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A Note on the Estimation and Testing in the Switching Regression Models
Hong, Chansik 淑明女子大學校 經濟經營硏究所 1996 經濟經營論集 Vol.26 No.-
Hong(1995) suggested an EM algorithm to compute the maximum likelihood estimates for a switching regression model with time varyng switching probabilities. This note provides the proof that the algorithm leads to the maximum likelihood estimates. In the switching regression model, the dependent variable(y_t) is assumed to be generated by one of the two regimes with certain probabilities. However, information of which regime generated each observation is not available. The extended switching regression model considered by Hong(1995) allows the switching probabilities to vary over time depending upon the realizations of some independent variables.
Ha, Kotdaji,Kim, Sung-Young,Hong, Chansik,Myeong, Jongyun,Shin, Jin-Hong,Kim, Dae-Seong,Jeon, Ju-Hong,So, Insuk Korean Society for Molecular and Cellular Biology 2014 Molecules and cells Vol.37 No.3
ClC-1 is a member of a large family of voltage-gated chloride channels, abundantly expressed in human skeletal muscle. Mutations in ClC-1 are associated with myotonia congenita (MC) and result in loss of regulation of membrane excitability in skeletal muscle. We studied the electrophysiological characteristics of six mutants found among Korean MC patients, using patch clamp methods in HEK293 cells. Here, we found that the autosomal dominant mutants S189C and P480S displayed reduced chloride conductances compared to WT. Autosomal recessive mutant M128I did not show a typical rapid deactivation of Cl- currents. While sporadic mutant G523D displayed sustained activation of $Cl^-$ currents in the whole cell traces, the other sporadic mutants, M373L and M609K, demonstrated rapid deactivations. $V_{1/2}$ of these mutants was shifted to more depolarizing potentials. In order to identify potential effects on gating processes, slow and fast gating was analyzed for each mutant. We show that slow gating of the mutants tends to be shifted toward more positive potentials in comparison to WT. Collectively, these six mutants found among Korean patients demonstrated modifications of channel gating behaviors and reduced chloride conductances that likely contribute to the physiologic changes of MC.
시료 중 잔류 항생제 분석 방법: I. 고상 시료 전처리 방법
김찬식 ( Chansik Kim ),류홍덕 ( Hong-duck Ryu ),정유진 ( Eu Gene Chung ),김용석 ( Yongseok Kim ),류덕희 ( Doug Hee Rhew ) 한국물환경학회(구 한국수질보전학회) 2016 한국물환경학회지 Vol.32 No.6
Korea is one of the countries with a large market of veterinary antibiotics, although antimicrobial resistance in bacteria is becoming a serious issue in many countries. Korean government started to be interested in estimation of effects of livestock manure on rivers and agricultural soils and in monitoring heavy metals, organic pollutants and antibiotics in the water and soil samples. In this paper, pre-treatment methods to separate the selected antibiotics from the solid samples were reviewed. It is essential to select an efficient and proper procedure for the pre-treatment due to the high portion of proteins and organics in biosolid samples. The pre-treatment consists of extraction followed by clean-up. Initially, homogenized samples were extracted by sonication, mechanical agitation or pressurized liquid extraction with methanol/acetonitrile/water mixture under acidic/base depending on compounds. However, aminoglycosides and colistin were extracted with 5% trichloroacetic acid and HCl, respectively. Since the β-lactams are easily decomposed in acidic and basic condition, these were extracted in neutral pH. Filtration with membrane (pore size, 0.2 μm) or solid phase extraction with HLB and methanol, as eluent, were normally applied for the clean-up. More than three pre-treatment procedures should be adopted to screen all the selected antibiotics in solid samples.
이화학적 특성과 질소 안정동위원소비를 활용한 강우시 가축사육 밀집 지역의 하천 수질 영향 평가
류홍덕 ( Hong-duck Ryu ),백운일 ( Un-il Baek ),김선정 ( Sun-jung Kim ),김덕우 ( Deok-woo Kim ),김찬식 ( Chansik Kim ),김민섭 ( Min-seob Kim ),신동석 ( Dongseok Shin ),이재관 ( Jae-kwan Lee ),정유진 ( Eu Gene Chung ) 한국환경과학회 2019 한국환경과학회지 Vol.28 No.1
This study aimed to assess the impact of livestock excreta discharged from an Intensive Livestock Farming Area (ILFA) on river water quality during a rainfall event. The Bangcho River, which is one of the 7 tributaries in the Cheongmi River watershed, was the study site. The Cheongmi River watershed is the second largest area for livestock excreta discharge in Korea. Our results clearly showed that, during the rainfall event, the water quality of the Bangcho River was severely deteriorated due to the COD, NH<sub>4</sub>-N, T-N, PO<sub>4</sub>-P, T-P, and heavy metals (Cu, Zn, and Mn) in the run-off from nearby farmlands, where the soil comprised composted manure and unmanaged livestock excreta. In addition, stable isotope analysis revealed that most of nitrogen (NH<sub>4</sub>-N and NO<sub>3</sub>-N) in the run-off was from the ammonium and nitrate in the livestock excreta. The values of δ<sup>15</sup>N<sub>NH4</sub> and δ<sup>15</sup>N<sub>NO3</sub> for the Bangcho River water sample, which was obtained from the downstream of mixing zone for run-off water, were lower than those for the run-off water. This indicates that there were other nitrogen sources upstream river in the river. It was assumed from δ<sup>15</sup>N<sub>NH4</sub> and δ<sup>15</sup>N<sub>NO3</sub> stable isotope analyses that these other nitrogen sources were naturally occurring soil nitrogen, nitrogen from chemical fertilizers, sewage, and livestock excreta. Therefore, the use of physicochemical characteristics and nitrogen stable isotopes in the water quality impact assessment enabled more effective analysis of nitrogen pollution from an ILFA during rainfall events.
ATM망에서 음성 신호원의 묵음구간을 고려한 효율적인 셀 접속 방안
홍진근(JinKeun Hong),황찬식(Chansik Hwang) 한국정보과학회 1997 한국정보과학회 학술발표논문집 Vol.24 No.2Ⅲ
음성 서비스의 각 클래스의 유형은 ATM상에서 제공되는 비트율에 따라 분류되고 있다. 항등 비트율의 신호원으로 종단간의 타이밍을 요구하는 전화와 같은 single 고압축 음성 채널이나 Nx64Kbps급의 음성 채널의 경우 ATM과의 상호 접속을 위해서는 셀 조립 분해기(CLAD)를 통한 상호 접속 과정이 요구되며 이러한 경우 하나의 셀에 다수의 음성 트래픽을 매핑하여 전송하게 된다. 이때 발생하는 셀 조립/분해 과정의 지연 시간은 셀 패킹법에 의해 결정되며 전송 망 자원의 효율의 증대와 지연을 고려한 효율적인 셀 조립/분해 방안이 요구된다. 따라서 본 논문에서는 항등 비트율 트래픽 신호원이 ATM망과의 접속시 신호원의 묵음/유음의 형태에 대해 보다 적합한 접속 방안을 제시하였으며, 제안한 방안은 묵음 구간에서 단위 셀당 조립 지연시간이 채널 유/무 상태를 지시하는 지시정보를 할당하는 접속방안보다 4배 정도의 단축 지연시간과 유음 구간에서 20%정도의 단축 지연시간의 성능 개선을 나타내었다.