• Smart Structures and Systems
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• 제21권5호
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• pp.705-713
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• 2018

High-speed rail (HSR) has been in operation and development in many countries worldwide. The explosive growth of HSR has posed great challenges for operation safety and ride comfort. Among various technological demands on high-speed trains, vibration is an inevitable problem caused by rail/wheel imperfections, vehicle dynamics, and aerodynamic instability. Ride comfort is a key factor in evaluating the operational performance of high-speed trains. In this study, online monitoring data have been acquired from an in-service high-speed train for condition assessment. The measured dynamic response signals at the floor level of a train cabin are processed by the Sperling operator, in which the ride comfort index sequence is used to identify the train's operation condition. In addition, a novel technique that incorporates salient features of Bayesian inference and time series analysis is proposed for outlier detection and change detection. The Bayesian forecasting approach enables the prediction of conditional probabilities. By integrating the Bayesian forecasting approach with time series analysis, one-step forecasting probability density functions (PDFs) can be obtained before proceeding to the next observation. The change detection is conducted by comparing the current model and the alternative model (whose mean value is shifted by a prescribed offset) to determine which one can well fit the actual observation. When the comparison results indicate that the alternative model performs better, then a potential change is detected. If the current observation is a potential outlier or change, Bayes factor and cumulative Bayes factor are derived for further identification. A significant change, if identified, implies that there is a great alteration in the train operation performance due to defects. In this study, two illustrative cases are provided to demonstrate the performance of the proposed method for condition assessment of high-speed trains.

• 수산해양기술연구
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• 제46권4호
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• pp.466-475
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• 2010

This study intends to present a direction for the better reforming of fishers'onboard living conditions and proposals for preparing for ratification of the Work in Fishing Convention by means of making a comparison between standards on recent national fishing vessel accommodation facilities and standards on the Work in Fishing Convention and Its Recommendation, 2007, ILO. For the most part of standards on national fishing vessel accommodation facilities are somewhat insufficient to satisfy the provisions in Annex III of the Convention. Considering by items on fishing vessel accommodation facilities, the standards on insect protector, noise and vibration, heating and air conditioning, lighting, persons per sleeping room, recreational facility are not provided in national law. Headroom, separation of accommodation, sleeping room floor area, mattress size, mess room, galley and food storage are partially sufficient for the Convention. In case of sanitary facilities, national standards are not sufficient for the Convention. The other side, facilities related safety of ship and crew such as emergency escape etc., are fully sufficient for the Convention. These insufficiencies caused by different types of fishing vessel depend on originality of fishing method and practices. In the comparison between equivalent tonnage about vessel's length on convention and calculated tonnage of national existing fishing vessel, the difference are 226tons about length 24m and 501tons about length 45m. For that reason, headroom, persons per sleeping room, cabin of sicker and injured, sanitary facilities may decide to use gross tonnage in place of length (L) and the alleviating measure basis of convention. But in case of standards on sanitary facilities which are unsufficient for the Convention, specially in coastal fishing vessel length basis should be adopted with alleviating basis for less than length 24m.

• 한국컴퓨터정보학회논문지
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• 제13권4호
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• pp.221-230
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• 2008

본 논문은 현재 사용하고 있는 비행정보 시스템 전체를 연구하고 차세대 유비쿼터스 비행정보시스템을 설계하였다. 지상의 서비스에서 좌석예약, 운송, 발권과 수화물 역추적, 그리고 비행기 내에서 고객을 위한 AVOD, 게임, TV, 휴대전화, 기내 인터넷 사용과 항공사와 관제업무인 ATC, ATS, 항공교통관제업무에 대한 유비쿼터스 비행정보시스템을 연구하였다. 연구 결과를 토대로 하여 차세대 유비쿼터스 비행정보시스템과 네트워크 보안, 시스템 보안에 필요한 정보보호 시스템을 설계하였으며, 기존의 유비쿼터스 비행정보시스템과 차세대 시스템을 비교 분석하여 개선점과 차이점을 도출하였다. 본 논문의 연구결과 세계 항공 및 관련산업에 비전을 제시하고 통신효율성과 고객의 만족도 및 비행 안전성과 효율성을 확보하여 비행정보산업에 새로운 지평을 개척할 것이다.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2007년도 춘계학술발표회
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• pp.109-113
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• 2007

요트에서는 가벼운 선체에 비해 고성능의 엔진을 탑재하게 되므로 엔진에서 발생하는 소음이 승조원 및 여객에 미치는 영향은 매우 크다. 최근에는 국내에서도 크루즈요트의 생산이 시도되고 있지만, 선박의 성능과 함께 기관소음의 차단기술이 구매자의 요구에 부응하지 못하고 있는 실정이다. 이와 같이 선실의 소음이 구매를 결정하는 중요한 척도로 되고 있지만, 메인엔진의 소음을 차단하기 위한 대책 이 부족한 형편이다. 그러나 최근에 발전되고 있는 모니터링설비와 지능제어시스템을 이용하면, 주 엔진의 주변을 고효율의 흡음벽으로 차단하여 기관실의 소음을 개선할 수 있다. 본 연구에서는 소음을 흡수할 수 있는 흡음벽의 성능을 높이기 위해 헬름홀츠 공명기의 원리를 적용에 대하여 연구하였다.

• 수산해양기술연구
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• 제57권3호
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• pp.228-235
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• 2021

Marine accidents caused by ships are very diverse, such as collision, sinking, stranding, grounding and fire. In particular, persons on passenger ship are unspecified and not trained, so it makes evacuation harder. For this reason, an evacuation plan that considers diverse situation in ship is needed. Effective evacuation planning requires training in consideration of various evacuation situations. In this paper, we investigated the time elapsed on evacuation in various situations from "HANMIR," the fishery training ship of the Korean Institute of Maritime and Fisheries Technology, using a Ship Evacuation Analysis Program (SEA-Pro) which is introduced to the society. We assumed a situation that has not only inconveniences for real training but also the possibilities of happening. Not all trainees are resting in their cabin, so we assumed positions such as they are in the bridge or engine room and applied fire and flooding situations. We assumed that the time for alerting the situation would be short, so we applied only elapsed time of movement. Those analyses could be helpful in three ways. The first is predicting the consequence of possible accidents. There are some conditions that can be appliable to this model, such as the decreased area of sight in those situations. The second is concluding the optimal limit of carriage and placement of safety instruments on building a new ship. The third is to be a base data for ships to make a new effective evacuation plan based on these analyses.

• 한국산업융합학회 논문집
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• 제24권3호
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• pp.363-371
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• 2021

Forest operations like timber harvesting have already been mechanized to reduce hazards to the worker and increase productivity. However, timber harvesting operations have still been considered potentially dangerous and expensive on steep terrain. Teleoperation, to control the timber harvesting machine at a distance, has the potential to improve the safety, productivity and efficiency of harvesting operations on steep terrain. To verify the effects of teleoperation, an experimental prototype system of a monitor image-based teleoperation was constructed using a real forestry machine. In this study, the productivity of excavator based grapple loader, which is one of the most used mechanized harvesting equipment in the timber production, was analyzed using time-study method. Factors like skill and age of operators, influencing loader productivity in timber loading operation were also evaluated by statistical analysis. Productivity analysis results showed that less experienced operators were more productive than experienced operators for teleoperation through image of monitors in the operator cabin. These results are shown to be unfamiliar to the monitor image and different loading operation pattern by operators. According to the results, the monitor image-based teleoperation system of forestry machine need to improve the resolution and installation position of camera. It was expected that additional studies will be needed for real-time remote control of forestry machine in the future.

• 한국항해항만학회지
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• 제44권3호
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• pp.264-274
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• 2020

로로 페리선은 급선회 시 선박의 선미부 객실의 증개축으로 인한 무게중심 상승, 과도한 화물적재, 발라스트 부족 등으로 인한 복원성 결여 및 고박 부실 등의 여러 가지 원인으로 전복되어 해저에 침몰하였다. 이 연구의 목적은 유체-구조 연성(Fluid-Structure Interaction; FSI) 해석기법을 이용하여 급선회에 따른 빠른 침수 및 전복에 이어 침몰사고로 진척된 원인을 과학적이고 정확하게 규명하고 분석하는 것이다. 이를 위해 사고 당시의 동영상과 사진들을 분석하여 시간에 따른 선박의 정확한 자세를 구현하고, 이에 따른 화물 이동과 선체 외부의 해수 유입구와 선체 내부에서의 유입된 해수의 이동 경로에 따른 해수 유입량을 실선 부양 시뮬레이션 및 유체정역학적 특성치 프로그램을 사용하여 정확히 검증하여 실선 침수·침몰 시뮬레이션을 수행하여 사고원인을 정확하고 객관적으로 규명하고자 하였다.

• 드라이브 ㆍ 컨트롤
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• 제13권2호
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• pp.10-18
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• 2016

A front-end loader (FEL) mounted on an agricultural tractor is one of the most commonly used implements to mechanize routine agricultural tasks. When the FEL is used with a loaded bucket, careful operation is required to maintain safety and avoid spillage when the tractor passes a bump because a change in the gravity center of the tractor due to varied loadings can affect the stability of the tractor. Use of a boom suspension system consisting of accumulators and orifice dampers can be instrumental in reducing pitching vibrations while increasing the handling performance of the FEL-mounted tractor. The objective of this research was to reduce bump shocks by adding an orifice and a flow control valve to the original hydraulic circuit composed solely of accumulators. A simulation study was performed using the SimulationX program to investigate the effects of an accumulator and an orifice-throttle damper on bump shocks. Results showed that the peak pressure on a boom cylinder and the vertical acceleration of a bucket were significantly affected by use of both an accumulator and an orifice damper. In a field test conducted with a 75-kW tractor, the peak pressure of the boom cylinder, and the root mean square (RMS) vertical acceleration of the bucket and seat were reduced by on average, 23.0, 42.2, and 44.9% respectively, as compared to those measured with the original accumulator system, showing that an improved design for the accumulator hydraulic circuit can reduce bump shocks. Further studies are needed to design a tractor suspension system that includes the effects of cabin suspension and tires as well as dynamic analysis.

• 항공우주정책ㆍ법학회지
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• 제34권1호
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• pp.39-77
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• 2019

국제항공운송에 종사하는 승무원은 업무의 성격상 여러 나라에서 근로를 제공하게 된다. 국제사법에 의하면 일상적 노무제공지는 국제근로계약의 준거법 결정(제28조 제2항), 국제재판관할의 결정(제28조 제3항, 제4항)에서 중요한 역할을 수행한다. 일상적 노무제공지는 국제재판관할과 준거법의 결정을 위하여 EU에서 제창된 개념으로, 국제항공법에서 항공안전을 확보할 목적으로 승무원의 피로관리를 위해 도입된 개념인 모기지(母基地)와 입법목적이 서로 달라, 일상적 노무제공지와 모기지는 같은 개념이라고 볼 수 없다. 승무원의 일상적 노무제공지를 결정하기 위해서는 (i) 승무원이 근무를 시작하고 종료하는 곳, (ii) 승무원이 업무를 수행하는 항공기가 주로 주기(駐機)된 곳, (iii) 사용자가 전달한 지시사항을 알게 되고 근무활동을 조직하는 곳, (iv) 근로계약상 승무원이 거주할 의무가 있는 곳, (v) 사용자가 제공하고 승무원이 사용할 수 있는 사무실이 있는 곳, (vi) 승무원이 업무에 부적합하거나 징계사유가 발생할 때 참석할 의무가 있는 곳 등을 종합적으로 고려하여야 한다. 그런데 위에서 열거한 사항은 모두 모기지 소재지와 동일하므로, 승무원의 일상적 노무제공지를 결정할 때 모기지를 가장 중요한 요소로 고려하는 것이 타당하다. 이와 달리 기적국을 일상적 노무제공지로 보아서는 안 된다. 대상사안에서 CJEU는 국제항공운송에 종사하는 객실승무원의 일상적 노무제공지에 관하여 최초로 판단기준을 제시하였는바, 이는 우리나라 국제사법의 모범이 되었던 브뤼셀 규정의 해석이므로, 국제항공운송 승무원에 관하여 국제사법상 일상적 노무제공지의 개념을 이해하는데 많은 도움이 될 것으로 보인다.