• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1058-1070
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• 2007

Internal and external railway management corporations are using the periodic replacement criteria of rail by accumulated passing tonnage and wear to maintain rails for servicing. However, internal the periodic replacement criteria of continuous welded rail(CWR) by accumulated passing tonnage is the one(50kg/m-5 million gross tonnage, 60kg/m-6 million gross tonnage) presented in Japan before. It was estimated with the fatigue life about 50kg N rail joints applied diesel train load but it wasn't applied to current conditions of track; elimination of rail joint, using the concrete slab track and operation of light train load and effect of welding, manufacturing technique, grinding of rail. Therefore, in this study, it was investigated the types of damage and cause in welded rails and examined standards and information resources. Also, this study presents preliminary data to revise the periodic replacement criteria of CWR by current accumulated passing tonnage in bending test of laid welded rail and a survey of track maintenance history of Seoul metro.

• Journal of the military operations research society of Korea
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• v.24 no.1
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• pp.41-57
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• 1998

Since the aircraft has a property of moving in the three-dimensional space, it may cause personally and financially critical damage in the case of an accident. Among the causes of aircraft accident, human factor has occupied about 70% of all accidents. Specially, fatigue among human's problems has been studied earlier than any other factor. Fatigue has been the cause of 75% of accidents that are related to human factor. So many studies have been conducted. But the direction of these studies mainly attach importance to the sleep loss and circadian rhythm. Limitation for flight time of ICAO is 8 hours per day, civil airlines in domestic line also adopt the limitation. But this rule is not based on human's performance but compromise between labor and management. The long-haul flight brings about a mental block to pilot. This mental block decreases performance of pilot and loses a lot of important information. So this may cause many accidents. This paper is to offer optimal flight time according to the amount of fatigue due to increasing flight time. The optimal flight time is searched through the field experiment. The experiment has adopted two methods. One is to examine pilot's objective fatigue accumulation rate through the critical fusion frequency, and another is to investigate pilot's subjective fatigue feeling through the fatigue subjective symptoms investigation table.

• Proceedings of the ESK Conference
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• 1997.10a
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• pp.152-159
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• 1997

인간공학을 적용하는데 있어 가장 기본적으로 다루어져야 할 것은 인간의 신체적, 심리적능력에 관한 연구이다. 특히 산업 현장에서 흔히 이루어지는 인간의 힘을 그 동력원으로 하는 수작업의 경우에 있어 서는 작업자가 직업적인 요인에 의해 피로가 누적되거나 신체적인 무리를 가져오지 않고 수행할 수 있는 안전한 작업기준의 설정이 필요하며 이를 위해서는 인간의 신체적 능격에관한 연구가 필수적이다. 특히 최근 들어 여성의 사회진출 기회가 다양해지고 있으며 많은 여성들이 육체적 노동을 필요로 하는 직업에 종사하고 있는 현실에서 한국여성들의 신체적 능력에 관한 자료가 절대적으로 부족한 상황이다. 따라서 본 연구에서는 현재 한국의 여성들이 활동하고 육체적 작업조건들이 적절하게 설정되어 있는지를 분석하기 위한 기초 자료로서 한국 여성들의 생리학적 작업능력(PWC:physiological work capacity)을 최대산소소모 능력(Maximal Oxygen Consumption: V0$_{2}$Max)의 관점에서 파악하고자 하였다. 또한 외국 여성의 생리 학적 작업능력과 한구 여성의 생리학적 작업능력을 비교 평가하여한국 여성에게 외국여성의 기준치를 적용 시키는 것이 적절한지를 분석해 보았다. 본 연구는 피실험자에게 위험부담을 주지 않는 Submaximal test의 연속적인 방법(continuous mathod)중 하나인 램프 테스트(Ramp test)를 사용하여 심박수(H.R)와 산소 소모 량(V0$_{2}$) 측정하여 최대심박수에서의 PWC를 추정하였다. 작업 부하는 자전거 에르고노미터와 트레드 밀을 사용하여부과하였다. 실험 결과로서 자전거 에르고미터의 경우 치대산소 소모량의 추정치 평균이 1818.79ml/min으로 나타 났고 트레드밀의 경우 2076.33ml/min으로 나타났다. 이 결과는 자전거 에르고 노미터의 결과는 자전거 에르고노미터의 결과가 트레드밀의 결과에 87.60%정도 나타났다.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.2
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• pp.117-126
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• 2002

Concrete containing discontinuous discrete steel fiber in a normal concrete is called steel fiber reinforced concrete(SFRC). Tensile as well as flexural strengths of concrete could be substantially increased by introducing closely spaced fibers which delay the onset of tension cracks and increase the tension strength of cracks. However, many properties of SFRC have not been investigated, especially properties on repeated loadings. Thus, the purposes of this dissertation is to study the flexural fatigue characteristics of SFRC considering cumulative damage. A series of experimental tests such as compressive strength, splitting tensile strength, flexural strength, flexural fatigue, and two steps stress level fatigue were conducted to clarify the basic properties and fatigue-related properties of SFRC. The main experimental variables were steel fiber fraction (0, 0.4, 0.7, 1, 1.5%), aspect ratio (60, 83). The principal results obtained through this study are as follows: The results of flexural fatigue tests showed that the flexural fatigue life of SFRC is approxmately 65% of ultimate strength, while that of plain is less than 58%. Especially, the behavior of flexural fatigue life shows excellent performance at 1.0% of steel-fiber volume fraction. The cumulative damage test of high-low two stress levels is within the value of 0.6 ∼ 1.1, while that of low-high stress steps is within the value of 2.4 ∼ 4.0.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.400-400
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• 2022

관로 내 빈번히 발생하는 수격압의 발생은 관망 구조물에 피로가 누적되고 관벽에 손상을 발생시켜, 관로 내 누수가 다양한 형태로 생성된다. 관 내 누수가 발생되는 경우 관 내부의 수격압의 발생 시 생성되는 부압으로 인하여 외부 물질이 관으로 흡수되거나 혼합되어 스케일과 미생물의 생성되는 등 관 내의 수질에 악영향을 끼치며 마찰을 증가시켜 통수능이 감소하고 관리에 추가적인 비용을 발생시킨다. 이러한 영향을 방지하기 위해 관 내에서 생성되는 누수를 탐지하기 위하여 수격압을 발생시켜 압력파를 분석하거나 추적을 수행하는 여러 가지 연구들이 수행되었다. 본 연구에서는 현장 관망과 연결된 100A 대구경 관로에 관로 수압 발생장치를 연결하여 기존의 수격압을 발생시켜 분석하는 방법 대신 안전하고 용이한 방법인 압력파를 주입하여 실험을 수행하였다. 실험을 통해 획득한 데이터를 시간상에서 분석하고 Fourier 변환을 통한 빈도상 분석과 Wavelet 분석으로 신호주기에서 누수가 미치는 영향을 파악하였다. 실험 결과에서는 누수에 의한 영향으로 반사파가 직접적으로 변형되는 형태보다 시스템 전체에서 반영되어 수두가 감쇠되는 형태로 나타났다. Fourier 변환을 통해 무누수 조건과 누수조건의 비교에서 누수의 유무에 따른 신호의 형태가 차이를 보였다. 앞선 연구들에서의 누수의 특정한 위치를 찾아내는 형태 대신 신호처리 후 분석을 통해 시스템 전체에서 일어나는 감쇠를 통해 누수 존재 유무를 판별하고자 한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.07a
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• pp.429-430
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• 2022

현재 코로나로 인한 각 나라의 입국 제한이 사라지면서 국내외 여행 예약률 증가에 따라 그만큼 비행기 예약도 늘어나고 있다. 그런데 객실 승무원의 근무 환경은 매우 열악하기 때문에 육체적, 정신적 피로를 누적되게 한다. 이는 승객에게 양질의 서비스를 제공할 수 없게 하고 안전사고를 대처하는 데 있어 문제가 된다. 본 논문은 객실 승무원이 스마트폰 앱을 이용하여 편리하게 객실 상황을 확인하고, 원격 제어하며 서빙카트를 조작하여 승객의 주문에 대한 서비스를 제공하는 '원격제어가 가능한 비행기 객실 관리 시스템'을 제안한다. 이 시스템을 이용함으로써 객실 승무원은 객실 상황을 판단하여 즉각적인 대처를 할 수 있고, 항공기 효율적 운용을 위한 안전성과 정시성을 확보하는 데 도움이 될 것이다.

• Journal of Digital Convergence
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• v.15 no.8
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• pp.501-509
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• 2017

The purpose of this study was to review the effects of the physical fatigue induced by overtraining on cognitive information processing and emotional change of athletes by neurophysiologic study. And to provide basic data for the athletes and coaches in the sports field to improve understanding of the overtraining symptoms from the brain physiological point of view. We reviewed the domestic and international academic materials and research reports published in the last 20 years using electronic databases and examined the literature that is consistent with the purpose of this study among the retrieved documents. Based on the reviewed literature, we examined the cognitive information processing and emotional change of the athlete according to the training, and overtraining can accumulate the fatigue of the body, which can cause severe side effects in terms of cognitive ability and emotional ability of athletes as well as deterioration of performance. The study using P300 and EEG cerebral hemispheric asymmetry difference indices also confirmed the possibility of a new approach to understand psychological and physiological effects of overtraining on information processing and emotional changes.

• Journal of Korean Society of Transportation
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• v.35 no.5
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• pp.423-433
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• 2017

During recent 5 years, it was recorded that 20% of total accident frequency and 30% of total number of death have been occurred due to drowsy driving. Drowsy driving accident is result from the loss of driving ability due to driver's accumulated fatigue. Continuous driving time can be measured as a surrogate variable to quantify the level of fatigue. The main purpose of this research is to investigate statistical correlation between the proportion of continuous driving vehicle (more than 2 hours) and the number of drowsy accidents. To carry this out, continuous driving time was measured using GPS route-guidance trajectory data. Also, accident frequency, traffic volume and segment length were collected to estimate safety performance function (SPF) for Jungbunearuk expressway in Korea. Through various types of estimated SPFs, statistical correlation was analyzed based on estimated statistical indices. This research can provide theoretical background for enforcement to regulate commercial vehicle driver's continuous driving time. In addition, throughout the trajectory data expansion, it is expected that strategy for anti-drowsy driving facilities installation can be established based on the suggested methodology.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.2
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• pp.133-145
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• 2010

Recently, due to advances in information technologies, the trend of tour types has been changing from package tour to independent tour. Independent tour is a tour which a traveler collect airplane ticket, travel destinations, sightseeing time, transport, lodging and plan traveling schedules by oneself. But the traveler has many difficulties for predicting tour schedules, due to lack of adequate information of travel destinations. In this study, traveling schedule prediction method which to minimize the cumulative fatigue of tourist for use of unnecessary transport is proposed using travelling salesman problem algorithm. It is considered moving time between sightseeing, sightseeing time on destination and traveling time for a day.

• Journal of Navigation and Port Research
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• v.40 no.6
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• pp.361-368
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• 2016

A ship's rolling motion can make crew and passengers sick and/or apply forces to the structure that cause damage.. Therefore bilge keels are equipped in most ships for anti-rolling. In special cases, anti-rolling tanks (ARTs), fin stabilizers, or gyroscopes can be installed. However, ARTs require a large area to install, and fin stabilizers and gyroscopes are costly to install and expensive to operate. This paper suggests a Anti-rolling pendulum (ARP) to reduce roll motion. ARPs acts like ARTs. However, the ARP has a circular shaped guidance arc instead of the string or wire of a simple pendulum. The device suggested has about 1/ 8 the weight and 1/ 6 the volume of a ART and is more effective. This study derives the nonlinear and linear differential equations of system motion.