• East Asian Economic Review
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• v.27 no.3
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• pp.179-211
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• 2023

This paper investigates the relationship between the spread of COVID-19 and time preference. In contrast to previous studies that compared time preferences before and during the pandemic, this study estimates time preferences during the COVID-19 period using eight surveys conducted over two years. Additionally, a regression analysis was conducted on the number of new COVID-19 cases and the time elapsed since the outbreak, with estimated time preference as the dependent variable. Despite a small sample size, statistically significant results were obtained, showing that as the number of new cases increased, time preference also increased. However, this effect diminished over time and disappeared by the end of 2021 in Japan. This may be due to the public's growing familiarity with the risks of COVID-19 and the availability of vaccines and treatments. Despite a significant increase in new cases in 2022, time preference was lower than immediately after the outbreak, and this was reflected in private investments. Immediately after the outbreak of COVID-19, private investments decreased by 12% compared to the previous year, but the investments are returning in 2022 despite the surge in the number of cases. The trend of time preference explains the trend of Japanese private investments very well.

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.4
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• pp.138-150
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• 2012

The purpose of this study was to examine the regional disparity of ambulatory health care utilization considering spatio-temporal variation in South Korea during 1996-2008(precisely, in 1996, 1999, 2002, 2005, and 2008) using bayesian hierarchial spatio-temporal model. The spatial pattern uses an intrinsic gaussian conditional autoregressive (CAR) error component. Ornstein-Uhlenbeck method was applied to detect the temporal patterns. The results showed that substantial temporal-geographical variation depending on diseases exists in Korea. On the Contrary to the pattern of total outpatient utilizations, for example, the areas that chronic diseases distributed relatively high were most in rural where the proportion of elderly population was higher than in the urban. Chungcheongnam-do, Junlabuk-do, and Kyeongsangbuk-do had higher risks in hypertension, whereas arthritis was higher risk in the Kyeonggi-do, Chungcheongbuk-do, Junlanam-do, and Junlabuk-do. The results of this study suggested that the effective health intervention programmes needed to alleviate the regional variation of health care utilization. These outcomes also provided the foundation for further investigation of risk factors and interventions in these high-risk areas.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.1
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• pp.34-43
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• 2016

Urban development and population increases are continuously progressed in the coastal areas in Korea, thus it is expected that vulnerability towards coastal disasters by sea level rise (SLR) would be accelerated. This study investigated trend of the sea level data using Mann-Kendall (MK) test, and the results showed that the increasing trends of annual average sea level at 17 locations were statistically significant. For annual maximum extremes, seven locations exhibited statistically significant trends. In this study, non-stationary frequency analysis for the annual extreme data together with average sea level data as a covariate was performed. Non-stationary frequency analysis results showed that sea level at the coastal areas of Korean Peninsula would be increased from a minimum of 60.33 mm to a maximum of 214.90 mm by 2100.

• Journal of Acupuncture Research
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• v.24 no.4
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• pp.13-23
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• 2007

Objectives : The aim of the present study was to assess the effects of Sa-am acupuncture (Damjeonggyeok) on autonomic nervous system in night nurses by heart rate variability. Methods : Five night nurses were divided into two groups. We checked their HRV once after sleeping for night and 5 times after working for night, 4 times after operation. We operate Sa-am acupuncture (Damjeonggyeok) and sham acupuncture twice by turns for group A and in reverse order for group B. We checked responses of HRV change after operations. Statistical analysis was performed by using the SPSS Win. Ver. 13.0 for analysis about correlation between data, and Baysian analysis using WinBUGS(Ver. 1.4) for comparison between Sa-am acupuncture (Damjeonggyeok) and sham acupuncture. Results : The median overall decrease for difference in responses of low-frequency power in normalized units (LF (NU)) was -16.56 (-28.88, -6.446), the median overall increase for difference in responses to high-frequency power in normalized units (HF (NU)) was 16.25 (8.104, 28.6) and for the median overall decrease for difference in responses to the ratio of low- to high-frequency power (LF/HF) was -1.846 (-3.922, -0.069), 95% credibility intervals being shown in brackets. VAS of stress was correlated with LF (NU) and HF (NU), LF/HF (p<0.0l). Conclusion : Sa-am acupuncture (Damjeonggyeok) might have sympatholytic and parasympathomimetic effects.

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2001.10a
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• pp.165-196
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• 2001

DNA chip 또는 microarray는 다수의 유전자 또는 유전자 조각을 (보통 수천내지 수만 개)칩상에 고정시켜 놓고 DNA hybridization 반응을 이용하여 유전자들의 발현 양상을 분석할 수 있는 기술이다. 이러한 high-throughput기술은 예전에는 생각하지 못했던 여러가지 분자생물학의 문제에 대한 해답을 제시해 줄 수 있을 뿐 만 아니라, 분자수준에서의 질병 진단, 신약 개발, 환경 오염 문제의 해결 등 그 응용 가능성이 무한하다. 이 기술의 실용적인 적용을 위해서는 DNA chip을 제작하기 위한 하드웨어/웻웨어 기술 외에도 이러한 데이터로부터 최대한 유용하고 새로운 지식을 창출하기 위한 bioinformatics 기술이 핵심이라고 할 수 있다. 유전자 발현 패턴을 데이터마이닝하는 문제는 크게 clustering, classification, dependency analysis로 구분할 수 있으며 이러한 기술은 통계학과인공지능 기계학습에 기반을 두고 있다. 주로 사용된 기법으로는 principal component analysis, hierarchical clustering, k-means, self-organizing maps, decision trees, multilayer perceptron neural networks, association rules 등이다. 본 세미나에서는 이러한 기본적인 기계학습 기술 외에 최근에 연구되고 있는 새로운 학습 기술로서 probabilistic graphical model (PGM)을 소개하고 이를 DNA chip 데이터 분석에 응용하는 연구를 살펴본다. PGM은 인공신경망, 그래프 이론, 확률 이론이 결합되어 형성된 기계학습 모델로서 인간 두뇌의 기억과 학습 기작에 기반을 두고 있으며 다른 기계학습 모델과의 큰 차이점 중의 하나는 generative model이라는 것이다. 즉 일단 모델이 만들어지면 이것으로부터 새로운 데이터를 생성할 수 있는 능력이 있어서, 만들어진 모델을 검증하고 이로부터 새로운 사실을 추론해 낼 수 있어 biological data mining 문제에서와 같이 새로운 지식을 발견하는 exploratory analysis에 적합하다. 또한probabilistic graphical model은 기존의 신경망 모델과는 달리 deterministic한의사결정이 아니라 확률에 기반한 soft inference를 하고 학습된 모델로부터 관련된 요인들간의 인과관계(causal relationship) 또는 상호의존관계(dependency)를 분석하기에 적합한 장점이 있다. 군체적인 PGM 모델의 예로서, Bayesian network, nonnegative matrix factorization (NMF), generative topographic mapping (GTM)의 구조와 학습 및 추론알고리즘을소개하고 이를 DNA칩 데이터 분석 평가 대회인 CAMDA-2000과 CAMDA-2001에서 사용된cancer diagnosis 문제와 gene-drug dependency analysis 문제에 적용한 결과를 살펴본다.

• Journal of Preventive Medicine and Public Health
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• v.55 no.2
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• pp.164-172
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• 2022

Objectives: We aimed to estimate the space-time distribution of the risk of suicide mortality in Iran from 2006 to 2016. Methods: In this repeated cross-sectional study, the age-standardized risk of suicide mortality from 2006 to 2016 was determined. To estimate the cumulative and temporal risk, the Besag, York, and Mollié and Bernardinelli models were used. Results: The relative risk of suicide mortality was greater than 1 in 43.0% of Iran's provinces (posterior probability >0.8; range, 0.46 to 3.93). The spatio-temporal model indicated a high risk of suicide in 36.7% of Iran's provinces. In addition, significant upward temporal trends in suicide risk were observed in the provinces of Tehran, Fars, Kermanshah, and Gilan. A significantly decreasing pattern of risk was observed for men (β, -0.013; 95% credible interval [CrI], -0.010 to -0.007), and a stable pattern of risk was observed for women (β, -0.001; 95% CrI, -0.010 to 0.007). A decreasing pattern of suicide risk was observed for those aged 15-29 years (β, -0.006; 95% CrI, -0.010 to -0.0001) and 30-49 years (β, -0.001; 95% CrI, -0.018 to -0.002). The risk was stable for those aged >50 years. Conclusions: The highest risk of suicide mortality was observed in Iran's northwestern provinces and among Kurdish women. Although a low risk of suicide mortality was observed in the provinces of Tehran, Fars, and Gilan, the risk in these provinces is increasing rapidly compared to other regions.

• Journal of Acupuncture Research
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• v.30 no.3
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• pp.39-49
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• 2013

Objectives : The purpose of this study is to assess the effect of Taegeuk acupuncture on reducing mental stress by analyzing heart rate variability in Soeumin. Methods : Six Soeumin-diagnosed men participated in this study. They were randomly divided into group A and group B. Each participant went through 4 sessions every week with 1 week of washout period in between each session. HRV was measured three times at every session; at baseline, after administering mentally stressful circumstances and after applying Soeumin Taegeuk acupuncture or Soyangin Taegeuk acupuncture. This study was designed as a crossover clinical trial. Group A participants were treated with two sets of Soeumin Taegeuk and Soyangin Taegeuk acupuncture treatment in respective order (i.e. Soeumin Taegeuk - Soyangin Taegeuk - Soeumin Taegeuk - Soyangin Taegeuk acupuncture treatment). Group B participants were treated with reverse-ordered acupuncture treatment (i.e. Soyangin Taegeuk - Soeumin Taegeuk - Soyangin Taegeuk - Soeumin Taegeuk acupuncture treatment ). Bayesian analysis was performed by using WinBUGS(Ver. 1.4.3) for comparison between Soeumin Taegeuk acupuncture and Soyangin Taegeuk acupuncture. Results : Overall, Soeumin Taegeuk acupuncture tends to reduce LF/HF ratio, LF, HF, LF(Norm) and increase HF(Norm) more than Soyangin Taegeuk acupuncture, but the difference was not statistically significant. In one participant, however, Soeumin Taegeuk acupuncture reduced LF/HF ratio, LF(Norm) and increased HF(Norm) more than Soyangin Taegeuk acupuncture, and the difference was stastatistically significant. Conclusions : This study suggests that Soeumin Taegeuk acupuncture might be an effective means of stabilizing mental stress-induced imbalance of autonomic nervous system for Soeumin.

• Journal of Energy Engineering
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• v.27 no.4
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• pp.36-49
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• 2018

This study analyzed the public preference and acceptance regarding renewable energy projects through Choice Based Conjoint Analysis. The results show that the surveyed respondents consider the leading authority of the projects, as the most important factor when considering participating in renewable energy initiatives. Following this, the mode of participation and profit distribution and the power plant location are also viewed as important, whereas participation through decision making regarding the projects was less important. Also when participating in renewable energy projects, respondents tend to prefer to financially participating through loans or owning shares rather than volunteering support for the business such as sharing information, stating one's views, or providing cooperation and coordination. Therefore, the focus is on distributional justice, such as financial investment and profit distribution, rather than procedural justice, for instance decision making. When analyzing the part-worths utilities for the participation attribute, the respondents most preferred to receiving dividends based on earnings by owning shares with the local government in charge of the entire projects. As a consequence, the results suggest that it is important to have local government get involved and have trust-worthy governing systems in place for the initiation of the public participating-renewable energy projects.

• Analyses & Alternatives
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• v.7 no.2
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• pp.35-77
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• 2023

This study aims to solve the entangled loop between demographic transition (DT) and economic growth by analyzing cross-country data. We undertake a national-level group analysis to verify the compressed transition of demographic variables over time. Assuming that the LA (latecomer advantage) on DT over time exists, we verify that the DT of the latecomer is compressed by providing a formal proof of LA on DT over income. As a DT has the double-kinked functions of income, we check them in multiple aspects: early maturation, leftward threshold, and steeper descent under a contour map and econometric methods. We find that the developing countries (the latecomer) have speedy DT (CDT, compressed DT) as well as speedy income such that DT of the latecomers starts at lower levels of income, lasts for a shorter period, and finishes at the earlier stage of economic development compared to that of developed countries (the early mover). To check the balance of DT, we classify countries into four groups of DT---balanced, slow, unilateral, and rapid transition countries. We identify that the main causes of rapid transition are due to the strong family planning programs of the government. Finally, we check the effect of latecomer's CDT on economic growth inversely: we undertake the simulation of the CDT effect on economic growth and the aging process for the latecomer. A worrying result is that the CDT of the latecomer shows a sharp upturn of the working-age population, followed by a sharp downturn in a short period. Compared to early-mover countries, the latecomer countries cannot buy more time to accommodate the workable population for the period of demographic bonus and prepare their aging societies for demographic onus. Thus, we conclude that CDT is not necessarily advantageous to developing countries. These outcomes of the latecomer's CDT can be re-interpreted as follows. Developing countries need power sources to pump up economic development, such as the following production factors: labor, physical and financial capital, and economic systems. As for labor, the properties of early maturation and leftward thresholds on DTs of the latecomer mean that demographic movement occurs at an unusually early stage of economic development; this is similar to a plane that leaks fuel before or just before take-off, with the result that it no longer flies higher or farther. What is worse, the property of steeper descent represents the falling speed of a plane so that it cannot be sustained at higher levels, and then plummets to all-time lows.

• Knowledge Management Research
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• v.25 no.2
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• pp.115-134
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• 2024

In an age where consumers can easily search and pass on their opinions of products and purchasing decisions through the internet, Electronic-word-of-mouth(Ewom) plays an important role in decision making of other potential customers. In this study, we empirically analyze the impact EWOM on consumer purchase decisions, when contradictory Ewom is presented from varying sources of information, such as experts and general consumers. First, we find that when there is a consensus among different information sources there exists a positive relationship between Ewom sentiment and purchase intent, confirming the results of previous literature. However, when expert opinion and consumer opinion do not match we find that consumer opinion is more impactful on purchasing decisions compared to the expert opinion, regardless of product types. The findings of this study add insight to the current literature by examining the effect of contradictory Ewom on purchase decisions, and also to industry marketers by presenting a more efficient strategy in promoting positive Ewom for different product types.