• 동력기계공학회지
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• 제6권4호
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• pp.68-72
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• 2002

For the evaluation of a flaw in a welded stainless steel by the Time of Flight Diffraction(TOFD) Method, we have made the reference specimen for experimentation. As a result, we could analyze a specific character and the inner state of the structure in a welded stainless steel and we came to the conclusion as followed. (1) For analyze the structure state of a section in a welded stainless steel through the optical microscope, we could have analyzed the generated shape and the location of a flaw and the inner parts of the structure state through the microscope of eighty magnification and two hundred magnification about the soundness, the heat affected zone(HAZ) and the welded part. (2) Through the comparison with the shape and the size of a flaw in the welded part about the conventional ultrasonic test and the TOFD Method, we could make an observation the special character of the TOFD Method and principles. (3) We analyzed and collected the merit of the TOFD Method on the basis of the experimental result by the shape and the size of a flaw in the inner welded parts. So, we made up a base that we could use as a basic data for a similar flaw like that. Through the study as mentioned above, we could make an observation the flaw detective method and principles used in the TOFD Method.

• 대한방사선기술학회지:방사선기술과학
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• 제45권5호
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• pp.397-405
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• 2022

Computed radiography (CR) systems, which convert an analog signal recorded on a cassette into a digital image, combine the characteristics of analog and digital imaging systems. Compared to digital radiography (DR) systems, CR systems have presented difficulties in evaluating system performance because of their lower detective quantum efficiency, their lower signal-to-noise ratio (SNR), and lower modulation transfer function (MTF). During the step of energy-storing and reading out, a baseline offset occurs in the edge area and makes low-frequency overestimation. The low-frequency offset component in the line spread function (LSF) critically affects the MTF and other image-analysis or qualification processes. In this study, we developed the method of baseline correction using mathematical morphology to determine the LSF and MTF of CR systems accurately. We presented a baseline correction that used a morphological filter to effectively remove the low-frequency offset from the LSF. We also tried an MTF evaluation of the CR system to demonstrate the effectiveness of the baseline correction. The MTF with a 3-pixel structuring element (SE) fluctuated since it overestimated the low-frequency component. This overestimation led the algorithm to over-compensate in the low-frequency region so that high-frequency components appeared relatively strong. The MTFs with between 11- and 15-pixel SEs showed little variation. Compared to spatial or frequency filtering that eliminated baseline effects in the edge spread function, our algorithm performed better at precisely locating the edge position and the averaged LSF was narrower.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1996년도 추계학술대회논문집
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• pp.47-55
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• 1996

This study developed a comprehensive and easily applicable nuclear reactor control system evaluation method using reactor operators behavioral and mental workload database. A proposed control panel design cycle consists of the 5 steps: (1) finding out inconvenient, erroneous, and mentally stressful factors for the proposed design through evaluative experiments, (2) drafting improved design alternatives considering detective factors found out in the step (1), (3) comparative experiements for the design alternatives, (4) selecting a best design alternative, (5) returning to the step (1) and repeating the design cycle. Reactor operators behavioral and mental workload database collected from evaluative experiments in the step (1) and comparative experiments in the step (3) of the design cycle have a key roll in finding out defective factors and yielding the criteria for selection of the proposed reactor control systems. The behavioral database was designed to include the major informations about reactor operators' control behaviors: beginning time of operations, involved displays, classification of observational behaviors, dehaviors, decisions, involved control devices, classification of control behaviors, communications, emotional status, opinions for man-machine interface, and system event log. The database for mental workload scored from various physiological variables-EEG, EOG, ECG, and respir- ation pattern-was developed to indicate the most stressful situation during reactor control operations and to give hints for defective design factors. An experimental test for the evaluation method applied to the Compact Nuclear Simulator (CNS) installed in Korea Atomic Energy Research Institute (KAERI) suggested that some defective design factors of analog indicators should be improved and that automatization of power control to a target level would give relaxation to the subject operators in stressful situation.

• 대한의용생체공학회:의공학회지
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• 제25권4호
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• pp.253-259
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• 2004

본 연구에서는 디지털 X-선 영상시스템의 최적화 설계를 위하여 몬테카를로 방법을 이용한 영상모의실험용 코드를 visual $C^{++}$ 프로그래밍 언어를 사용하여 개발하였다. 디지털 X-선 영상시스템으로 Gd$_2$O$_2$S(Tb) 섬광체 및 광센서 어레이를 고려하였으며, 일반적인 실험 환경을 모사하기 위해 2차원 평행 그리드를 포함시켰다. X-선과 피사체, 그리드 및 섬광체와의 반응, 그리고 섬광체에서 발생된 빛의 거동 및 광센서 어레이에서의 수집을 몬테카를로 방법을 이용하여 모사하였다. Gd$_2$O$_2$S(Tb) 섬광체의 두께는 66$\mu\textrm{m}$로 설정하였으며, 광센서 어레이의 픽셀 피치는 48$\mu\textrm{m}$ 그리고 픽셀의 포맷은 256${\times}$256으로 가정하였다. 다양한 모의실험조건에서 X-선 영상을 획득한 후 객관적인 영상시스템의 성능평가 지표인 SNR(signal-to-noise ratio), MTF(modulation transfer function), NPS(noise power spectrum), DQE(detective quantum efficiency) 등을 계산하였으며, 이를 통해 화질을 평가하였다. 본 연구에서 개발된 영상모의실험 코드는 다양한 디지털 X-선 영상시스템에 대해 여러 설계변수들에 대한 성능을 예측함으로써 영상시스템 최적설계에 활용될 수 있다.

• 수산경영론집
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• 제42권3호
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• pp.41-61
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• 2011

Marine protected Areas(MPAs) are specially designated zones of the sea that are designed to secure operation of ecosystem function and to restore marine ecosystem to the original state by excluding all detrimental human activities. MPAs have been proposed in many countries as means of realizing sustainable fisheries and recently MPAs are newly receiving attention as precautionary measure for global warming and climate change. The purpose of this paper is to examine the possibility of MPAs as fisheries management tools through a wide range of literature analysis and to suggest necessity of fisheries purpose of MPAs in Korea. Establishment of marine protected area can accompany various economic benefits such as restoration of marine environment, preservation of habitats, promotion of marine tourism and so on. Especially, a lot of case studies suggested that MPAs may bring out benefits to the fishing industry as a result of enhanced stocks. Fisheries benefits of MPAs on targeted species include increased abundance, increased mean individual size and age, increased reproductive output, enhanced recruitment inside and outside refuge, maintenance of genetic diversity of stocks, and enhanced fishery yields in adjacent fishing grounds, so called spill-over. MPAs for ecosystem conservation and protection of coastal wetland have been applied appropriately and effectively, however, the Korean MPAs system is still detective due to absence of fisheries purpose MPAs. Finally, suggestions for Korean MPAs can be summarized as following four recommendations; to establish number of small-scale MPAs rather than few large MPAs, to designate island and its surrounding areas as reserve, to consider MPA design with stock enhancement program, and to undertake co-management with Eochon-Gye, the traditional coastal community in Korea.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.385-388
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• 2002

We measured and evaluated digital, pre-sampling and overall imaging properties (characteristic curves, Modulation Transfer Function (MTF), Wiener spectra (WS), Noise Equivalent Quanta (NEQ) and Detective Quantum Efficiency (DQE)) for the direct type and indirect type of Flat-Panel Detector (FPD). First, the digital and overall characteristic curves of the both types of FPD had more wide dynamic range than that of the S/F system. Second, the pre-sampling and overall MTF of the direct-type FPD were superior to those of the indirect-type FPD. Third, for identical exposures, the digital and overall WS of the direct-type FPD were similar or worse than those of the indirect-type FPD, and for larger exposure, the digital WS of the both types of FPD were smaller, but overall WS of the both types of FPD were larger. Fourth, the digital and overall NEQ and DQE of the direct-type FPD were worse than both NEQ and DQE of the indirect-type FPD at lower spatial frequencies, but were better at higher spatial frequencies.

• 한국의류학회지
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• 제39권2호
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• pp.233-246
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• 2015

Focus on Digital Fashion Image, the conceptual framework for the thesis is established from Virtuality in Digital Art. Formative characteristics and aesthetic characteristics were studied by classifying the Digital Fashion Image applied and expressed by digital media and technology. A detective research method was used for a case study. A literature study for case-by-case data was analyzed with focus on the works expressing fashion that utilized digital media and technology since the 2000s. Through this study, the Digital revolution has created the socio-cultural impact of a Virtual representation to implement technology and fashion culture that finds ways to take advantage of the image shown in a Digital Fashion Media by understanding Virtuality. The results are as follows. First, it was a re-formation of the fashion culture through the experience of virtuality with mental zone parameters between the media 'Mediation Code'. Reflect the reality of the virtual environment as represented by a cultural image of fashion brands and fashion that reset the team relationship and formed a Homo Ludens cultural code. Second, 'Interactive Exchange' acts on the exchange interaction between the method of digital technology, the human and the machine as well as the technical interoperability of network elements and techniques. This exchange is applied to fashion images that express emotion. Forming personalized fashion items and the user interactively storage that expresses the interactive exchange to forward the identity of the emotional fashion by a change in the message delivery system fashion. Third, the emphasis on intuitive artistic expression 'Synesthesia Immersion' induces a sense of immersion and excitement through the fusion of the interconnected. Enhance a visual image in fashion sensory representation and maximize a tactile and visual virtual reality involvement.

• 한국화재소방학회논문지
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• 제24권3호
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• pp.58-65
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• 2010

최근 들어 발생하고 있는 화재 사고는 재산 피해 및 인명 피해 측면에서 점점 대형화 되어가고 있는 추세지만, 이를 효과적으로 예방하고 조치할 수 있는 종합적인 차원의 화재안전기술 개발을 필요로 한다. 특히, 초고층 빌딩이 우후죽순으로 들어서고 있는 지금, 새로운 패러다임의 진보된 화재안전기술의 필요성이 대두되고 있다. 따라서, 본 논문에서는 세 가지 종류의 산소소모법 칼로리미터인 bench scale calorimeter(cone calorimeter/ISO 5660/Avg.500Kw), Medium scale calorimeter(Room corner tester, Single burning Item/ISO 9750, EN 13823/Avg.3MW), and large scale calorimeter(Industry calorimeter/Avg. 10MW)에 의한 열방출율 측정과 이때 발생된 연기발생량과의 상관관계를 찾고자 한다. 이렇게 찾아진 열방출율과 연기발생량과의 상관관계를 활용하여 새로운 개념의 연기감지기를 개발하여 화재 사고 시 인명피해 및 재산피해를 최소화 하고 궁극적으로 이러한 이론을 바탕으로 초고층화 되고 있는 건축물에 새로운 개념의 화재경보 및 피난 시스템의 개발 및 적용이 가능하리라 예상된다.

• 대한방사선기술학회지:방사선기술과학
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• 제42권4호
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• pp.259-263
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• 2019

This study was purpose to compare image quality of Indirect digital radiography (IDR) system by using the International electro-technical commission standard(IEC 62220-1) which were applied to IEC in medical imaging. To evaluation the analysis of Modulation transfer function(MTF) measurements edge device each angle by using edge method. In this study, Aero (Konica, Japan) which is Indirect flat panel detector(FPD) was used, the size of image receptor matrix $1994{\times}2430$ which performed 12bit processing and pixel pitch is $175{\mu}m$. In IEC standard method were applied to each angle were compared. The results of shown as LSF at $2.0^{\circ}$ and $3.0^{\circ}$ angeles. Shape is constant and shows smooth shape. The amount of data seemed reasonable and 2.19 cycles/mm and 2.01 cycles/mm at a spatial frequency of $2.0^{\circ}$ and $3.0^{\circ}$ at an MTF value of 0.1. At an MTF value of 0.5, the spatial frequencies were $2.0^{\circ}$ and 1.11 cycles/mm and 0.93 cycles/mm at an angle of $3.0^{\circ}$. This study were to evaluate MTF by setting the each $2{\sim}3^{\circ}$ each angle and to suggest the quantitative methods of measuring by using IEC.

• 산업경영시스템학회지
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• 제45권1호
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• pp.31-40
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• 2022

Six Sigma is a philosophy and systematic methodology for quality improvement. It encourages continuous quality improvement efforts to achieve the ideal goal of 6σ. Sigma(σ) is a statistic representing the standard deviation of the normal distribution, and 6σ level means a level where the tolerance of the specification is six times the standard deviation of the process distribution. In terms of the defective rate, the 6σ level achieves the 0.002 defectives per one million units. However, in the field, the 6σ level is used in the sense of achieving 3.4 defects per one million opportunities, which shows a large gap from the 6σ level in the statistical viewpoint. This is because field practitioners accept a 1.5σ shift of the mean of process when calculating the defective rate under sigma level. It said that the acceptance of 1.5σ shift of the mean is from experience, but there is no research or theoretical explanation to support it logically. Although it is a non-scientific explanation based on experience, considering that there has been no objection to the 1.5σ shift for a long time and it is rather accepted, it is judged that there is a reasonable basis for the 1.5σ shift. Therefore, this study tries to find a reasonable explanation through detective power of control chart via the run-rules to the 1.5σ shift empirically recognized by practitioners.