과 NF-κB의 활성화가 모두 감소되었다. 따라서, 본 연구의 결과는 LPS가 처리된 RAW 264.7 세포에서 미세먼지(PM_2.5)에 의해 유도된 NF-κB 매개 염증반응의 증가는 ROS 생성 의존적 현상임을 시사한다.

• 디지털융복합연구
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• 제13권4호
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• pp.369-375
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• 2015

본 연구에서는 Tween 80/Span 80의 유화계에서, PIC(Phase Inversion Composition) 방법으로, 80 oC에서 화장품용 오일의 나노에멀젼 형성 가능성과 오일의 구조에 따른 나노에멀젼의 안정성에 대하여 평가하였다. 탄화수소 계열의 LP 70, Isopar H 및 Pripure 3759는 모두 입도 분포가 40 nm 내외의 안정한 나노에멀젼을 형성하였다. 직쇄 구조의 실리콘 오일은 불안정한 에멀젼을 형성하였으나 환상 또는 짧은 사슬의 실리콘 오일은 안정한 나노에멀젼을 형성하였다. 에스테르 오일류에서는 분자량이 증가함에 따라 입도가 증가하였고 분자량이 약 450 이상에서는 안정한 나노에멀젼을 얻을 수 없었다. 오일의 친수성과 친유성을 고려하여 계산하는 요구 HLB (Hydrophilic Lipophilic Balance) 값에 대한 나노에멀젼의 입도는 HLB 값이 8-10 정도 범위에서 가장 입도가 작았다.

• 대한의생명과학회지
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• 제25권4호
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• pp.348-356
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• 2019

This study evaluated the dermal cytotoxicity of sodium bromate (NaBrO₃) and the protective effect of Aster tataricus L. (AT) extract against NaBrO₃-induced cytotoxicity in the cultured NIH3T3 fibroblasts. For this study, it was done the antioxidative effects such as electron donating (ED) activity and lipid peroxidation (LP) activity as well as cell viability. NaBrO₃ significantly decreased cell viability in a dose-dependent manner and its XTT₅₀ value was measured at a concentration of 54.4 μM in these cultures. The cytotoxicity of NaBrO₃ was determined as highly-toxic by Borenfreund and Puerner's toxic criteria. The quercetin, antioxidant significantly increased cell viability against NaBrO₃-induced cytotoxicity. Regarding the protective effect of Aster tataricus (AT) L. extract on NaBrO₃-induced cytotoxicity, AT extract significantly increased the cell viability, the ED ability and the inhibitory ability of LP. From these findings, it suggested that the oxidative stress is involved in the cytotoxicity of NaBrO₃, and AT extract effectively protected NaBrO₃-induced cytotoxicity by antioxidative effects. Conclusively, the natural component like AT extract may be a putative therapeutic agent for the diminution or treatment of the cytotoxicity correlated with oxidative stress like hair dye component, NaBrO₃.