• 한국대기환경학회지
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• 제21권3호
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• pp.377-397
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• 2005

A new box model is proposed to describe the dynamic trend of the spatially averaged concentrations of pollutants over a large urban area such as metropolitan Seoul. Being averaged temporally and spatially over a thresh-hold scales, the dynamics of the pollutant concentration becomes simple enough that the governing equation can be expressed in an explicit algebraic form as a function of several meteorological factors and the pollutant emission rate. The single most important meteorological factor is the wind speed dominating the daily variations of the pollutant concentrations. Given the meteorological data from the surface station in the metropolitan Seoul, the model concentration shows excellent agreement with observations from January 1, 1990 to December 31, 2000: the modeling uncertainty, for example, of $NO_2$ concentrations, defined as mean differences between the model concentrations and observations is $16\%$ of the model concentrations. Even for $PM_{10}$ of which secondary sources are considered to be very important and simple box model is irrelevant to, the model performance turns out good, modeling uncertainty being about $32\%$.

• 한국대기환경학회지
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• 제27권6호
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• pp.751-771
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• 2011

Biogenic Volatile Organic Compound (BVOC) emissions are estimated with BEIS3.12 (Biogenic Emissions Inventory System version 3.12) over the Seoul Metropolitan Area (SMA) and then used in CMAQ (Community Multiscale Air Quality) simulations for two high ozone episodes in 2004 and 2007 June. The first- and second-order sensitivity coefficients of ozone to BVOC emissions are estimated with High-order Decoupled Direct Method (HDDM) simulation in order to estimate the influence of BVOC emissions on ozone using the Zero-Out Contribution (ZOC) approach. ZOC analysis shows that relative contribution of BVOC emissions on daily maximum 1-hr ozone is as high as 30% for high ozone days above 100 ppb. However simulated isoprene concentrations were over-estimated by a factor of 2 when compared to the observations at the PAMS (Photochemical Air Monitoring Station) for the 2007 episode. When assumed that actual BVOC emissions are 50% less than estimated, the ZOC of BVOC emissions on daily maximum ozone drops by more than 10 ppb for the episode. The result indicates that uncertainty in BVOC emissions may have significant impact on high ozone prediction in the SMA.

• 한국대기환경학회지
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• 제18권6호
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• pp.465-474
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• 2002

In order to reflect variability due to exposure factors as well as to assess uncertainty associated with cancer risk posed by airborne trace metals, a Monte Calro analysis has been made in this study. Input parameters for Monte Carlo analysis were developed or adjusted using body weight, lifetime, and exposure frequency of Koreans. Ambient distributions of toxic metals were founded to be lognormal distributions for most of them using goodness-of-fit tests. Thus, the 95% UCL and 95% LCL of carcinogenic metals were estimated by H-statistic method for lognormal distribution, respectively. The results of Monte Carlo analysis of 95% UCL showed that the 95th percentile risks for men and women were 1.2 and 1.1 times higher than an acceptable risk of 10$^{-5}$ , respectively. The probabilities which those risks exceed the acceptable risk were estimated to be 8% and 6%, respectively, while to be 95% and 94%, respectively on the basis of the minimum acceptable risk of 10$^{-6}$ , respectively. Approximately 90% of total cancer risk came from human carcinogens such as arsenic and hexavalent chromium. Therefore, it is necessary to properly manage both arsenic and hexavalent chromium emissions in the study area.

• The Journal of Asian Finance, Economics and Business
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• 제8권2호
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• pp.151-164
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• 2021

The paper identifies the enablers (drivers) and inhibitors (barriers) influencing e-customs implementation in Vietnam (known as a developing country with a lower technological environment) along with determining the impact of e-customs on firm performance. The survey was conducted with the representatives (managers) of firms in five cities and provinces dominating Vietnam's international trade. The data was analyzed using structural equation modeling (SEM). The findings show two significant drivers (enablers) - relative advantages and national culture, while compatibility and ease of use are the barriers. Previous studies showed that cultural dimensions related to 'uncertainty acceptance' and 'individualism' encourage innovation; however, this paper demonstrates that 'uncertainty avoidance' and 'collectivism' promote e-customs deployment in Vietnam. Previously, Vietnamese culture was known for scoring high on cultural dimensions related to 'power distance' and 'short-term orientation'. However, today, as an emerging country, Vietnamese has switched to 'low distance' and 'long-term orientation', especially in terms of e-customs innovation. Additionally, the paper also emphasized that e-customs implementation had a positive influence on firm performance in Vietnam. Based on the results of the paper, policy-makers can devise essential solutions to enhance e-customs implementation as well as managers of firms can set-up strategies to adapt to the modernized environment.

• 통상정보연구
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• 제16권1호
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• pp.163-183
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• 2014

본 연구는 수요부문 환경의 불확실성이 제조업체의 유통업체에 대한 의존성, 결속과 전략적 성과에 어떻게 영향을 주는지를 한국과 미국의 제조업체를 통해 검증해 보았다. 이러한 연구는 수요부문 환경의 불확실성에 대해서 한국의 제조업체와 유통업체만을 연구한 것이 아니라, 미국의 표본까지 확보하여 유통환경이 다른 국가를 비교 연구하였다는 것에 커다란 의의가 있다고 할 수 있다. 설문은 유통업체와 직접 접촉이 있는 제조업체를 대상으로 수집하였고, 한국기업 105개, 미국기업 103개의 데이터를 가지고 구조방정식으로 분석을 하였다. 결과는 다음과 같다. 수요부문 환경의 불확실성이 높을수록 의존성이 높을 것이라는 가설 1은 한국과 미국에서 모두 채택되었다. 수요부문 환경불확실성이 높을수록 결속이 높을 것이라는 가설 2는 한국에서는 기각되었고, 미국에서는 채택되었다. 수요부문 환경의 불확실성이 높을수록 전략적 성과가 높을 것이라는 가설 3은 한국, 미국 두 국가 모두에서 기각되었다. 의존성이 높을수록 전략적 성과가 높을 것이라는 가설 4는 한국에서는 채택되었고, 미국에서는 기각되었다. 결속이 높을수록 전략적 성과가 높을 것이라는 가설 5는 한국, 미국 모두에서 채택되었다. 향후 연구에서는 제조업체와 유통업체의 의존성과 결속, 전략적 성과를 측정함에 있어서 상호관점에서 측정할 필요가 있을 것이다. 또한 향후 추가자료를 확보하여 표본을 늘릴 필요가 있을 것이다. 그리고 환경 불확실성이 수요부문 환경의 불확실성뿐만 아니라 유통환경의 모든 불확실성이 같은 차원에서 비교 연구될 필요가 있을 것이다.

• Asian Journal of Innovation and Policy
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• 제4권3호
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• pp.328-359
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• 2015

To explain the performance gap between firms in the same industry, this study focuses on innovation. It provides a new framework using the dynamic-capability view based on empirical analysis of domestic businesses. The findings of this study are as follows: First, when the uncertainty and competition intensity in the business environment and the level of innovation have “fit”, it means that when the former goes up, so does the latter. In this regard, when the innovation capability of a firm is high, being “fit” means that the level of innovation is also high. When there was fitting innovation on industrial environment and innovation capacity, companies were able to achieve relatively high performance. Also, it was confirmed that instead of innovation for innovation capacity, innovation for industrial environment led to relatively higher performances of firms.

• 한국관광식음료학회지:관광식음료경영연구
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• 제14권1호
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• pp.1-19
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• 2003

Organizations should constantly modify and refine the mechanism by which they achieve their purposes- no only by scanning the environmental change and uncertainty, but also by choosing the right strategies. As scanning largely perceived environment, the management need to maintain a systemized perspective on their environment in order to make profitable decisions(strategic choice). Accordingly, this article presents a theoretical framework that top managers or managers of food service organizations can use to analyze their environment as an integrated and systemized whole - a model that take into account the interrelationships among domains of environment and strategic choice. Also, the results of this study will be a guideline for further expanded environmental scanning.

• 한국초등과학교육학회지:초등과학교육
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• 제32권2호
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• pp.198-205
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• 2013

For assessing classroom environment, numerous instruments were developed and reported the survey results for science students in science education. In this study I translated Constructivist Learning Environment Scales (CLES) were into Korean versions for elementary school teachers, and measured the reliability. The subjects were randomly selected from three departments of an University of Education in a metropolitan city. All of them were 110 students, who would be elementary school teachers. According to the survey results, pre-service teachers for elementary school have recognized constructivistly for learning environments in an actual forms. In a scale of student negotiation they have most constructivistly recognized learning environment, and moderately in scales of relevance, uncertainty and critical view while they have seldom constructivistly recognized in a scale of shared control. Also Korean version CLES would be an reliable instruments for constructivist assessing learning environments.

• 한국시뮬레이션학회논문지
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• 제28권4호
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• pp.21-32
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• 2019

군집에 대한 사회적 행동 모델에 영감을 받은 군집 최적화 알고리즘은 복잡한 최적화 문제 해결에서부터 인공 신경망의 학습에까지 활용되는 대표적인 메타휴리스틱 최적화 알고리즘 중의 하나이다. 하지만 이 알고리즘은 기본적으로 확률적 노이즈가 존재하지 않는 결정적인 환경에서 개발되었기 때문에, 많은 경우 확률적 노이즈가 존재하는 실제 문제에 적용하기에 어려움이 있었다. 본 논문에서는 이를 개선하기 위하여 불확실 평가 기법이라고 정의되는 통계적 가설 검정 기반의 리샘플링 기법을 적용한다. 이 기법을 통하여 입자 군집 최적화 알고리즘의 성능에 가장 큰 영향을 미치는 입자들의 전역 최적을 정확하게 찾으므로 노이즈 환경에서 입자들이 최적해로 보다 정확하고 빠르게 수렴하도록 한다. 다양한 벤치마크 문제들에 대한 기존 알고리즘들과의 비교 실험 결과는 제안하는 알고리즘의 개선된 성능을 입증하고, 사례 연구의 결과는 본 연구의 필요성을 강조한다. 본 연구 결과가 4차 산업혁명 시대에 디지털 트윈 등을 통한 시뮬레이션 기반 시스템 최적화에 효과적으로 적용될 수 있을 것이라 기대한다.

• 신재생에너지
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• 제16권1호
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• pp.1-14
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• 2020

Liquid air energy storage (LAES) using gas liquefaction has attracted considerable attention because of its mature technology, high energy density, few geographical constraints, and long life span. On the other hand, LAES has not yet been commercialized and is being developed recently. Therefore, few studies have performed an economic analysis of LAES. In this study, the levelized cost of electricity was calculated and compared with that of other energy storage systems. As a result, the levelized cost of electricity of LAES was $371/MWh. This is approximately $292/MWh, $159/MWh, $118/MWh, and $3/MWh less than that of the LiCd battery, VRFB battery, Lead-acid battery, and NaS battery. In addition, the cost was approximately $62/MWh and $195/MWh more than that of Fe-Cr flow battery and PHS. Sensitivity analysis of the levelized cost of electricity according to the main economic factors was performed, and economic uncertainty analysis was performed through a Monte-Carlo simulation. The cumulative probability curve showed the levelized cost of electricity of LAES, reflecting price fluctuations in the air compressor cost, electricity cost, and standing reserve hourly fee.