• Nuclear Engineering and Technology
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• 제55권2호
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• pp.603-622
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• 2023

Human error (HE) is an important concern in safety-critical systems such as nuclear power plants (NPPs). HE has played a role in many accidents and outage incidents in NPPs. Despite the increased automation in NPPs, HE remains unavoidable. Hence, the need for HE detection is as important as HE prevention efforts. In NPPs, HE is rather rare. Hence, anomaly detection, a widely used machine learning technique for detecting rare anomalous instances, can be repurposed to detect potential HE. In this study, we develop an unsupervised anomaly detection technique based on generative adversarial networks (GANs) to detect anomalies in manually collected surveillance data in NPPs. More specifically, our GAN is trained to detect mismatches between automatically recorded sensor data and manually collected surveillance data, and hence, identify anomalous instances that can be attributed to HE. We test our GAN on both a real-world dataset and an external dataset obtained from a testbed, and we benchmark our results against state-of-the-art unsupervised anomaly detection algorithms, including one-class support vector machine and isolation forest. Our results show that the proposed GAN provides improved anomaly detection performance. Our study is promising for the future development of artificial intelligence based HE detection systems.

• 한국융합학회논문지
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• 제12권5호
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• pp.207-215
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• 2021

지게차는 전동 포크를 이용해 화물을 적재하고 운반하는 용도로 사용되는 산업용 장비로, 지게차로 인한 산업재해는 지속적으로 빈발하고 있다. 이러한 재해의 대다수는 작업자의 불안전한 행동에 기인하는 것으로 알려져 있으나, 지게차 작업에 초점을 두고 휴먼에러 관점에서 위험을 분석한 연구는 찾아보기 어렵다. 또한, 작업의 휴먼에러 위험을 파악하고 분석하기 위한 다양한 기법들이 개발되어 왔으나, 기법 간에 효과성이나 장단점을 직접적으로 비교한 연구는 드물다. 본 연구는 대표적인 휴먼에러 분석 기법인 SHERPA와 HE-HAZOP을 이용하여 지게차 작업에서의 불안전한 행동과 관련된 위험 요인을 분석하고 두 기법의 장단점을 비교한다. 지게차 작업 중 '하차작업', '자재이동 및 적재작업', '상차작업'의 3가지 대표적 작업을 대상으로 분석을 수행한 결과, SHERPA에 의해 118건의 에러와 34건의 개선대책이 도출되었으며 HE-HAZOP를 통해 139건의 에러와 54건의 개선대책이 도출되었다. 휴먼에러 위험 분석의 결과를 바탕으로 두 기법을 결과 건수, 접근방법, 원인분석, 위험성 평가, 개선방안 도출 방식 등 다양한 측면에서 비교하였다. 본 연구의 결과는 지게차를 사용하는 사업장에서 휴먼에러와 관련된 재해 위험을 줄이는 데 활용될 수 있다. 대상 작업과 여건에 맞는 휴먼에러 분석 기법을 선정하기 위한 가이드를 제공하기 위해서는 향후 다양한 작업을 대상으로 보다 많은 휴먼에러 분석 기법에 대한 비교 연구가 필요할 것으로 보인다.

• 대한인간공학회지
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• 제30권1호
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• pp.99-108
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• 2011

Almost all companies have paid much attention to the safety management ranging from maintenance to operation even at the stage of designing in order to prevent accidents, but fatal accidents continue to increase throughout the world. In particular, it is essential to systematically prevent such fatal accidents as fire, explosion or leakage of toxic gas at factories in order to not only protect the workers and neighbors but also prevent economic losses and environmental pollution. Though it is well known that accident probability is very low in NPP(Nuclear Power Plants), the reason why many researches are still being performed about the accidents is the results may be so severe. HRA is the main process to make preparation for possibility of human error in designing of the NPP. But those techniques have some problems and limitation as follows; the evaluation sensitivity of those techniques are out of date. And the evaluation of human error is not coupled with the design process. Additionally, the scope of the human error which has to be included in reliability assessment should be expanded. This work focuses on the coincidence of human error and mechanical failure for some important performance shaping factors to propose a method for improving safety effectively of the process industries. In order to apply in these purposes into the thesis, I found 63 critical Performance Shaping Factors of the eight dimensions throughout studies that I executed earlier. In this study, various analysis of opinion of specialists(Personal Factors, Training, Knowledge or Experience, Procedures and Documentation, Information, Communications, HMI, Workplace Design, Quality of Environment, Team Factors) and the guideline for construction of PSF were accomplished. The selected method was AHP which simplifies objective conclusions by maintaining consistency. This research focused on the implementation process of PSF to evaluate the process of PSF at each phase. As a result, we propose an evaluation model of PSF as a tool to find critical problem at each phase and improve on how to resolve the problems found at each phase. This evaluation model makes it possible to extraction of PSF succesfully by presenting the basis of assessment which will be used by enterprises to minimize the trial and error of construction process of PSF.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권2호
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• pp.782-795
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• 2019

Safety is always acritical focus of exploration of ocean resources, and it is well recognized that human factor is one of the major causes of accidents and breakdowns. Our research developed a dynamic human reliability assessment approach, Predicted Mean Vote-Cognitive Reliability and Error Analysis Method (PMV-CREAM), that is applicable to monitoring the cognitive reliability of oceanauts during deep-sea missions. Taking into account the difficult and variable operating environment of manned submersibles, this paper analyzed the cognitive actions of oceanauts during the various procedures required by deep-sea missions, and calculated the PMV index using human factors and dynamic environmental data. The Cognitive Failure Probabilities (CFP) were calculated using the extended CREAM approach. Finally, the CFP were corrected using the PMV index. This PMV-CREAM hybrid model can be utilized to avoid human error in deep-sea research, thereby preventing injury and loss of life during undersea work. This paper verified the method with "Jiaolong" manned submersible 7,000 m dive test. The"Jiaolong" oceanauts CR(Corrected CFP) is dynamic from 3.0615E-3 to 4.2948E-3, the CR caused by the environment is 1.2333E-3. The result shown the PMV-CREAM method could describe the dynamic human reliability of manned submersible caused by thermal environment.

• 전자공학회논문지S
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• 제34S권2호
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• pp.33-42
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• 1997

In this paper, a video coding method in wavelet transformed multi-resolution image using variable block sized motion estimation and multi-codebook is proposed. In the propoed method, the accuracy of motion estimation is increased by using variable block matching algorithm based on edge type of blocks which estimation is increased by using variable block matching algoritm based on edge type of blocks which is classified accoridng to the magnitude of wavelet coefficients in vertical subband and horizontal subband of the highest layer. Also, we increased the flexibility of bit allocation and decreased vector quantization error for motion compensated error transmission by using importance of each subband. Some experimental results confirm that he proposed mothod has fine reconstructed images without blocking effect at low bit rate, and especially reconstructs edges well to which human eyes are sensitive.

• Journal of Mechanical Science and Technology
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• 제19권spc1호
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• pp.272-282
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• 2005

A vehicle driving simulator is a virtual reality device which makes a man feel as if he drove an actual vehicle. Unlike actual vehicles, the simulator has limited kinematical workspace and bounded dynamic characteristics. So it is difficult to simulate dynamic motions of a multi-body vehicle model. In order to overcome these problems, a washout algorithm which controls the workspace of the simulator within the kinematical limitation is needed. However, a classical washout algorithm contains several problems such as generation of wrong sensation of motions by filters in tilt coordination, requirement of trial and error method in selecting the proper cut-off frequencies and difficulty in returning the simulator to its origin using only high pass filters. This paper proposes a washout algorithm with new tilt coordination method which gives more accurate sensations to drivers. To reduce the time in returning the simulator to its origin, an algorithm that applies selectively onset mode from high pass filters and return mode from error functions is proposed. As a result of this study, the results of the proposed algorithm are compared with the results of classical washout algorithm through the human perception models. Also, the performance of the suggested algorithm is evaluated by using human perception and sensibility of some drivers through experiments.

• 한국정보전자통신기술학회논문지
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• 제14권1호
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• pp.7-13
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• 2021

본 연구에서는 표적의 방향 탐지 오차를 최소화 시키는 방법을 제안한다. 수신 신호 위상차에 오차가 발생하면 표적 방향을 정확히 탐지 할 수 없다. 본 연구 제안 방법은 각 안테나에 입산한 신호에 대해서 실효치를 적용하여 위상을 획득한 후 최적의 신호 대 잡음비를 이용하여 위상 오차를 감소시킨다. 모의실험결과에서 안테나 간격이 반파장일 때, 표적 방향 탐지 확률이 가장 우수하고 신호 대 잡음비가 25dB일 때 방향 탐지 확률의 기존방법은 10-1.7이고 제안 방법은 10-3.3이다. 기존 방법의 표적 탐지 방향은 [-8°,8°]로서 2도의 오차를 나타내고, 제안 방법의 표적 탐지 방향은 [-10°,10°]로서 표적방향을 모두 정확히 탐지한다. 향후 분해능 감소에 따른 위상오차를 감소시키는 방법에 대한 연구가 필요하다.

• 비교문화연구
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• 제33권
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• pp.287-307
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• 2013

One cat caused a big wave in Russian literature. This cat revived the heroine of Russian classics. Her light breath was scattered in the world, in the cloudy sky and in the cold spring wind about one hundred years ago. And the cat gave an opportunity of turning to Russian classics to Russian readers. Thanks to this cat, a Russian dreamer changed his typical thinking, as well as many ordinary readers start to read works of creator of this wonderful cat. Pelevin accomplished these works with one cat, which he has made. Of course "Nika" is not only caused to make readers to return to Russian classics. I think, the cat and "Nika" are the symbols of writer's purpose in Russian literature. In this study the understanding of "Nika" is following the steps of realization of writer's purpose. In the second chapter it is analyzed to the textual relationship between "Nika" and "Light breath". Apart from existing analyses to be emphasized the succession of thematic aspect of two works as well. Existence of observers to each heroine stress this succession of thematic aspect of two works. In the third chapter it is analyzed the use of technique of mystification in "Nika". This intentional use of mystification has been demanded to read a "Nika" from another point of view(internal speculation of hero-narrator). The purpose of writer was to expose the cognitive error of a human being. I think this purpose was effectively explained by Pelevin's Buddhist world view which was introduced in his several works.

• 대한인간공학회지
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• 제18권1호
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• pp.41-53
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• 1999

The effect of menu width and depth on the efficiency of information search and menu preference was investigated to identify an optimal menu structure for EIG which reflects the characteristics of human information processing. Information search time increased stepwisely as the menu width exceeded 6 items and linearly as the level of menu depth increased. The linear relationship between the error rate and the number of depth levels seems to be caused by the increase in the items to be remembered. When a menu structure was constructed by combining different menu depths and widths, it was observed that making the menu width wider rather than the depth deeper allows better information search. The menu structure rated as the most preferable and the easiest to user was that of pyramidal form. Such a result seems to come from its structural similarity to general categories which people get used to and implies that one should consider user preference as well as efficiency of search when he/she designs an EIG menu.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제8권4호
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• pp.367-375
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• 2002

역운동학 알고리즘은 다관절체의 엔드 이펙터를 제어하기 위한 매우 유용한 방법이다. 대부분의 역운동학 처리 과정에서 주된 관심사는 다관절체가 가지는 자세의 형태 자체가 아니라 제어되는 다관절체의 엔드 이펙터의 위치와 방향이다. 그러나 삼차원 캐릭터 애니메이션과 같은 종류의 응용 분야에 있어서는 엔드 이펙터의 정확한 위치와 방향보다는 다관절체의 전체적으로 자연스러운 자세 자체가 훨씬 더 중요한 요소이다. 실제로 애니메이터가 기존의 역운동학 기법을 사용해서 인체와 같이 다수의 물리적인 제약조건을 가지는 인간형 삼차원 캐릭터의 자세를 자연스럽게 제어하기 위해서는 많은 시행착오를 겪어야만 하기 때문에 이를 보완하는 특별한 알고리즘이 요구된다. CCD(Cyclic Coordinate Descent) 알고리즘은 기하학적인 검색을 통해 원하는 위치에 엔드 이펙터를 위치시키는 해를 구하는 역운동학 방식의 하나로서 사용자 상호작용을 통한 다관절체의 자세 제어에 적합하다. 그러나 CCD 알고리즘의 해는 초기 자세에 강력하게 종속되어 있기 때문에 초기 자세에 따라서 서로 다른 많은 해들을 얻게 된다. 본 논문에서는 인간형 캐릭터의 자세 제어를 위해 균등 자세 지도를 이용한 귀납적 역운동학 알고리즘을 제안한다. 균등자세 지도의 학습 알고리즘은 인간의 다양한 자세를 왜곡 없이 양자화하기 때문에 균등 자세 지도를 이용해서 기술되는 모든 자세들은 사실적인 자세임을 보장한다. 그러므로 균등 자세 지도를 통해 계산된 다관절체의 엔드 이펙터가 원하는 삼차원 위치와 가장 가까운 자세를 추출해 냄으로써 자연스러운 자세를 가지는 역운동학의 결과를 얻을 수 있다. 이러한 방식은 키 프레임 기반 삼차원 캐릭터 애니메이션의 제작과 3차원 게임, 그리고 가상 현실 등의 분야에 유용하게 적용될 수 있다.