미계측유역의 수문모형 매개변수 추정을 위한 하이브리드 지역화모형의 개발

김영일,서승범,김영오,Kim, Youngil,Seo, Seung Beom,Kim, Young-Oh 한국수자원학회 2018 한국수자원학회논문집 Vol.51 No.8

There remain numerous ungauged watersheds in Korea owing to limited spatial and temporal streamflow data with which to estimate hydrological model parameters. To deal with this problem, various regionalization approaches have been proposed over the last several decades. However, the results of the regionalization models differ according to climatic conditions and regional physical characteristics, and the results of the regionalization models in previous studies are generally inconclusive. Thus, to improve the performance of the regionalization methods, this study attaches hydrological model parameters obtained using a spatial proximity model to the explanatory variables of a regional regression model and defines it as a hybrid regionalization model (hybrid model). The performance results of the hybrid model are compared with those of existing methods for 37 test watersheds in South Korea. The GR4J model parameters in the gauged watersheds are estimated using a shuffled complex evolution algorithm. The variation inflation factor is used to consider the multicollinearity of watershed characteristics, and then stepwise regression is performed to select the optimum explanatory variables for the regression model. Analysis of the results reveals that the highest modeling accuracy is achieved using the hybrid model on RMSE overall the test watersheds. Consequently, it can be concluded that the hybrid model can be used as an alternative approach for modeling ungauged watersheds.

스마트시티 에너지 감시를 위한 CIM(Common Information Model) 프로파일 설계

김영일,채창훈,김예리,이지훈,Youngil, Kim,Changhun, Chae,Yeri, Kim,Jihoon, Lee 한국전력공사 2022 KEPCO Journal on electric power and energy Vol.8 No.2

With the advent of high technologies such as the 4th Industrial Revolution and artificial intelligence and big data, efforts are being made to solve urban problems and improve the quality of life by applying new technologies in the smart city field. In addition, as carbon neutrality has emerged as an important issue due to global warming, smart city energy platform technologies such as urban energy management, efficiency improvement, and carbon reduction are in the spotlight. In order to effectively manage urban energy, energy resource information such as electricity, water, gas, hot water, heating, etc. must be collected from the management system of various energy utilities and managed on the central platform. The centrally integrated data is delivered to external city management systems that require city energy information through an energy platform. This study developed a CIM profile for smart city energy monitoring required to provide energy data to external systems. Electric data model were designed using the CIM class of IEC 61970, and water, gas, and heat data model were designed in compliance with the UML-based design ideas of IEC 61970.

다중 외삽점에서의 최적 실험설계법을 위한 실험설계기준

김영일,장대흥,Kim, YoungIl,Jang, Dae-Heung 한국통계학회 2014 응용통계연구 Vol.27 No.5

When setting up an experiment for extrapolation at multiple points outside the design space, we often face a difficulty in which point we should emphasize even if the polynomial model under consideration is given. In this paper we propose various methods under two possible scenarios that deal with extrapolations. One considered in this paper is the situation when the model assumed can be extended beyond the design space. In this setting, the many classical methods(including various approaches the authors proposed before) were revisited in the context of extrapolation. But the real problem arises when there is an uncertainty concerning the validity of the assumed model. Therefore, the second scenario is to develop an appropriate procedure when we have limited information about model. Consequently, a hybrid approach is suggested to deal with this issue of how to handle the multiple extrapolating under model uncertainty. A search algorithm was implemented because the classical exchange algorithm was found difficult to handle the complexity of the problem.

다양한 형상의 동일 기종 항공기에 대한 성능개량 최적 구현 방안 연구

김영일,안승범,최명석,Kim, Youngil,Ahn, Seungbeom,Choi, Myeongseok 한국군사과학기술학회 2022 한국군사과학기술학회지 Vol.25 No.3

In this paper, we studied the optimal method of improving performance for aircraft having various variants within the same type. The study defined configuration of an entire fleet of aircraft being subject to a performance improvement program. And selected the most complicated aircraft configuration among them as a Standard Aircraft for modification by according to the proposed Aircraft Selection Process for developing an optimal Aircraft Performance Improvement Process. Based on the selected the Standard Aircraft, drew a system integration design result and carried out Evaluation Test and obtained Airworthiness Certification. Created the database with the design data of the Standard Aircraft, Evaluation Test, and Airworthiness Certification results, and applied it to variants of aircraft to complete the performance improvement program with optimized schedules and costs. By applying the proposed method to IFF performance improvement program, drew optimal system integration design and completed the program with minimized schedule.

비선형모형에 적용한 제약조건 최적실험의 예제들

김영일,장대흥,이성백,Kim, Youngil,Jang, Dae-Heung,Yi, Seongbaek 한국통계학회 2014 응용통계연구 Vol.27 No.7

비선형모형에 대한 최적실험은 주어지는 모수의 초기값에 의존하는 특징이 있음에도 불구하고 비선형모형에 대한 최적실험은 비선형모형이 주류인 생물이나 화학공학 통계분야에서는 끊임없이 연구되어 왔다. 본 연구에서는 실험자가 다수의 실험목적을 가지고 있는 환경에서 상충되는 목적간의 균형을 맞추는 관점에서 비선형 모형에 대한 최적실험 기준을 제약 실험으로 살펴보았다. 문헌에서 존재하는 기존의 방법 뿐 아니라 새로운 융합기준도 적용하였는데 시나리오 별로 그 적용 형태를 몇 가지 비선형 모형을 통하여 알아보았다.

빔포밍 및 DOA 기반의 마스킹을 이용한 2채널 잡음제거

김영일,정상배,Kim, Youngil,Jeong, Sangbae 한국정보통신학회 2013 한국정보통신학회논문지 Vol.17 No.1

In this paper, we propose a multi-channel speech enhancement algorithm using beamforming and direction-of-arrival (DOA)-based masking. The proposed algorithm enhances noisy speech basically by the linearly constrained minimum variance (LCMV) algorithm and then a mel-scale Wiener filter designed using DOA-based masking is applied to remove still remaining noises. To improve the performance, we optimize the learning rate of the adaptive filters in LCMV and the DOA threshold to detect target speech spectrum. As performance indices, the perceptual evaluation of speech quality (PESQ) score and output SNRs are measured. Experimantal results show that the proposed algorithm outperforms the conventional LCMV beamformer by 0.09 in PESQ score and 5.75 dB in output SNR, respectively.

냉매의 특성인자 예측

김영일(Youngil Kim) 대한설비공학회 1997 대한설비공학회 학술발표대회논문집 Vol.1997 No.6-1

스티븐스 시에 나타난 최상의 허구를 위한 통합

김영일(Kim, Youngil) 한국외국어대학교 영미연구소 2013 영미연구 Vol.29 No.-

This paper aims to explore the unity of two opposite things in a poem, "Notes toward a Supreme Fiction." Stevens presents three propositions to fulfill the Supreme Fiction. They are "It Must be Abstract," "It Must Change," and "It Must Give Pleasure." There are some significant elements for the supreme fiction. In "It Must be Abstract", "Abstract," "first idea," and "major man" are important ideas for the supreme fiction. The first step, Stevens argues, for the supreme fiction is, the poet should annihilate all existing fictions. The abstract does not exist, but it is certainly immanent. That is to say, the fictive abstract is immanent in the mind of the poet. "First idea" is obtained only by those who have a fictive abstract. "Major man" who has first idea and abstract is essential to complete the supreme fiction. In "It Must Change," change is the process of becoming and it is part of the act of imagination, by which we can perceive the world and reality. In "It Must Give Pleasure," Stevens believes that men have a strong desire to know everything and they name things for the purpose of their desire. Their naming is fiction, for they are not the things themselves. But Stevens knows that to fulfill the desire for knowledge is impossible and he cherishes the fluid moments when we create poems. This study aiming on some aspects of unity of "Notes toward a Supreme Fiction" shows another perspective of his major concerns. His poetry plays a great role in giving man and the world truth as a belief and pleasure in life. Even though the supreme fiction cannot be reached, the effort to fulfill it is so cherishable that it is always toward our spirits and bodies.

석탄회를 활용한 CLSM의 pH 저감에 관한 연구

김영일(Kim Youngil),지성현(Jee Sunghyun),천병식(Chun Byungsik) 한국지반환경공학회 2010 한국지반환경공학회논문집 Vol.11 No.9

CLSM은 다짐이 필요없고 유동성이 큰 물질로 일반적으로 시멘트, 잔골재, 물, 혼화재 등을 혼합하여 만들어진다. 기존의 저강도고유동화재는 잔골재로 모래를 사용하고 있으나 모래를 구하기 점점 어려워지는 현 시점에서 저강도고유동화재를 대량으로 활용하기 위해서는 모래를 대신할 대체재의 개발이 요구되고 있는 실정이다. 석탄회의 공학적 성질은 모래와 유사하여 모래의 대체재로써의 CLSM에 적용 가능하며 친환경재료로써의 검증이 필요하게 되었다. 이중 식생에 관한 연구는 자연과 화합할 수 있는 중요한 연구분야로써 식생이 가능한 적정 pH를 만족시킬 경우 적용의 확대가 가능할 것으로 판단된다. 따라서 본 연구의 목적은 석탄회의 대량유효활용의 일환으로 석탄회를 활용한 CLSM을 pH가 식생이 가능하도록 저감하기 위한 방안으로, 양생방법과 중성화처리에 따른 pH의 저감효과를 확인하여 식생에 관한 기초 자료를 제공하는데 그 목적이 있다. 공시체의 제작은 일축압축강도 0.5~1.0㎫을 만족하며 매립회와 비회의 비율이 70:30인 것을 기준으로 하여 총 5가지 Case로 배합하였으며, CLSM의 알칼리 용출을 억제하기 위해 이인산암모늄 용액에 공시체를 침지하는 방법으로 중성화처리를 실시하였다. 연구결과 중성화처리와 양생에 의한 방법을 적용하기 이전의 CLSM는 pH 11이상의 알칼리성이었으나, 중성화처리와 양생방법을 적용한 이후의 pH는 9.5 이하로 저감시켜 식생이 가능한 조건을 만족하였다. Controlled low strength material(CLSM) is produced by mixing portland cement, fine aggregates, water and chemical admixtures. Sand is the most commonly used as the fine aggregates in the conventional CLSM. It is getting more and more difficult to obtain sand in Korea so it is required that the alternative materials be developed as the replacement of sand. Since the engineering characteristics of coal ash are similar to the sand, it becomes necessary to examine the application of the coal ash as the alternative material for CLSM and as the environment-friendly material. When the results meet the optimum pH level that plants can live, it can be expanded the scale of application of the study on the plant as the important field. This study was subjected to present the method to reduce the pH range of CLSM to a suitable condition that plants can survive. To verify this method, the care of neutralization was conducted by immersing the specimen to Ammonium monohydrogen phosphate. Before curing and neutralization, the maximum pH of developmental CLSM is approximately 11. However, the pH value of developmental CLSM has under 9.5 after peaceful curing and neutralization management.

중용량 공조에서 EHP와 GHP의 경제성 비교

김영일(Youngil Kim) 대한설비공학회 2008 설비공학 논문집 Vol.20 No.3

Cost related to building equipment accounts for about 85% of the life cycle cost of buildings. Therefore proper selection of air-conditioning system is important for reducing the overall cost of buildings. In this study, medium capacity EHP and GHP for air-conditioning a building with a floor area of 1,200㎡ are compared economically. To consider all the factors of initial and operation costs effectively, an annual equal payment method is proposed. For the initial cost, cost of equipment, construction, installation, electric facility, financial subsidy and tax cut is considered. Cost of basic electricity, energy(electricity and gas), space charge, labor, insurance and repair is considered for the operation cost. Under the assumptions made in this study, overall cost of EHP is less than that of GHP, but this is not absolute and different outcome may result if different assumptions are made. This study is useful for those who are interested in choosing an air-conditioning system that costs less for mid-size buildings with simple calculations.