주의력결핍-과잉행동장애를 동반한 알코올 의존환자들의 특성 : 임상적/유전학적 자료분석

김붕년,손기현,전지현,곽욱환,유희정,조수철,박철수 大韓神經精神醫學會 2003 신경정신의학 Vol.42 No.3

Objectives : This study was conducted to estimate the comorbidity rate of ADHD in a group of patients with alcohol dependency and to find out the characteristics of alcoholic patients with ADHD using the diverse clinical and genetic variables. Methods : Eighty five patients with alcohol dependency were recruited from 4 mental hospitals in Kyoung-Nam and Kyoung-Ki province. For the evaluation of ADHD symptoms in both childhood and adulthood, the highly structured Diagnostic Interview Schedule for Children-IV (DISC-FV)-ADHD module was used. The various standardized scales and questionnaires were also applied to evaluate the comorbid conditions and psychopathological status. All the subjects' blood was collected and genetic study for the polymorphism of DRD2, TH, 5-HTTLPR, COMT, ALDH2 was performed. Results : 1) The comorbid rate of definite ADHD in alcoholic patients was 38% (28/85). 2) The frequency of unmarried status was significantly higher in ADHD group compared non-ADHD group. 3) The onset of pathologic drinking and auditory hallucination was significantly earlier in ADHD group than non-ADHD alcholic group. 4) In ADHD alcoholic group, antisocial behavior was more frequently reported, and the score of co-dependency scale, depression/anxiety, aggression and obsessive compulsive drinking scales were significantly higher compared to non-ADHD alcoholic group. 5) No signficant difference was found in the frequency of polymorphic alleles in COMT, DRD2, 5-HTTLPR, ALDH2, TH between ADHD and non-ADHD alcoholic group. Conclusion : In alcoholic patients, the rate of adult type ADHD was higher than expected rate in general population. The alcoholic patients with ADHD suffered from more sever degree of alcohol dependency and earlier alcohol related problems. ADHD-alcoholic group showed higher diverse comorbid psychopathology and lower marital status compared to non-ADHD-alcoholic group. No difference, however, was found in genetic data between two groups.

Machine Learning Approach for Simultaneous Determination of Counting Efficiencies of Strontium-90 and Strontium-89

Wook Sohn,Kahee Jeong,Ji-eun Park,Sooyeon Lim 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1

Radioactivity of radiostrontiums, Sr-89 and Sr-90, which are both pure beta-emitters, are generally measured via Cherenkov counting. However, the determination of Cherenkov counting efficiencies of radiostrontiums requires a complicated procedure due to the presence of Y-90 (also a pure betaemitter) which is the daughter nuclide of Sr-90. In this study, we have developed a machine learning approach using a linear regression model which allows an easier and simultaneous determination of the Cherenkov counting efficiencies of the radiostrontiums. The linear regression model was employed because total net Cherenkov count (Ct) from the three beta-emitters at time t after the separation of Y- 90, can be expressed as a linear combination of their respective time-varying radioactivities with their respective coefficients (parameters) being their counting efficiencies: Ct = εSr-90[ASr-90·exp(–λSr-90·t)] + εSr-89[ASr-89·exp(–λSr-89·t)] + εY-90[ASr-90·exp(1–λSr-90·t)], where ε is a counting efficiency, A is an initial activity, λ is a decay constant and t is time after the separation of Y-90, Thus, if we train the model with multiple Cherenkov counts measured from the three beta emitters, then we can obtain their estimates for counting efficiencies (so-called parameters) straightforward. For this, the model has been trained by two methods: Ordinary Least Squares (OLS) and Bayesian linear regression (BLR), for which two software packages, PyMC3 and Stan were employed to compare their performances. The results showed that the accuracy of the OLS was worse than that of the BLR. Particularly, the counting efficiency of Sr-90 was estimated to be smaller than 0, which is an unrealistic value. On the other hand, the estimates of the BLR gave realistic values which are close to the true values. Additionally, the BLR was able to provide a distribution for each counting efficiency (so-called “posterior”) from which various types of inference can be made including median and credible interval in the Bayesian statistics which is analogous to, but different from confidence interval in the Frequentist statistics. In the results of the BLR, the Stan package gave more accurate estimates than the PyMC3 package. Therefore, it is expected that counting efficiencies of the radiostrontiums including radioyttrium can be determined at the same time, more easily and accurately, by using the BLR with the Stan package and that the activities of radiostrontium also can be determined more easily by using the BLR if we know their counting efficiencies in advance. It is worth noting that the usage of the linear regression model in this study was different from the usual one where the trained model is used to predict a response value (count) from a set of unseen regressor values (activities).

The Effect of Supervisory Power and Institutions on the Banking Sector Stability in the Post-Crisis Era

Wook Sohn,Iegor Vyshnevskyi 한국재무학회 2023 財務硏究 Vol.36 No.2

An Equity Market Perspective of the Korean Financial Crisis

Wook Sohn,Bobae Choi 한국재무학회 2009 한국재무학회 학술대회 Vol.2009 No.08

We examine the movement of Korean stock prices before and after the 1997 financial crisis. In contrast to the case of Japan documented by Hamao, Mei and Xu (2005), we find an increase in firm-level volatility. The results appear to derive from government efforts to restructure the corporate sector, specifically Chaebol firms, immediately after the market crash.

An Equity Market Perspective of the Korean Financial Crisis

Wook Sohn,Bo Bae Choi 한국경영학회 2009 한국경영학회 통합학술발표논문집 Vol.2009 No.08

Case Study: A Bayesian Approach to Updating Scaling Factor for Radwaste

Wook Sohn,Jieun Park,Kahee Jeong,Sooyeon Lim 한국방사성폐기물학회 2024 한국방사성폐기물학회 학술논문요약집 Vol.22 No.1

Extraction of Uranium Using Thermal Discharge of Domestic Nuclear Power Plants

Wook Sohn,Jieun Park 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

Given the limited terrestrial reserves of uranium (approximately 4.6 million tons), exploring alternative resources is necessary to secure a sustainable, long-term supply of nuclear energy. Uranium extraction from seawater (UES) is a potential solution since the amount of uranium dissolved in seawater (approximately 4.5 billion tons) is about 1,000 times that of terrestrial reserves. However, due to the ultra-low concentration of uranium in seawater (approximately 3.3 ppb), making UES economically viable is a challenging task. In this paper, we explore the potential of using thermal discharge from domestic nuclear power plants for uranium extraction. The motivation for this comes from previous research showing that the adsorption capacity of amidoxime-based adsorbents is proportional to the temperature of the seawater in which they are deployed. Specifically, a study conducted in Japan found that a 10°C increase in seawater temperature resulted in a 1.5-fold increase in adsorption capacity.

Band Alignment at Au/MoS₂ Contacts: Thickness Dependence of Exfoliated Flakes

Sohn, Ahrum,Moon, Hankyoul,Kim, Jayeong,Seo, Miri,Min, Kyung-Ah,Lee, Sang Wook,Yoon, Seokhyun,Hong, Suklyun,Kim, Dong-Wook American Chemical Society 2017 The Journal of Physical Chemistry Part C Vol.121 No.40

<P>We investigated the surface potential (V-surf) of exfoliated MoS2 flakes on bare and Au-coated SiO2/Si substrates using Kelvin probe force microscopy. The V-surf of MoS2 single layers was larger on the Au-coated substrates than on the bare substrates; our theoretical calculations indicate that this may be caused by the formation of a larger electric dipole at the MoS2/Au interface leading to a modified band alignment. V-surf decreased as the thickness of the flakes increased until reaching the bulk value at a thickness of similar to 20 nm (similar to 30 layers) on the bare and similar to 80 nm (similar to 120 layers) on the Au-coated substrates, respectively. This thickness dependence of V-surf was attributed to electrostatic screening in the MoS2 layers. Thus, a difference in the thickness at which the bulk V-surf appeared suggests that the underlying substrate has an effect on the electric-field screening length of the MoS2 flakes. This work provides important insights to help understand and control the electrical properties of metal/MoS2 contacts.</P>

Too Many To Fail : The Effect of Regulatory Forbearance on Market Discipline

Wook Sohn,Hyosoon Choi 한국재무학회 2012 한국재무학회 학술대회 Vol.2012 No.09

This paper investigates whether regulatory forbearance for savings banks in Korea affects the market discipline of depositors using data from 2000 to 2010, which are characterized by a series of exits of savings banks. We find that depositors’ sensitivity to the savings banks’ asset quality decreases when there is regulatory forbearance for failing savings banks. This forbearance effect is also observed in the behavior of the depositors of the neighboring savings banks in the same business area. These results suggest that regulatory forbearance may cause depositors to misjudge bank risks, increasing the expected costs of bank failure.

Atopy May Be an Important Determinant of Subepithelial Fibrosis in Subjects with Asymptomatic Airway Hyperresponsiveness

Sohn, Seong-Wook,Chang, Yoon-Seok,Lee, Hye-Seung,Chung, Doo-Hyun,Lee, Choon-Taek,Kim, Young-Hwan,Kim, Yoon-Keun,Min, Kyung-Up,Kim, You-Young,Cho, Sang-Heon The Korean Academy of Medical Sciences 2008 JOURNAL OF KOREAN MEDICAL SCIENCE Vol.23 No.3

<P>The bronchial pathology of asymptomatic airway hyperreponsiveness (AHR) subjects is not well understood, and the role of atopy in the development of airway remodeling is unclear. The aim of this study was to evaluate whether atopy is associated with airway remodeling in asymptomatic AHR subjects. Five groups, i.e., atopic or non-atopic subjects with asymptomatic AHR, atopic or non-atopic healthy controls, and subjects with mild atopic asthma, were evaluated by bronchoscopic biopsy. By electron microscopy, mean reticular basement membrane (RBM) thicknesses were 4.3±1.7 µm, 3.4±1.8 µm, 2.5±1.5 µm, 2.6±1.1 µm, and 2.3±1.2 µm in the mild atopic asthma, atopic and non-atopic asymptomatic AHR, atopic and non-atopic control groups, respectively (<I>p</I>=0.002). RBM thicknesses were significantly higher in the mild atopic asthma group and in the atopic asymptomatic AHR group than in the other three groups (<I>p</I>=0.048). No significant difference in RBM thickness was observed between the atopic asymptomatic AHR group and the mild atopic asthma group (<I>p</I>>0.05), nor between non-atopic asymptomatic AHR group and the two control groups (<I>p</I>>0.05). By light microscopy, subepithelial layer thicknesses between the groups showed the same results. These findings suggest that RBM thickening occurs in subjects with atopic asymptomatic AHR, and that atopy plays an important role in airway remodeling.</P>