• Journal of Electrochemical Science and Technology
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• 제14권3호
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• pp.205-214
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• 2023

Soil salinity is becoming one of the most devastating environmental hazards over the years. Soil investigation involves fast, low cost and non disturbing methods to measure soil characteristics for both construction projects as well as for agricultural use. The electrical resistivity of saline soils is greatly governed by salt concentration and the presence of moisture in soil matrix. Experimental results of this investigation highlight that there is a significant relationship between the electrical resistivity of soil samples mixed with chloride solutions (NaCl, KCl, and MgCl₂) at various concentrations, and soil physical properties. Correlations represented by quadratic functions were obtained between electrical resistivity and soil characteristics, namely, water content, degree of saturation and salt concentration. This research reveals that the obtained correlations between electrical resistivity, salt concentration, water content and degree of saturation are effective for predicting the characteristics of salt affected soils in practice, which constitute a governing element in the assessment of saline lands sustaining infrastructure.

• 한국컴퓨터정보학회논문지
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• 제26권11호
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• pp.1-9
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• 2021

3D-NAND 플래시 메모리는 평면적 구조인 2D-NAND 셀을 적층하는 방식으로 단위 면적당 고용량을 제공한다. 하지만 적층 공정의 특성상 각 레이어별 또는 물리적인 셀 위치에 따라 오류 발생 빈도가 달라질 수 있는 문제가 있다. 이와 같은 현상은 플래시 메모리의 쓰기/지우기(P/E) 횟수가 증가할수록 두드러진다. SSD와 같은 대부분의 플래시 기반 저장장치는 오류 교정을 위하여 ECC를 사용한다. 이 방법은 모든 플래시 메모리 페이지에 대하여 고정된 데이터 보호 강도를 제공하므로 물리적 위치에 따라 오류 발생률이 각기 다르게 나타나는 3D NAND 플래시 메모리에서는 한계를 보인다. 따라서 본 논문에서는 오류 발생률 차이를 보이는 페이지와 레이어를 K-means 머신러닝 알고리즘을 통해 군집으로 분류하고, 각 군집마다 차별화된 데이터 보호강도를 적용한다. 본 논문에서는 페이지와 레이어별로 오류 발생률이 현저하게 달라지는 내구성 테스트가 끝난 시점에서 측정된 오류 발생 횟수를 바탕으로 페이지와 레이어를 분류하고 오류에 취약한 영역에 대해서는 스트라이프에 패리티 데이터를 추가하여 차별화된 데이터 보호 강도 제공을 예시로 보인다. 본 논문에서는 기존의 ECC 또는 RAID 방식의 데이터 보호 구조와 비교하여 제안하는 차별화된 데이터 보호정책이 3D NAND 플래시 메모리의 신뢰성과 수명향상에 기여할 수 있음을 보인다.

• Journal of Radiation Protection and Research
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• 제34권3호
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• pp.115-120
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• 2009

1990년대 이후부터 현재까지 일련의 사건들은 - 1995년 러시아 국립공원에서 매설된 오염폭탄발견, 2001년 9/11 테러, 2003년 알카에다 오염폭탄 실험 증거 발견등 - 방사성물질 (본 논문에서 언급한 "방사성물질"은 "핵물질 사용후핵연료 방사성동위원소"를 말함)을 이용한 핵테러 및 방사능테러 (본 논문에서는 "핵테러 및 방사능테러"를 간단히 "핵테러/방사능테러"로 표시함)가 공상과학소설이 아닌 실제적으로 발생가능할 심각한 위협임을 보여준다. 이에 따라 세계는 새롭게 대두된 위협에 효과적으로 대응하기 위해 방사성물질에 대한 보안(security)과 물리적방호(physical protection)를 강화하고 방사성물질 불법거래 예방 및 대응체제를 구축하도록 요구하고 있다. 우리나라는 이러한 국제적 추세에 부응하기 위해, 관련 법 체제를 제 개정하고 국제협약 혹은 기구에 합의하거나 가입하였다. 본 논문에서는 핵테러/방사능테러 예방의 일환으로 방사성동위원소에 비해 상대적으로 복잡한 붕괴 과정을 가진 핵물질의 물리적 특성을 살펴보고, 현재 운영되고 있는 핵테러/방사능테러 탐지 장비들의 특성을 파악한다. 검토된 장비들의 특성과 함께 국외에서 국내로 불법 유입된 방사성물질이 목표 지점까지 도달되는 과정, 국내 지형적 특정 그리고 다중 방어적 개념을 고려하여 핵테러/방사능테러 탐지체계 구축 방안을 제안한다. 본 논문은 핵테러/방사능테러로부터 국민의 건강, 안전 그리고 환경을 보호하는데 중요한 기여를 할 것으로 판단된다.

• Journal of Radiation Protection and Research
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• 제26권3호
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• pp.321-326
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• 2001

Radionuclide X-ray fluorescence analysis is a method, which has many advantages for analysing various historic artefacts, as it is relatively cheap, sensitive and non-destructive, and it allows measurements in-situ. However, this analysis has also certain limitations especially concerning sensitivity to chemical elements only, irrespective of the compounds or chemical forms in which these elements have been bonded. In addition, light elements emitting very soft X-rays cannot be measured, and in order to detect a wide range of elements, it is necessary to carry out repeated measurements with different radiation sources. Despite these limitations, valuable information can be obtained about the composition of historic materials and data about the origin and age of these artefacts can be derived. Analyses of wall paintings, ancient metal sculptures or other objects of art provide the basis for historic considerations documented in our results for some objects belonging to the Czech cultural heritage. The results are promising. Thus it is expected that our laboratory will expand its work into more fields of the fine and applied arts.

• Nuclear Engineering and Technology
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• 제37권3호
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• pp.259-264
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• 2005

This paper presents a vital area identification (VAI) method based on the current fault tree analysis (FTA) and probabilistic safety assessment (PSA) techniques for the physical protection of nuclear power plants. A structured framework of a top event prevention set analysis (TEPA) application to the VAI of nuclear power plants is also delineated. One of the important processes for physical protection in a nuclear power plant is VAI that is a process for identifying areas containing nuclear materials, structures, systems or components (SSCs) to be protected from sabotage, which could directly or indirectly lead to core damage and unacceptable radiological consequences. A software VIP (Vital area Identification Package based on the PSA method) is being developed by KAERI for the VAI of nuclear power plants. Furthermore, the KAERI fault tree solver FTREX (Fault Tree Reliability Evaluation eXpert) is specialized for the VIP to generate the candidates of the vital areas. FTREX can generate numerous MCSs for a huge fault tree with the lowest truncation limit and all possible prevention sets.

• Journal of Radiation Protection and Research
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• 제17권1호
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• pp.31-41
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• 1992

라돈 자핵종의 알파 측정용 여과지 매질에 대한 평가를 위한 연구는 물리적 특성조사로 여과지의 정전하 충전과 역학적 강도가 조사된 후, 시료채취 전과 후 여과지에 부가되는 압력차로 여과지의 성질을 시험하였으며, 알파 스팩트럼분석으로 여과지내 부착된 라돈 자핵종의 에너지스펙트럼을 분석하여 성능지수를 계산한 후 여과지의 특성을 비교 평가하였다. 평가의 결과 새로운 여과지 매질은 과거의 표준인 Millipore AA보다 크게 유리한 점은 없었으나, 정전하가 문제되는 곳에서는 Metricel DM-800을 권고하였다. 또한 평가방법은 새로 개발될 여과지들의 물리적 특성과 매질의 수집효율을 고려하여 라돈 자핵종의 알파 측정용 여과지 매질 평가를 위해 유용하게 사용될 수 있을 것이다.

• Nuclear Engineering and Technology
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• 제53권9호
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• pp.2888-2898
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• 2021

Vital area identification (VAI) is an essential procedure for the design of physical protection systems (PPSs) for nuclear power plants (NPPs). The purpose of PPS design is to protect vital areas. VAI has been improved continuously to overcome the shortcomings of previous VAI generations. In first-generation VAI, a sabotage fault tree was developed directly without reusing probabilistic safety assessment (PSA) results or information. In second-generation VAI, VAI model was constructed from all PSA event trees and fault trees. While in third-generation VAI, it was developed from the simplified PSA event trees and fault trees. While VAIs have been performed for NPPs in full-power operations, VAI for NPPs in low-power and shutdown (LPSD) operations has not been studied and performed, even though NPPs in LPSD operations are very vulnerable to sabotage due to the very crowded nature of NPP maintenance. This study is the first to research and apply VAI to LPSD operation of NPP. Here, the third-generation VAI method for full-power operation of NPP was adapted to the VAI of LPSD operation. In this study, LPSD VAI for a few plant operational states (POSs) was performed. Furthermore, the operation strategy of vital areas for both full-power and LPSD operations was discussed. The LPSD VAI method discussed in this paper can be easily applied to all POSs. The method and insights in this study can be important for future LPSD VAI that reflects various LPSD operational states. Regulatory bodies and electric utilities can take advantage of this LPSD VAI method.

• 한국의류학회지
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• 제45권2호
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• pp.253-270
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• 2021

This survey provides research into developing knee braces to protect the knee against damage, reduce knee pain, and strengthen the knee. A total of 235 surveys were conducted from December 2019 to January 2020. The subjects were adults in their 20s and over who lived in the Seoul metropolitan area and had experience of using knee braces. In terms of age differences, subjects over 60 years of age purchased knee braces mostly to secure a reduction of pain (ROP), whereas subjects in their 20s and 30s purchased knee braces for physical shock protection (PSP). Subjects in their 40s and 50s purchased knee braces for improvement of muscle movement (IMM). There was no significant difference in shape, material, and locking method based on the reason for wearing the knee brace. These results show that it is conceivable and maybe preferable to produce different knee braces-with a variety of shapes, materials, and locking materials-according to the reason behind wearing a knee brace. Knee braces are worn currently without any differentiation despite the findings of this study. In particular, we argue the need for functional and differentiated development of knee braces specifically for PSP, ROP, and IMM.

• Nuclear Engineering and Technology
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• 제56권6호
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• pp.2428-2435
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• 2024

Training for radiation protection and control requires a visual understanding of radiation, which cannot be perceived by the human senses. Trainees must also master the effective use of measuring instruments. Traditionally, such training has exposed trainees to radiation sources. Here, we present a novel e-training strategy that enables safe, exposure-free handling of a radiation measuring tool called a survey meter. Our mixed reality radiation-training system merges the physical world with a digital one. Collaborating with a mixed reality headset (HoloLens 2), this system constructs a mock-up of a survey meter in real-world space. The HoloLens 2 employs a browser-based application to visualize radiation and to simulate/share the use of the survey meter, including its physical movements. To provide a dynamic learning experience, the system adjusts the survey-meter mock-up readings according to the operator's movements, distance from the radiation source, the response time of survey meter, and shielding levels. Through this approach, we expect that trainees will acquire practical skills in interpreting survey-meter readings and gain a visual understanding of radiation in real-world situations.

• 대한물리치료과학회지
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• 제8권1호
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• pp.735-744
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• 2001

After providing the purpose, scope and methods of present study in the first chapter. the second chapter discusses a theoretical overview on the social implication of medical expenditure and the medical insurance program for the aged population. In conclusion, to realize the reduction of aged population's medical expenditures, some possible plans are conceivable. Firstly, the payment level of medical insurance should be upgraded and the insurance coverage in oriental medicine treatment and the drug-store protection program need to be implemented. Secondly, the medical facilities and man-power have be expanded for the sake of reducing the social and geographical distances the aged population has to overcome to receive the medical benefits. Thirdly, the expansions of medical services for the home-stay aged are all the more required. Finally, a wide range of programs needs to be augmented to promote health for the aged population.