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1-methyl-4-phenylpyridinium($MPP^+$)로 유도된 파킨슨병의 세포손상에 대한 황백의 신경세포 보호효과
정영석,정혜미,서운교,Jung, Young-Seok,Jung, Hye-Mi,Seo, Un-Kyo 대한한방내과학회 2009 大韓韓方內科學會誌 Vol.30 No.1
Background and Objective : The prospects for developing an anti-apoptotic natural component or a compound that exerts a neuroprotective effect with few or no side effects for the treatment of neurodegenerative disease appear favorable. In the present study, we evaluated the effects of the methanol extract of Phellodendri Cortex (PC extract) on 1-methyl-4-phenyl pyridinium($MPP^+$)-induced apoptosis in PC-12 cells. Materials and Methods : We used the methanol extract of Phellodendri Cortex (PC extract). PC-12 cells were cultured by RPMZ-1640. We found the PC extract's gene expression (Bax, Bcl-2) by using RT-PCR. We examined the PC extract's protein expression (Bcl-2, Bax, cytochrome c, poly (ADP-ribose) polymerase (PARP), caspase-3) by SDS-PAGE and Western blot. Results : Apoptosis in $MPP^+$-induced PC-12 cells was accompanied by an increased Bax/Bcl-2 ratio, release of cytochrome c to the cytosol and the activation of caspase-3. PC extract inhibited the down-regulation of Bcl-2 and the up-regulation of Bax, as well as the release of mitochondrial cytochrome c into the cytosol. In addition, PC extract attenuated caspase-3 activation and cleavage of poly (ADP-ribose) polymerase (PARP). Conclusion : These results suggest that the neuroprotective potentials of PC extract against $MPP^+$-induced apoptosis can be. at least partially, ascribed to its anti-apoptotic effects in PC-12 cells.
저노이즈형 진동계측 앱을 통한 MEMS 센서의 계측성능분석
정영석,윤성원,Jung, Young-Seok,Yoon, Sung-Won 한국공간구조학회 2017 한국공간구조학회지 Vol.17 No.1
With increasing number construction of high-rise building which has about 40 to 60 floors there have been many kinds of problem which related with usage from vibration. To predict response acceleration, it is important to assess correct natural frequency. However, due to the noise of MEMS sensor, it is difficult to measure dynamic characteristic such as natural frequency when measuring ambient vibration using MEMS sensor within cell phone. Therefore, a comparative analysis on vibration measuring applications was performed after measuring ambient vibration of 2 skyscrappers which have height between 133.5~244.3m that are located in Seoul and Observation tower using I-jishin APP with noise reduction function of MEMS sensor in order to verify the effectiveness of low noise type vibration measurement APP.
무선 단말기 위치 예측 기반의 대역폭 예약을 이용한 멀티미디어 호 수락 알고리즘
정영석,Jung Young-Seok 한국융합신호처리학회 2006 융합신호처리학회 논문지 (JISPS) Vol.7 No.1
In this paper, we proposed the multimedia call admission control algorithm with the bandwidth reservation based on the prediction of wireless terminal's location to guarantee quality of service for multimedia applications in cellular networks. This algorithm aims at minimizing possible errors In predicting the moving direction of terminals using a mobility prediction scheme. This prediction reduces the size of bandwidth reserved redundantly. In order to evaluate the performance of the algorithm, the blocking rate of new calls and the forced termination rate of hand-off calls are measured and compared the results with those of existing schemes. The results of the experiment revealed that the algorithm presented in this paper achieved better performance with lower call blocking rates and forced-termination rates than those of other methods. 본 논문에서는 무선 이동통신망에서 멀티미디어 응용 프로그램의 서비스 품질 보장을 위하여 무선 단말기의 이동성을 예측하기 위하여 무선 단말기 위치 예측에 기반을 둔 대역폭 예약 알고리즘을 제안한다. 제안된 알고리즘은 이동성 예측 기법을 이용하여 단말기의 이동 방향에 대한 예측 오류를 최소화하는 것을 목적으로 한다. 이러한 예측은 불필요하게 중복되어 예약된 대역폭의 크기를 줄인다. 알고리즘의 성능 평가를 위해서, 신규호의 탈락률과 핸드오프호의 강제종료율을 측정하고 기존에 제안된 기법들의 성능 평가 결과와 비교한다. 그 결과 본 논문에서 제시된 알고리즘이 기존의 방법들에 비해 낮은 호 탈락률 및 강제종료율을 가지는 우수한 성능을 나타내었다
무선 센서 네트워크에서 저밀도 센서 노드에 대한 간접 위치 추정 알고리즘
정영석,우매리,김종근,Jung, Young-Seok,Wu, Mary,Kim, Chong-Gun 한국융합신호처리학회 2012 융합신호처리학회 논문지 (JISPS) Vol.13 No.1
센서 네트워크에서의 각 노드들은 지리적 위치에 기반을 둔 정보를 처리해야할 경우에 다양한 방법으로 자신의 위치를 알 수 있다. GPS를 이용한 위치 획득 방법은 전파의 가시성을 요구하므로 위치 정보를 획득할 수 없는 경우가 존재하고 비용이 많이들며, 전력소모가 많다. GPS 없이 센서 노드들의 위치를 알아내는 방법은 복잡한 수학적 알고리즘을 요구하며, 위치 추정의 정확도 측면에서 불리하다는 단점을 가지고 있다. AHLoS는 GPS를 이용한 위치 측정과 위치 추정 알고리즘을 모두 사용하는 혼합 방식이다. AHLoS에서 GPS 노드는 GPS로부터 수신한 자신의 위치를 자신과 인접한 GPS 기능이 없는 일반 노드로 방송한다. 일반 노드는 최소한 3개 이상의 이웃 노드의 위치 정보를 수신할 경우 삼각 측량 위치 계산 알고리즘의 반복 수행을 통해 자신의 위치를 계산할 수 있다. 그러나, 센서 네트워크에서 노드 이동성 네트워크 밀도 지리적 조건에 따라 노드가 3개 이상의 이웃 신호를 수신하지 못할 경우가 존재한다. 본 연구에서는 GPS 노드로부터 위치 정보를 3개 이상 직접 수신하기 어려운 저밀도 환경에서 각 센서 노드가 간접적으로 자신의 위치를 획득하는 방법을 제안한다. Each sensor node can know its location in several ways, if the node process the information based on its geographical position in sensor networks. In the localization scheme using GPS, there could be nodes that don't know their locations because the scheme requires line of sight to radio wave. Moreover, this scheme is high costly and consumes a lot of power. The localization scheme without GPS uses a sophisticated mathematical algorithm estimating location of sensor nodes that may be inaccurate. AHLoS(Ad Hoc Localization System) is a hybrid scheme using both GPS and location estimation algorithm. In AHLoS, the GPS node, which can receive its location from GPS, broadcasts its location to adjacent normal nodes which are not GPS devices. Normal nodes can estimate their location by using iterative triangulation algorithms if they receive at least three beacons which contain the position informations of neighbor nodes. But, there are some cases that a normal node receives less than two beacons by geographical conditions, network density, movements of nodes in sensor networks. We propose an indirect localization scheme for low-density sensor nodes which are difficult to receive directly at least three beacons from GPS nodes in wireless network.
휴대폰 애플리케이션을 통한 초대형 구조물의 동적특성 분석
정영석,윤성원,Jung, Young-Seok,Yoon, Sung-Won 한국공간구조학회 2015 한국공간구조학회지 Vol.15 No.4
The serviceability design of the high-rise building is affected by the wind response vibration such as the acceleration, at this time it is important to calculate the natural frequency correctly. Since the suggestion equation of the natural frequency being used in the design phase is not the regression equation obtained from the vibration measurement of the high-rise building, the verification to use for the serviceability design of the high-rise building is necessary. This thesis conducted an ambient vibration measuring on the high-rise building through the mobile-phone application to calculate the natural frequency and suggested a natural frequency approximate expression following the building's height, and compared with the domestic/foreign standard and the result of the eigen-value analysis.
정영석,윤성원,Jung, Young-Seok,Yoon, Sung-Won 한국공간구조학회 2016 한국공간구조학회지 Vol.16 No.4
Recently, with development of city traffic network planning, there are various effects with living space from vibration of railway. But, study which about effect from vertical vibration in floor slab in nearing structure is lack in nowadays. This thesis have analysed result from acceleration response per distance as well as proceed with serviceability evaluation and extracted natural frequency from measuring vibration of railway using mobile phone application which is oriented for building which have distances about 5m to 22m from railway.
정영석(Jung Young-seok),강기환(Kang Gi-hawn),유권종(Yu Gwon-jong),송진수(Song Jin-soo) 전력전자학회 1998 전력전자학술대회 논문집 Vol.- No.-
In recent years, for the viewpoint of environment and electric power demand for stable secure, new energy such as photovoltaic system (PV) become increasingly popular. In case of interconnecting PV to the commercial electric company, two problems will occur when operating in isolation with the other general consumers. One is doing harm to the power quality. And the other is the security problem caused by char ching a part of commercial system line that has to be no voltage. In this paper, a simple modelling of distribution system and grid -connected PV system and simulation result were proposed.<br/> <br/>
불완전한 정보하에서 역선택 모형을 이용한 “서민금융” 시장의 이해
정영석 ( Young Seok Jung ),이기영 ( Ki Young Lee ) 한국금융연구원 2011 금융연구 Vol.25 No.3
Although there were many researches about financial access and availability of credit for less creditworthy individuals recently in Korea, they focused mostly on the institutional aspect of the lending market, and rigorous economic analyses were not provided enough to support policies in that area. Purpose of this paper is to provide a theoretical framework to analyze the subprime lending market for less creditworthy individuals, by extending the historical research of Stiglitz and Weiss (1981) on the credit rationing. The original model of credit rationing was extended by incorporating lender`s decision making process under imperfect information, and this paper identified specific conditions of adverse selection that can cause credit allocation. Also, it is shown that the identified conditions of the adverse selection coincide with characteristics of less creditworthy borrowers. Based on the applied lending market model, the authors provide theoretical explanation on important issues in this market. In chapter 2, lender`s revenue function is defined under the assumption of imperfect information, and supply curve is derived. Unique aspect of this paper is that it incorporates credit approval process including type II error and competition in the lending market. Based on the model, it is proved that the possibility of strong form adverse selection increases as 1) default rate increases, 2) loan interest rate increases, 3) type II error of credit decision model increases, 4) market competition for good credit individual increases, 5) collateral and recovery rate decreases. All those conditions for adverse selection are very much consistent with characteristics of the less creditworthy borrower group. Also, threshold interest rate for adverse selection is derived. Chapter 3 performs a comparative analysis of lender`s profit and lending market equilibrium assuming three borrower groups with different level of creditworthiness. Based on the analysis of the threshold interest rate of adverse selection, lender`s revenue curve for good credit borrowers in relation with interest rate is always located above that of the less creditworthy borrowers. Also, the threshold interest rate into adverse selection is always higher for good credit borrowers, than that of the less creditworthy borrowers. Thus, in the lending market for good credit borrowers, there is no possibility of adverse selection in the observable range of interest rate, and lenders have capability to price their credit risk. In this case, despite lender`s incentive to increase interest rate, it is constrained by market competition at normal profit level. For the third group of bad credit borrowers, it is very likely that the maximum level of revenue function is positioned below the cost of lending, and no credit is provided at all. The second group of less creditworthy borrowers could be positioned in the state of credit allocation. Depending upon the cost structure, competitive lenders provide credit for the second group. But, because of the possibility of adverse selection, credit allocation occurs. If credit market works under normal market environment without adverse selection, credit should be provided to a certain level that matches demand, through pricing mechanism of interest rate, whether it is good or bad credit. But under imperfect information, lender`s inability to price the risk causes two unique situations, 1) credit is not supplied at all, like in the bad credit group, and 2) excess demand exists like in the second less creditworthy group. In Chapter 4, authors discuss important issues related with less creditworthy borrower`s, using the theoretical model developed in previous chapters. 1) Low interest rate environment makes lenders more accessible to the subprime lending market which was not served by them previously. 2) Large gap in the interest rates charged to less creditworthy borrowers could be explained by excess demand in the market, and less prudent lenders could take advantage of this situation to increase short term profit. 3) Overall supply of credit can result in asymmetric impact between good credit and less creditworthy borrowers, and widen the interest rate gap between the two groups. 4) The most fundamental approach to improve access to credit is to enhance credit decision capability of lenders and mitigate information imperfection. 5) The operating cost has important implication in this market as a lender`s capability to serve this market is affected very much by operating cost, and it explains a big portion of the total cost of lending because of small loan size.