• 응용통계연구
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• 제19권1호
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• pp.33-41
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• 2006

최근 들어 시계열 자료 분석에서 관측된 각 시점에서의 관측치의 분산을 서로 다른 분산(조건부 이분산성)을 따른다고 가정하고, 이를 분석하는 모형(ARCH, GARCH, EGARCH, IGARCH 등)들이 옵션 가격 분석이나 환율 변화 등 경제적 시계열 자료의 예측 모형을 위하여 활발히 연구되고 있다. 본 논문에서는 한국의 KOSPI 데이터 (1999년 1월 4일 $\sim$ 2003년 12월 30일, 총 1227일)를 바탕으로 조건부 우도함수 모수 추정 방법을 이용한 GARCH(1,1), IGARCH(1,1), EGARCH(1,1) 모형에 KOSPI 자료를 적합 시켜 각 모형들의 성능을 비교하여 보았다.

• 대한조선학회논문집
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• 제36권1호
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• pp.99-108
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• 1999

초고층강제어초(VEry High-rise Steel Artificial Reef, VEHSAR)의 형상 표현과 해석을 위해서 3차원 모델링 프로그램을 Windows 95(또는 Windows NT) 환경하에서 MFC(Microsoft Foundation Class)를 기반으로 한 Visual C++로 개발하였다. 컴퓨터를 통해 미리 초고층 강제어초 건조를 실제와 같이 구현해 봄으로써 문제점의 사전 예측 및 대책 수립 등을 가능케 하는 저비용 고효율의 일관설계시스템을 구축하는 것을 목표로 하는 이 프로그램은 객체지향프로그램 기법과 CAD/CAM기술의 도입으로 생산성 향상이 기대되며, OpenGL이라는 그래픽 라이브러리를 도입하여 좀더 빠른 고화질의 3차원 그래픽을 화면상에 나타나게 할 수 있다.

• 한국지리정보학회지
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• 제4권2호
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• pp.46-60
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• 2001

본 논문은 객체분산 시스템인 Web GIS시스템를 구축하고 UML을 이용하여 가시화, 시스템 구조와 행동을 명세화하였다. GIS의 UML 개념모델의 연구는 Shapefile를 모델개념으로 클래스도와 스테레오타입으로 추상화하였다. 통합된 모델인 UML을 사용하여 아키텍처와 역공 학을 중심으로 모델링하였다. 본 연구는 시스템을 구축하고 기본 형태를 제공하며, 시스템 분석/설계의 문서화를 통하여 S/W시스템의 기본 요소를 객체 또는 클래스로 파악하여 문제 영역과 해결 영역을 모델링함으로써 요구사항 변화시 적응력을 높이고 대규모 시스템에서 유지 보수들을 포함한 관리를 보다 능동적으로 관리할 수 있음을 제시할 수 있었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.236-239
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• 2011

This paper introduces the design concepts and characteristics of WinDS3000$^{TM}$(TC IIa) which is a trade name of Doosan's 3MW offshore/onshore wind turbine. WinDS3000$^{TM}$(TC IIa) has been designed in consideration of high Reliability, Availability, Maintainability and Serviceability (RAMS) and low cost of electricity (CDE) for the TC IIa condition based on GL guideline. An integrated drive-train design with an innovative three-stage gearbox has been introduced to minimize nacelle weight of the wind turbine and to enhance a high reliability for transmission. A permanent magnet generator with full converter system has been introduced to get higher efficiency in partial load operation and grid-friendly system for both 50 Hz and 60 Hz. A pitch-regulated variable speed control system has been introduced to control wind turbine power while generator reaction torque can be adjusted almost instantaneously by the associated power electronics. The wind turbine has been also equipped with condition monitoring and diagnostic systems in order to meet maintainability requirements.

• 대기
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• 제27권1호
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• pp.17-28
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• 2017

The sensitivity of the typhoon track and intensity simulation to physics schemes of the global model are examined for the typhoon Bolaven and Tembin cases by using the Global/Regional Integrated Model System-Global Model Program (GRIMs-GMP) with the physics package version 2.0 of the Korea Institute of Atmospheric Prediction Systems. Microphysics, Cloudiness, and Planetary boundary Layer (PBL) parameterizations are changed and the impact of each scheme change to typhoon simulation is compared with the control simulation and observation. It is found that change of microphysics scheme from WRF Single-Moment 5-class (WSM5) to 1-class (WSM1) affects to the typhoon simulation significantly, showing the intensified typhoon activity and increased precipitation amount, while the effect of the prognostic cloudiness and PBL enhanced mixing scheme is not noticeable. It appears that WSM1 simulates relatively unstable and drier atmospheric structure than WSM5, which is induced by the latent heat change and the associated radiative effect due to not considering ice cloud. And WSM1 results the enhanced typhoon intensity and heavy rainfall simulation. It suggests that the microphysics is important to improve the capability for typhoon simulation of a global model and to increase the predictability of medium range forecast.

• Spatial Information Research
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• 제5권2호
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• pp.177-183
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• 1997

토지이용 분류 체계상에서의 종류라는 개념은 토지이용 변화의 분류 체계성에 그대로 적용시킬 수가 있다. 본 연구에서는 선형 판별 함수를 원용하는 최우법(Maximum likelihood method)으로 산출되는 토지이용분류의 공간적 결과와 Markov 전이 행렬 방법으로 산출되는 정량적 결과가 상호 보완하는 의미에서 합성모형으로 통합되었다. 본 연구에서는 다변수 판별 함수의 계산법과 Markov 연쇄행렬 계산법에 관하여 토의되고 그 합성 모형을 대상 지역에 실제 적용하여 그 결과 '90년, '95년 토지이용도가 예측 작성되었다. 모형화의 문제 및 예측의 정확도 역시 더욱 토의 되어야 하며 추후 개선의 여지를 남긴다.

• 한국초등과학교육학회지:초등과학교육
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• 제38권4호
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• pp.496-509
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• 2019

This study explores the types of epistemic emotions that elementary-school students experience in science classes and the cognitive appraisal factors that affect these emotions. Thirty-two fourth-grade students of an elementary school in Gyeonggi-do, South Korea, participated in 20 science periods and wrote emotional diaries at the end of each class. In addition, the researcher conducted follow-up interviews to investigate the types of cognitive appraisal factors that caused the students to experience specific epistemic emotions that were recorded in their emotional diaries. The emotional diaries and interview data were analyzed using the constant comparative method of qualitative analysis. As a result, it was found that students experienced various positive and negative epistemic emotions. In addition, the cognitive appraisal factors experienced by the students were categorized into curriculum knowledge, experimental materials, experimental content, students, teachers, themselves, and integrated factors. We discussed that students' epistemic emotions are constructed cognitively and socially and that students inevitably experience negative epistemic emotions during science classes.

• 한국학교ㆍ지역보건교육학회지
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• 제4권
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• pp.157-169
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• 2003

This research was intended to have a grasp of the problems in physical education curriculum, After making an alternative plans of effective management. those were integrated and analyzed their own relations on the purpose of suggesting alternative plans to foster professionality of physical education teacher in order to improve real class of physical education. For this purpose, I referred to sundry records related with instruction of physical education teacher and also conducted a survey with 10 interviews such as researchers of central government education administration, and school commissioners in the ministry's provincial offices of education, professors in the university of pre-teacher training, and teachers involved in physical education. The conclusions were as follows; Physical education curriculum should be organized to reduce and diversify of the sport contents in various levels. Also, it should instruct students based on physical educational knowledge, and it is made up to know the achievement of goals through evaluation tools and development of rules having propriety and reliability. Such a physical educational curriculum developed from real class should inform continuously throughout the Ministry of Education & Human Resources Development and educational organization of physical education teachers and network of the school and mass media. So, it makes most people's recognition raise up, and we need discretionary authority of physical education teacher about time allocation of 45 minutes or 50 minutes for variety of lessons. And we need systematic installation such as reorganization of completion field in level of school.

• 전력전자학회논문지
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• 제24권1호
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• pp.40-48
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• 2019

Hybrid electric propulsion systems (H-EPSs) are an intermediate step for integrated full electric propulsion warships. H-EPSs are a dynamic combination of mechanical and electrical propulsion systems to achieve the required mission performances. The system modes could adapt to meet the requirement of the various operation conditions of a warship. This paper presents a configuration and operating modes of H-EPSs considering the operation conditions of a destroyer class warship. The system has three propulsion modes, namely, motoring mode, generating mode [power take off (PTO) mode], and mechanical mode. The PTO mode requires a careful fuel efficiency analysis because the fuel consumption rate of propulsion engines may be low compared with the generator's engines depending on the loading power. Therefore, the calculation of fuel consumption according to the operating modes is performed in this study. Although the economics of the PTO mode depends on system cases, it has an advantage in that it ensures the reliability of electric power in case of blackout or minimum generator operation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권2호
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• pp.632-657
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• 2022

Detecting web attacks is a major challenge, and it is observed that the use of simple models leads to low sensitivity or high false positive problems. In this study, we aim to develop a robust two-stage deep learning based stacked ensemble web application firewall. Normal and abnormal classification is carried out in the first stage of the proposed WAF model. The classification process of the types of abnormal traffics is postponed to the second stage and carried out using an integrated stacked ensemble model. By this way, clients' requests can be served without time delay, and attack types can be detected with high sensitivity. In addition to the high accuracy of the proposed model, by using the statistical similarity and diversity analyses in the study, high generalization for the ensemble model is achieved. Within the study, a comprehensive, up-to-date, and robust multi-class web anomaly dataset named GAZI-HTTP is created in accordance with the real-world situations. The performance of the proposed WAF model is compared to state-of-the-art deep learning models and previous studies using the benchmark dataset. The proposed two-stage model achieved multi-class detection rates of 97.43% and 94.77% for GAZI-HTTP and ECML-PKDD, respectively.