Effects of Mitochondrial Inhibitors on Cell Viability in U937 Monocytes Under Glucose Deprivation

Mijin Han,임동순 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.6

We studied cytotoxic mechanism of mitochondrial inhibitors in U937 cells. U937 cells were sensitive to cytotoxicity of mitochondrial inhibitors under glucose deprivation condition, whereas PC12 neuronal cells were not. In glucose deprivation condition, intracellular ATP content is decreased and thereby AMP-activated protein kinase (AMPK) is activated. And also activation of JNK, inactivation of ERK, and enhanced expression of Bcl-2 were observed. Mitochondrial inhibitors such as rotenone, TTFA, antimycin A, sodium azide, oligomycin, and valinomycin were used in this study. Inhibitors did not much influence intracellular ATP contents and activity of AMPK under glucose deprivation condition. Activities of Akt and p38 MAPK, however, were decreased by the inhibitors under glucose deprivation condition except TTFA. Furthermore, intracellular Ca2+ concentration was also greatly increased by the inhibitors. Finally, mitochondrial membrane potential was decreased by the inhibitors but TTFA increase the potential and oligomycin maintains it. In the present study, results suggest that under glucose deprivation condition mitochondrial inhibitors may induce severe cytotoxicity of U937 cells through inhibition of Akt and p38 MAPK, increase of [Ca2+]i, and decrease of MMP, but not through inhibition of ATP production and activation of AMPK

THE VALUATION OF TIMER POWER OPTIONS WITH STOCHASTIC VOLATILITY

Mijin HAN,DONGHYUN KIM,안세륭,윤지훈 한국산업응용수학회 2022 Journal of the Korean Society for Industrial and A Vol.26 No.4

Timer options are one of the contingent claims that, for given the variance budget, its payoff depends on a random maturity in terms of the realized variance unlike the standard European vanilla option with a fixed time maturity. Since it was first launched by Societ´ e´ Gen´ erale Corporate and Investment Banking in 2007, the valuation of the timer options under ´ several stochastic environment for the volatility has been conducted by many researches. In this study, we propose the pricing of timer power options combined with standard timer options and the index of the power to the underlying asset for the investors to actualize lower risks and higher returns at the same time under the uncertain markets. By using the asymptotic analysis, we obtain the first-order approximation of timer power options. Moreover, we demonstrate that our solution has been derived accurately by comparing it with the solution from the MonteCarlo method. Finally, we analyze the impact of the stochastic volatility with regards to various parameters on the timer power options numerically.

한우농가의 최적 출하월령 선택:

한미진(Han Mijin) 한국농업경제학회 2017 農業經濟硏究 Vol.58 No.4

This study analyzes the optimal replacement time of Hanwoo cattle using a dynamic programming model. The model determines economically optimum culling time of an individual cow or steer with considering the farmer’s risk aversion and different levels of price. As a result of the analysis, we found that the optimal time is 30-31 months for steer, and that the higher the price, the sooner the replacement. When considering risk aversion, the relative value declines but does not affect the sell decision. The results also indicate that the optimal time to sell a cow is after 44-69 months(or 2-4 parity). The higher price of the cow or the lower price of the calf, the more advantageous it is to quickly replace the cow. Also, the impact of the calf price is bigger than the cow price. As in the case of steer, risk aversion reduces the relative value but does not have a significant effect on the decision.

베이지안 메타분석을 이용한 우리나라 강·하천의 환경적 가치

한미진 ( Mijin Han ) 한국환경경제학회·한국자원경제학회(구 한국환경경제학회) 2018 한국환경경제학회 학술발표논문집 Vol.2018 No.하계

환경재의 가치평가는 그간 환경경제학 분야에서 꾸준히 관심을 가지고 있던 문제이다. 그러나 국내에서 축적된 가치추정 연구를 바탕으로 통합된 하나의 가치추정치를 분석하고자 하는 연구는 거의 없었으며, 그동안 시도된 메타분석 역시 편익이전을 위한 중간단계로만 고려되었고 추정치의 수가 충분하지 않은 경우 통계적 유의성을 확보하기 어렵다는 문제가 있었다. 따라서 본 연구에서는 이러한 문제점을 베이지안 3단계 계층적 메타분석과 베이지안 메타회귀분석을 적용하여 극복하고자 하였다. 강·하천의 환경적 가치를 추정한 국내 선행연구를 바탕으로 베이지안 메타분석을 적용하여 강과 하천의 환경가치를 추정한 결과 전체 강/하천에 대한 지불의사는 베이지안 3단계 계층적 메타분석에서 37,860원/년/가구, 베이지안 메타회귀분석에서는 34,740원/년/가구로 추정되었다. 유역별로는 한강과 금강이 상대적으로 높은 지불의사를 나타내었으며, 서식지제공이나 생물다양성, 경관미 기능과 같은 간접적 수요를 갖는 환경서비스에 비해 수질이나 수량과 같이 직접적 수요를 나타내는 환경서비스에 대한 지불의사가 확연히 높은 것을 확인할 수 있었다. 베이지안 3단계 계층적 메타분석 결과를 바탕으로 우리나라 강/하천의 환경적 가치를 추정한 결과 연간 총 8,189억 1,180만원의 가치를 가지는 것으로 분석되었으며, 베이지안 메타회귀분석에서는 연간 총 7,628억 9,010만원의 가치를 갖는 것으로 분석되었다. Environmental valueation is the issue that has consistently interested in the academia. However, there was almost no study of evaluate a single significant value, and the some results of existing meta analysis are not significant when the number of the sample is not enough. This study estimates the environmental values of the rivers and the streams in South Korea by applying Bayesian meta-analysis based on the previous researches evaluating environmental values of the rivers and the streams. This study intends to overcome the drawback by using a Bayesian three-step hierarchical meta-analysis and a Bayesian meta-regression. As the results, willingness to pay for the rivers and the streams presents ₩37,860(₩/year/household) and ₩34,740(₩/year/household) in a Bayesian three-step hierarchical meta-analysis and Bayesian meta-regression, respectively. The results in Meta analysis show that the willingness to pay for the Han river and Geum-gang river were relatively high. Also, The willingness to pay for the environmental service, representing direct demand such as water quality and quantity is significantly higher than that of indirect demand such as habitat, biodiversity, and view. Based on the results of a Bayesian three-step hierarchical meta-analysis, the environmental value of river/stream was estimated to be 818 billion won per year, and based on the Bayesian meta-regression analysis, it was 763 billion won per year.

Effect of Temperature and Plow Pan on Water Movement in Monolithic Weighable Lysimeter with Paddy Sandy Loam Soil during Winter Season

Mijin Seo,Kyunghwa Han,Kangho Jung,Heerae Cho,Yongseon Zhang,Seyeong Choi 한국토양비료학회 2016 한국토양비료학회지 Vol.49 No.4

The monolithic weighing lysimeter is a useful facility that could directly measure water movement via layers, drainage, and evapotranspiration (ET) with precise sensors. We evaluated water movement through layers and water balance using the lysimeter with undisturbed paddy sandy loam soil, Gangseo soil series (mesic family of Anthraquic Eutrudepts classified by Soil Taxonomy) during winter season from Dec. 2014 to Feb. 2015. Daily ET indicated up to 1.5 mm in December and January and 2 mm in February. The abrupt increase of soil water tension at the depth of 0.1 m, when soil temperature at the same depth was below 2°C, was observed due to temporary frost heaving. The surface evaporation was less than reference ET below -15 kPa of soil water potential at the depth of 0.1 m. The maximum drainage rate was similar to the saturated hydraulic conductivity of a plow pan layer. Both upward and downward water movement, related to ET and drainage, were retarded by a plow pan layer. This study demonstrated that the lysimeter study could well quantify water balance components even under frost heaving during winter season and that a plow pan with low permeability could act as a boundary that affects drainage and evapotranspiration.

Modeling Low Impact Development practices (LIDs) under different development designs using SWAT

Mijin Seo(서미진),Fouad Jaber,Kyunghwa Han,Heerae Cho(조희래) 한국토양비료학회 2016 한국토양비료학회 학술발표회 초록집 Vol.2016 No.10

Effects of no-tillage and shallow tillage on soil water and evapotranspiration using weighing lysimeter with different soil conditions

Mijin Seo(서미진),Kyunghwa Han(한경화),Kangho Jung(정강호),Heerae Cho(조희래 ),Se-yeong Choi(최세영) 한국토양비료학회 2016 한국토양비료학회 학술발표회 초록집 Vol.2016 No.10

MWCNT/Fibrin Bionanocomposites by in situ Enzymatic Polymerization

Mijin Kim,Jun Ho Jang,Jung Hun Han,Yong-Won Lee,Sang-min Cho,Sung-Yong Son,John Hulme,최인성,Hyun-jong Paik,안성수 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.2

In this work multiwalled carbon nanotube (MWCNT)/fibrin hybrid structures were synthesized via the transglutaminase- catalyzed polymerization of fibrinogen (FBG). Specifically, FBG was tethered onto oxidized MWCNTs by amide coupling, and the in situ polymerization of FBG to fibrin was performed by plasma transglutaminase (Factor XIIIa) in the presence of thrombin. The attached FBG was found to be biologically active and was polymerized to fibrin by thrombin and Factor XIIIa. MWCNT-FBG and MWCNT-Fibrin structures were characterized by FT-IR spectroscopy, transmission electron microscopy, and energy-dispersive X-ray (EDX) spectroscopy.

The Effect of the Community Mobility on the COVID-19 Pandemic

Mijin Noh(노미진),Mu Moung Cho Han(한무명초),Yang Sok Kim(김양석),Tazizur Rahman(타지주르라만) 한국로고스경영학회 2021 로고스경영연구 Vol.19 No.3

코로나19로 인해 일상생활의 어려움을 겪게 되면서 코로나19 확산을 방지하기 위한 다양한 정책들이 나오고 있으며, 이와 관련된 다양한 연구들이 진행되고 있다. 본 연구는 코로나19에 대한 연구를 수행하였으며, 연구의 목적을 살펴보면 다음과 같다. 첫째, 인구 이동성이 코로나19 확산에 미치는 영향력을 살펴본다. 식품점 및 약국, 공원, 주거지, 소매점 및 여가시설, 직장과 대중교통 정거장과 같은 장소에서의 인구 이동성과 코로나19 확진자 증가와의 관련성을 살펴본다. 둘째, 코로나19 확진자의 증가가 코로나19 사망자의 증가와의 관련성을 살펴본다. 마지막으로 장소별 인구 이동성과 코로나19 확진자 사이에 대중교통 정거장의 매개효과를 살펴본다. 본 연구를 수행하기 위하여 구글의 인구 이동성 데이터와 코로나19 관련 데이터를 활용하였다. 분석 결과를 보면 인구 이동성의 증가는 코로나19 확진자의 수를 증가시키고, 코로나19 확진자 수의 증가는 사망자 수를 증가시킨다. 본 연구의 결과는 코로나19 확산을 억제하기 위한 정부 정책 수립을 할 때에 유용한 자료로 활용할 수 있을 것이다. As daily life suffers from COVID-19, various policies are emerging to prevent the spread of COVID-19, and various studies related to COVID-19 are ongoing. The purposes of this study are as follows. First, we examine the impact of population mobility on the spread of COVID-19. We examine the relationship between mobility and COVID-19 confirmed cases such as food stores and pharmacies, parks, residential areas, retail stores and recreational facilities, workplaces, and public transport stops. Second, we examine the relationship between COVID-19 confirmed cases and their deaths. Finally, we investigate the mediating effect of public transport stops between mobility and COVID-19 confirmed cases. To carry out this study, we used Google’s population’s mobility data and COVID-19 data. The results of this study could provide useful guidelines when establishing government policies for COVID-19.

Interpreting in situ Soil Water Characteristics Curve under Different Paddy Soil Types Using Undisturbed Lysimeter with Soil Sensor

Mijin Seo,Kyunghwa Han,Heerae Cho,Junghun Ok,Yongseon Zhang,Youngho Seo,Kangho Jung,Hyubsung Lee,Gisun Kim 한국토양비료학회 2017 한국토양비료학회지 Vol.50 No.5

The soil water characteristics curve (SWCC) represents the relation between soil water potential and soil water content. The shape and range of SWCC according to the relation could vary depending on soil characteristics. The objective of the study was to estimate SWCC depending on soil types and layers and to analyze the trend among them. To accomplish this goal, the unsaturated three soils were considered: silty clay loam, loam, and sandy loam soils. Weighable lysimeters were used for exactly measuring soil water content and soil water potential. Two fitting models, van Genuchten and Campbell, were applied. Two models entirely fitted well the measured SWCC, indicating low RMSE and high R² values. However, the large difference between the measured and the estimated was found at the 30 cm layer of the silty clay loam soil, and the gap was wider as soil water potential increased. In addition, the non-linear decrease of soil water content according to the increase of soil water potential tended to be more distinct in the sandy loam soil and at the 10 cm layer than in the silty clay loam soil and at the lower layers. These might be seen due to the various factors such as not only pore size distribution, but also cracks by high clay content and plow pan layers by compaction. This study clearly showed difficulty in the estimation of SWCC by such kind of factors.