• 설비공학논문집
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• 제18권1호
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• pp.55-65
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• 2006

The air and water flow distribution are experimentally studied for a round header - flat tube geometry simulating a parallel flow heat exchanger. The number of branch flat tube is thirty. The effects of tube outlet direction, tube protrusion depth as well as mass flux, and quality are investigated. The flow at the header inlet is identified as annular. For the downward flow configuration, the water flow distribution is significantly affected by the tube protrusion depth. For flush-mounted configuration, most of the water flows through frontal part of the header. As the protrusion depth increases, more water is forced to the rear part of the header. The effect of mass flux or quality is qualitatively the same as that of the protrusion depth. Increase of the mass flux or quality forces the water to rear part of the header. For the upward flow configuration, however, most of the water flows through rear part of the header. The protrusion depth, mass flux, or quality does not significantly alter the flow pattern. Possible explanations are provided based on the flow visualization results. Negligible difference on the water flow distribution was observed between the parallel and the reverse flow configuration.

• 한국지역사회생활과학회지
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• 제18권4호
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• pp.539-553
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• 2007

The present study examined the effects of parent-education administered during divorce procedure on the perception of parent-education programs. The subjects were 60 couples who were in divorce procedure at the Seoul Family Court and had children under 20 Subjects were divided into three groups of 20 couples each: a control group, and experimental group 1 and experimental group 2 that were homogeneous in demographical and legal backgrounds. Experimental group 1 was shown pamphlets and videos on the role of divorced parents, and experimental group 2 was shown pamphlets and videos on the role of divorced parents as well as given explanations about the contents of the pamphlets and videos. No treatment was applied to the control group. According to the results of the experiment, the two experimental groups showed improvement in their perception of the necessity for parent-education programs. Demand for the number of sessions and hours, and the effect was higher in experimental group 2 than in experimental group 1. With regard to the necessity of parent-education programs, experimental group 2 was positive particularly to mandatory injunction, the payment of education fees and expectation of helpfulness. All three groups expected that parent-education programs would be helpful.

• Structural Engineering and Mechanics
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• 제84권5호
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• pp.605-618
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• 2022

Glass fiber reinforced polymer (GFRP) elastic gridshells consist of long continuous GFRP tubes that form elastic deformations. In this paper, a method for the form-finding of gridshell structures is presented based on the interpretable machine learning (ML) approaches. A comparative study is conducted on several ML algorithms, including support vector regression (SVR), K-nearest neighbors (KNN), decision tree (DT), random forest (RF), AdaBoost, XGBoost, category boosting (CatBoost), and light gradient boosting machine (LightGBM). A numerical example is presented using a standard double-hump gridshell considering two characteristics of deformation as objective functions. The combination of the grid search approach and k-fold cross-validation (CV) is implemented for fine-tuning the parameters of ML models. The results of the comparative study indicate that the LightGBM model presents the highest prediction accuracy. Finally, interpretable ML approaches, including Shapely additive explanations (SHAP), partial dependence plot (PDP), and accumulated local effects (ALE), are applied to explain the predictions of the ML model since it is essential to understand the effect of various values of input parameters on objective functions. As a result of interpretability approaches, an optimum gridshell structure is obtained and new opportunities are verified for form-finding investigation of GFRP elastic gridshells during lifting construction.

• Human Ecology Research
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• 제55권3호
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• pp.275-287
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• 2017

The recent Great Recession of 2008 was a period of sharp economic decline throughout the late 2000s. All socio-demographic groups were impacted by the economic downturn, however, Hispanic households were particularly hard hit. It is not a recent phenomenon that minority groups often have greater problems related to credit and debt repayments. A better understanding of these racial/ethnic differences in credit and debt has been hindered by the propensity of many studies to pool all racial/ethnic minorities together and compare them to white households. Using a Heckman-type selection model with a combination of the 2010 and 2013 Survey of Consumer Finances datasets to study household debt repayment problems, we found that racial/ethnic groups have been differently impacted by the recent Great Recession in terms of debt repayment problems. Hispanic households were less likely to hold debt; however, those with debt were just as likely as white households and African American households to be delinquent in repayments. This finding is contrary to prior research that indicated Hispanics with debt were less likely than white and African American households to be delinquent on repayments prior to the Great Recession of 2008. We propose possible explanations for the increase in debt repayment problems, that includes increased assimilation into the U.S. culture of credit use, the circumstance of being more recent home buyers prior to the decline, and living in states that suffered the greatest decline in housing value.

• The Journal of Asian Finance, Economics and Business
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• 제9권2호
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• pp.363-370
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• 2022

The study aims to probe the impact of foreign ownership on Vietnamese listed firms' capital structure. This study employs panel data of 288 non-financial firms listed on the Ho Chi Minh City stock exchange (HOSE) and Ha Noi stock exchange (HNX) in 2015-2019. In this research, we applied a Bayesian linear regression method to provide probabilistic explanations of the model uncertainty and effect of foreign ownership on the capital structure of non-financial listed enterprises in Vietnam. The findings of experimental analysis by Bayesian linear regression method through Markov chain Monte Carlo (MCMC) technique combined with Gibbs sampler suggest that foreign ownership has substantial adverse effects on the firms' capital structure. Our findings also indicate that a firm's size, age, and growth opportunities all have a strong positive and significant effect on its debt ratio. We found that the firms' profitability, tangible assets, and liquidity negatively and strongly affect firms' capital structure. Meanwhile, there is a low negative impact of dividends and inflation on the debt ratio. This research has ramifications for business managers since it improves a company's financial resources by developing a strong capital structure and considering foreign investment as a source of funding.

• Childhood Kidney Diseases
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• 제16권1호
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• pp.9-14
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• 2012

The relationship between central nervous system (CNS) and enuresis has not been sufficiently elucidated despite the presence of several circumstantial evidences. Contrary to common belief, polysomnographic sleep analysis revealed that the disturbance of arousal rather than deep sleep was responsible for enuresis. Subsequent studies confirmed depressed sympathetic tone and retarded brainstem reflex indicating abnormal arousal threshold in enuretics. In accordance with the bladder-brain dialogue, chronic stimulation of bladder may modify the brainstem function elevating arousal threshold. Epidemiological studies have suggested the association between enuresis and various psychosomatic disorders like attention deficit hyperactivity disorder (ADHD), which has shown the abnormal brainstem reflex similar to enuresis. Taken together, CNS is assumed to play a crucial role in the pathogenesis of enuresis. Psychological assessment is vital to understand the psychodynamic effect of enuresis. Studies have shown that the prevalence of psychological problems was higher in enuretic children and externalization of the symptoms was usually found. Several explanations have been brought up regarding the development of enuresis and psychological problems. Enuresis may cause psychological problems and vice versa. Otherwise, both may be associated with other variables, such as socioeconomic status (SES).

• 천문학회지
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• 제46권6호
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• pp.235-242
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• 2013

We compare mass-loss rates of OH/IR stars obtained from radio observations with those derived from the dust radiative transfer models and IR observations. We collect radio observational data of OH maser and CO line emission sources for a sample of 1533 OH/IR stars listed in Suh & Kwon (2011). For 1259 OH maser, 76 CO(J=1-0), and 55 CO(J=2-1) emission sources, we compile data of the expansion velocity and mass-loss rate. We use a dust radiative transfer model for the dust shell to calculate the mass-loss rate as well as the IR color indices. The observed mass-loss rates are in the range predicted by the theoretical dust shell models corresponding to $\dot{M}=10^{-8}M_{\odot}/yr-10^{-4}M_{\odot}/yr$. We find that the dust model using a simple mixture of amorphous silicate and amorphous $Al_2O_3$ (20% by mass) grains can explain the observations fairly well. The results indicate that the dust radiative transfer models for IR observations generally agree with the radio observations. For high mass-loss rate OH/IR stars, the mass-loss rates obtained from radio observations are underestimated compared to the mass-loss rates derived from the dust shell models. This could be because photon momentum transfer to the gas shell is not possible for the physical condition of high mass-loss rates. Alternative explanations could be the effects of different dust-to-gas ratios and/or a superwind.

• Journal of Contemporary Eastern Asia
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• 제13권2호
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• pp.15-39
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• 2014

This research conducted a before/after naturalistic field experiment, with the early Arab Spring as the treatment. Compared to before the early Arab Spring, after the observation period the associations became stronger among the Web terms: 'Jihad, Sharia, innovation, democracy and civil society.' The Western concept of civil society transformed into a central Islamist ideological component. At another level, the inter-nation network based on Jihad-weighted Web hyperlinks between pairs of 46 Muslim Majority (MM) nations found Iran in one of the top two positions of flow betweenness centrality, a measure of network power, both before and after early Arab Spring. In contrast, Somalia, UAE, Egypt, Libya, and Sudan increased most in network flow betweenness centrality. The MM 'Jihad'-centric word co-occurrence network more than tripled in size, and the semantic structure more became entropic. This media "cloud" perhaps billowed as Islamist groups changed their material-level relationships and the corresponding media representations of Jihad among them changed after early Arab Spring. Future research could investigate various rival explanations for this naturalistic field experiment's findings.

• 만화애니메이션 연구
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• 통권11호
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• pp.87-104
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• 2007

본 논문에서는 중국 수묵애니메이션의 예술적 특징, 특히 중국애니메이션에 있어서 일 세대 감독인 특위의 <피리부는 목동>에 나타난 선적(線的) 표현을 중심으로 분석하였다. 본 작품의 연구에 앞서 선의 개념과 이해 그리고 조형적인 특성에 관한 이론적 설명과 더불어 중국애니메이션의 발전과 그 원동력인 상해애니메이션 필름스튜디오의 작품을 통해 수묵애니메이션의 변천을 살펴보았다. 아울러 본 논문의 중심인 <피리부는 목동>의 선의 표현 및 심미성과 사상성 등을 고찰하고 수묵과 선의 작용 및 애니메이션과의 관계를 통해 예술적 가능성을 알아보았다.

• 한국언론정보학보
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• 제48권
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• pp.191-210
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• 2009

본 연구에서는 뉴스 메시지의 프레임과 개인의 관여도가 과학기술 관련 위험인식에 미치는 영향을 알아보고자 하였다. 이를 위해 위험에 대한 낙관적 편견과 제3자 효과 이론을 이론적 근거로 하여 가설을 제시하고 실험을 통해 검증하고자 하였다. 실험에서는 피험자를 방사선 조사식품에 대한 고관여자와 저관여자 집단으로 구분하고 뉴스 메시지의 프레임에 따라 이들이 자신과 다른 사람들에 대한 위험인식 과정에서 어떠한 특징을 보이는가를 조사하였다. 연구결과, 부정프레임 기사를 접한 저관여자를 제외하면 실험조건 별 사회수준 위험인식은 상대적으로 유사한 것으로 나타났다. 반면 개인수준의 위험인식은 기사 프레임과 관여도에 따라 다르게 형성되었다. 본 연구에서는 이러한 두 수준의 위험인식을 실험조건 별로 비교하여 낙관적 편견이 나타나는 과정에 대한 이해를 시도하였다.