분위수 공적분 모형과 해운 경기변동 분석

김현석 한국항만경제학회 2022 韓國港灣經濟學會誌 Vol.38 No.2

In this study, we estimate the quantile-regression framework of the shipping industry for theCapesize used ship, which is a typical raw material transportation from January 2000 to December 2021. This research aims two main contributions. First, we analyze the relationship between the Capesize used ship, which is a typical type in the raw material transportation market, and the freight market, for which mixed empirical analysis results are presented. Second, we present an empirical analysis model that considers the structural transformation proposed in the Hyunsok Kim and Myung-hee Chang(2020a) study in quantile-regression. In structural change investigations, the empirical results confirm that the quantile model is able to overcome the problems caused by nonstationarity in time series analysis. Then, the long-run relationship of the co-integration framework divided into long and short-run effects of exogenous variables, and this is extended to a prediction model subdivided by quantile. The results are the basis for extending the analysis based on the shipping theory to artificial intelligence and machine learning approaches. 본 연구는 2000년 1월부터 2021년 12월까지의 대표적 원자재 운송 수단인 Capesize 중고선가를 대상으로 해운산업에 대한 분위수 모형을 추정한다. 본 연구는 두 가지 학술적 기여를 목표로 한다. 첫째, 혼재된 실증분석 결과가 제기되는 원자재 운송 시장의 대표적 선종인 Capesize 중고선과 운임시장의 연관성을 분석한다. 둘째, 분위수 회귀로 김현석·장명희(2020a) 연구에서 제기하는 구조변환을 고려하는 실증분석 모형을 제시한다. 분석 결과는 분위수 모형은 시계열 자료에서 구조변화를 분석에 반영함으로써 오차의 불안정성으로 제기되는 문제를 우회할 수 있음을 확인한다. 그리고 공적분 모형의 장기 균형관계를 장기와 단기 추정변수를 통해 외생변수의 장·단기 영향으로 구분하고, 이를 분위별로세분화한 예측으로 확장한다. 이상의 추정결과는 해운 이론모형에 기반한 분석을 인공지능과 기계학습으로 확장할 수 있는 근거가 된다.

신재생에너지의 온실가스감축 기여도에 따른 지역별 보급전략

김현석,Kim, Hyun Seok 경북대학교 농업과학기술연구소 2014 慶北大農學誌 Vol.32 No.4

This study examines the contribution level of greenhouse gas(GHG) emission reduction and installation costs of renewable energy facilities. The GHG emission forecasts and industrial structures in the 16 regions of Korea are then analyzed to identify the proper supply of renewable energy sources for each region. The results show that water power is the most effective and efficient renewable energy source to reduce GHG emissions, followed by sunlight, wind power, geothermal heat, and solar heat, respectively. The 16 regions are then categorized into 4 groups based on their GHG emission forecast and industrial structure: high emission and manufacturing group, low emission and manufacturing group, low emission and service group, and high emission and service group. The proper supply of renewable energy sources for each group is then determined based on the contribution level and cost efficiency of GHG emission reduction.

가을을 걷는 길

金顯石 대한사립학교장회(구 대한사립중고등학교장회) 1979 私學 Vol.11 No.-

열심히 살아가는 국어교육과 후배들에게 이야기하는 선배의 작은 조언

김현석 대구대학교 국어교육과 2006 나랏말쌈 Vol.21 No.-

Facial injury patterns associated with stand-up electric scooters in unhelmeted riders

김현석,김우섭,김한구,강신혁,배태희 대한성형외과학회 2022 Archives of Plastic Surgery Vol.49 No.1

Background In recent years, the number of people riding stand-up electric scooters in South Korea has increased rapidly. This study analyzed the facial injury patterns associated with stand-up electric scooter-related trauma in patients who visited our emergency center. Methods In this retrospective review, we collected data from patients who had visited our emergency center for stand-up electric scooter-related trauma between January 1, 2018 and December 31, 2020. Results The average age of the patients was 26.7 years. Of the 73 patients, 47 were male and 26 were female, highlighting a male predominance. Seven patients were injured after alcohol consumption. None of the patients had worn helmets. Additionally, upon comparing the frequency of facial injuries according to the quarter of the year, the facial injury rate was higher in the second and third quarters than in the first and fourth quarters. Facial soft tissue injuries were classified into facial cosmetic subunits and analyzed according to their location. The highest number of injuries was on the chin (n=18, 20.9%). Of the 73 patients with stand-up electric scooter-related facial injuries, 16 had acute facial osseous fractures. The commonest acute facial osseous fractures were those of the orbit (n=7, 26.9%). Conclusions The patterns of facial trauma reported here can be helpful for quickly evaluating and treating patients with facial trauma related to stand-up electric scooters. Additionally, people riding stand-up electric scooters should be aware of the risks associated with facial trauma and the importance of wearing protective devices, such as helmets and masks.

Analysis of water in Loy Yang brown coal using solid-state 1H NMR

김현석,윤성호,Yusuke Nishiyama,Keiko Ideta,Jin Miyawaki,Yohsuke Matsushita,박주일,Isao Mochida 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.5

1H spin-echo MAS NMR and 1H saturated spin-echo MAS NMR were applied to classify the water in Loy Yang coal. Adsorbed water was examined based on the proton spectra, in which four major portions were identified according to the moisture contents. Free water could be quantified by analyzing the proton free induction decays (FIDs) obtained using the 1H saturated spin-echo technique. By comparing the proton intensity of the C–H portion to the aromatic and N portion in the proton spectra, and by evaluating the FIDs, the water in Loy Yang coal could be classified.

위상 이미지 상관기법을 이용한 시준거울의 자동정렬

김현석,김대석,이형철,김수현,Kim, Hyun-Suk,Tserendolgor, D.,Kim, Dae-Suk,Lee, Hyung-Chul,Kim, Soo-Hyun 한국광학회 2011 한국광학회지 Vol.22 No.1

본 연구에서는 현재 대부분 작업자에 의해 수동으로 이루어지고 있는 단색화장치 내 광학 요소간 광학정렬을 높은 반복도와 고속으로 수행할 수 있는 자동화 방안에 대해 논의하고자 한다. 단색 분광기의 시준거울 자동정렬을 위해 CCD센서를 이용한 위상이미지 상관기법을 핵심기술로 사용하였다. 실험결과 약 10초 내에 시준거울을 정밀하게 자동정렬 할 수 있다. A novel alignment method that can be used for aligning the collimating mirror employed in a monochromator is described. In most of the spectrometer industry, the alignment of optical components such as a focusing mirror, a grating and a collimating mirror has been performed manually so far. In this paper, we use a matchedfilter based image correlation technique for measuring the accurate image position which is used for aligning the collimating mirror. The experimental results show that with the proposed scheme automatic alignment can be completed within 10 seconds.

부유식 해양구조물의 플로트오버 설치용 LMU 최적설계

김현석,박병재,성홍근,이강수 한국전산구조공학회 2021 한국전산구조공학회논문집 Vol.34 No.1

A Leg Mating Unit (LMU) is a device utilized during the float-over installation of offshore structures that include hyperelastic pads and mating part. The hyperelastic pads absorb the loads, whereas the mating part works as guidance between topside and supporting structures during the mating sequence of float-over installation. In this study, the design optimization of an LMU for the float-over installation of floating-type offshore structures is conducted to enhance the performance and to satisfy the requirements defined by classification society regulations. The initial dimensions of the LMU are referred to the dimensions of those used in fixed-type float-over installation because only the location and the number of LMUs are known. The two-parameter Mooney–Rivlin model is adopted to describe the hyperelastic pads under given material parameters. Geometric variables, such as the thickness, height, and width of members, as well as configuration variables, such as the angle and number of members, are defined as design variables and are parameterized. A sampling-based design sensitivity analysis based on latin hypercube sampling method is performed to filter the important design variables. The design optimization problem is formulated to minimize the total mass of the LMU under maximum von Mises stress and reaction force constraints. LMU(Leg Mating Unit)는 해양구조물의 플로트오버 실치에서 활용되는 장비 중 하나로 충격을 흡수하는 부분과 결합부로 구성된다. 본 연구에서는 최적설계를 통해 부유식 해양구조물의 플로트오버 설치용 LMU의 성능을 개선하여 설계 요구 조건을 만족하는 설계를 개발하였다. 초기설계는 고정식 해양구조물의 플로트오버 설치용으로 개발된 것의 제원을 참조하였으며, 초탄성재료의 거동을 표현하기 위해 Mooney-Rivlin 모델을 활용하였다. 설계민감도해석 결과를 바탕으로 중요도에 따라 설계 변수들을 선별하였고, 진화 알고리듬 기반 최적설계를 수행하였다. 최적설계 문제에서 목적함수는 LMU의 중량이며, 제약 조건은 LMU에 작용하는 최대 폰-미세스 응력과 LMU의 성능을 평가할 수 있는 반발력이다.

저탄소 경제시스템 구축 전략 연구

김현석,정경화 에너지경제연구원 2010 에너지경제연구원 연구보고서 Vol.- No.-

수생식물을 이용한 축산폐수처리에 관한 연구

김현석,김경민,이수영,나규환 한국보건교육건강증진학회 1998 한국보건교육·건강증진학회 학술대회 발표논문집 Vol.- No.-