• Structural Engineering and Mechanics
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• 제42권1호
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• pp.55-72
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• 2012

Precast-cast insitu concrete bridge construction is widely practiced for small to medium span structures. These bridges consist of precast pre-stressed concrete beams of various cross-sections with a cast in-situ reinforced concrete slab. The connection between the beams and the slab is via shear links often included during the manufacturing process of the beams. This form of construction is attractive as it provides for standardisation, reduced formwork and construction time. The assessment of the integrity of shear connectors in existing bridges is a major challenge. A procedure for assessment of shear connectors based on vibration testing and finite element model updating is proposed. The technique is applied successfully to a scaled model bridge model and an existing bridge structure.

• 대한환경공학회지
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• 제39권12호
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• pp.698-705
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• 2017

전과정평가 기법을 적용하여 재생 플라스틱을 사용한 휴대폰 충전기의 전과정 환경영향을 정량화하고, 신재 플라스틱과 재생플라스틱의 환경영향을 비교하였다. 충전기의 제조전, 제조, 유통, 사용 및 폐기를 포함하는 전과정 단계별로 자원고갈, 산성화, 부영양화, 지구온난화, 오존층고갈, 광화학산화물생성 환경영향을 분석하였다. 자원고갈 및 지구온난화 영향범주에서는 충전기의 사용단계 환경영향이 각각 94.4%, 70%를 차지하여 가장 큰 환경영향을 나타냈고, 그 외 영향범주에서는 제조전단계의 환경영향이 98% 이상을 차지하였다. 사용단계의 경우 충전기에 의해 소모되는 전력이 주요 원인이고, 제조전단계 경우 PBA (Printed Board Assembly)와 외장 Case 제조공정이 주요 원인이었다. 외장 Case에 사용되는 재생 PC (Polycarbonate)의 환경개선 효과를 정량화하기 위해 재생 PC와 신재 PC 각 1 kg 생산할 때의 환경영향을 평가하였다. 재생 PC는 신재 PC 대비 자원고갈영향은 30% 수준이며 다른 영향범주에서는 5% 미만으로 잠재적인 환경개선효과가 큰 것으로 분석되었다. 연구에 활용된 주요 데이터 및 가정에 대해 민감도 분석을 수행하였고, 총 12개 항목 분석결과 모든 항목에서 민감도는 10% 미만으로 도출되어 연구 결과의 신뢰도는 높다고 판단된다. 이 연구결과를 통해 충전기의 친환경성 개선을 위해서는 PBA의 소형/경량화 설계, 충전효율의 개선, 재생플라스틱 사용 확대가 전과정 환경영향을 줄이는데 중요한 설계 인자임을 확인하였다.

• 한국산업보건학회지
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• 제31권4호
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• pp.304-316
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• 2021

Objectives: By comparing and analyzing the legal system for risk assessment in South Korea with other advanced countries, the study is designed to identify the key elements of risk assessment and seek improvement measures while focusing on solutions to the execution of risk assessment violations. Methods: The study started with an awareness of the need to improve the legislation on the risk assessment of businesses in Korea. In order to reflect this problem consciousness in Korea's industrial safety and health legislation, risk assessment legislation in Japan, Britain, Germany, and Korea was analyzed in comparative terms through the literature. Results: Unlike the other advanced countries, the concept of risk assessment is defined in Korea in a broad sense that includes measures to reduce risk, and risk assessment in the manufacturing and design stages is not institutionalized. In the case of worker participation, there is a problem regarding effectiveness. It is problematic that compared to the other foreign countries there is a possibility that general risk assessment will be neutralized because it is recognized as a uniform general risk assessment for a particular risk assessment, as well as inadequate risk assessment. Conclusions: The areas diagnosed with problems compared to the legislation in other advanced countries should be improved by revising laws and administrative rules and supplementing the explanatory guidelines, etc. by referring to the legislation of these countries. In particular, the issue of enforcement for violations of risk assessment must be improved in order to ensure the effectiveness of risk assessment.

• 한국환경보건학회지
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• 제47권5호
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• pp.432-445
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• 2021

Background: The European Centre for Ecotoxicology and Toxicology of Chemicals' Targeted Risk Assessment (ECETOC TRA) tool has been recognized by EU REACH as a preferred approach for calculating worker health risks from chemicals. Objectives: The applicability of the ECETOC TRA to occupational exposure estimation from industrial uses of methanol was studied by inputting surveyed and varied parameters for TRA estimation as well as through comparison with measured data. Methods: Information on uses of methanol was collected from seven working environment monitoring reports along with the measured exposure data. Input parameters for TRA estimation such as operating conditions (OCs), risk management measures (RMMs) and process categories (PROCs) were surveyed. To compare with measured exposures, parameters from the surveyed conditions of ventilation but no use of respiratory protection were applied. Results: PROCs 4, 5, 8a, 10, and 15 were assigned to ten uses of methanol. The uses include as a solvent for manufacturing sun cream, surfactants, dyestuffs, films and adhesives. Methanol was also used as a component in a release agent, hardening media and mold wash for cast products as well as a component of hard-coating solution and a viscosity-controlling agent for manufacturing glass lenses. PROC 8a and PROC 10 of a cast product manufacturer without LEV (local exhaust ventilation) and general ventilation as well as no respiratory protection resulted in the highest exposure to methanol. Assuming the identical worst OCs and RMMs for all uses, exposures from PROC 5, 8a, and 10 were the same and the highest followed by PROC 4 and 15. The estimation resulted in higher exposures in nine uses except one use where measured exposure approximated exposures without RMMs. Conclusions: The role of ECETOC TRA as a conservative exposure assessment tool was confirmed by comparison with measured data. Moreover, it can guide which RMMs should be applied for the safe use of methanol.

• 터널과지하공간
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• 제32권1호
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• pp.78-92
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• 2022

본 연구에서는 스마트 마이닝 기술의 수준을 체계적이고 구조화된 방법으로 평가할 수 있는 스마트 마이닝 기술 수준 진단평가 모델을 제안하였다. 이를 위해 스마트 마이닝의 성숙도를 정의하였으며, 제조업에서 활용되는 스마트 공장 진단평가 모델(KS X 9001-3)을 참조하여 스마트 마이닝 기술 수준 진단평가 모델의 세부평가항목 도출하였다. 기존의 체계를 유지하면서 기존 46개의 세부평가항목을 광업에 적합하도록 수정하였으며 추진전략, 프로세스, 정보시스템과 자동화, 성과 부문에서 총 29개의 세부 평가 항목을 도출하였다. 이를 토대로 스마트 마이닝 기술 수준 진단평가 설문지를 설계하였고, 국내의 철광산을 연구지역으로 설정한 다음 스마트 마이닝 기술 수준을 평가하였다. 연구지역의 스마트화 수준은 레벨 2로 나타났으며, 일반 제조업의 평균 스마트 수준과 비교했을 때 40% 정도 낮은 수준에 있음을 유추할 수 있었다. 또한, 개발된 모델을 이용하여 스마트 마이닝의 도입, 운영, 고도화의 단계별로 광산의 취약한 부분을 인지하고 투자 및 개선 방향을 제시할 수 있었다.

• 한국환경보건학회지
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• 제37권1호
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• pp.12-21
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• 2011

The objective of this study is to review retrospective exposure assessment methods used in wafer fabrication operations to determine whether adverse health effects including mortality or cancer incidence are related to employment in particular work activities and to recommend an appropriate approach for retrospective exposure assessment methods for epidemiological study. The goal of retrospective exposure assessment for such studies is to assign each study subject to a workgroup in such a way that differences in exposure within the workgroups are minimized, as well as to maximize the contrasts in exposure between workgroups. To reduce the misclassification of exposure and to determine if adverse health effects including mortality or cancer incidence are related to particular work activities of wafer fabrication workers, a minimum requirement of work history information on the wafer manufacturing eras, job and department at which they were exposed should be assessed. Retrospective assessment of the task that semiconductor workers performed should be conducted to determine not only the effect of a particular job on the development of adverse health effects including mortality or cancer incidence, but also to adjust for the healthy worker effect. In order to identify specific hazardous agents that may cause adverse health effects, past exposure to a specific agent or agent matrices should also be assessed.

• 한국CDE학회논문집
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• 제9권1호
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• pp.51-61
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• 2004

Mechanical parts are often grouped into part families based on the similarity of their shapes, to support efficient manufacturing process planning and design modification. The 2-part sequence papers present similarity assessment techniques to support part family classification for machined parts. These exploit the multiple feature decompositions obtained by the feature recognition method using convex decomposition. Convex decomposition provides a hierarchical volumetric representation of a part, organized in an outside-in hierarchy. It provides local accessibility directions, which supports abstract and qualitative similarity assessment. It is converted to a Form Feature Decomposition (FFD), which represents a part using form features intrinsic to the shape of the part. This supports abstract and qualitative similarity assessment using positive feature volumes.. FFD is converted to Negative Feature Decomposition (NFD), which represents a part as a base component and negative machining features. This supports a detailed, quantitative similarity assessment technique that measures the similarity between machined parts and associated machining processes implied by two parts' NFDs. Features of the NFD are organized into branch groups to capture the NFD hierarchy and feature interrelations. Branch groups of two parts' NFDs are matched to obtain pairs, and then features within each pair of branch groups are compared, exploiting feature type, size, machining direction, and other information relevant to machining processes. This paper, the second one of the two companion papers, describes the similarity assessment method using NFD.

• 한국CDE학회논문집
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• 제9권1호
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• pp.44-50
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• 2004

Mechanical parts are often grouped into part families based on the similarity of their shapes, to support efficient manufacturing process planning and design modification. The 2-part sequence papers present similarity assessment techniques to support part family classification for machined parts. These exploit the multiple feature decompositions obtained by the feature recognition method using convex decomposition. Convex decomposition provides a hierarchical volumetric representation of a part, organized in an outside-in hierarchy. It provides local accessibility directions, which supports abstract and qualitative similarity assessment. It is converted to a Form Feature Decomposition (FFD), which represents a part using form features intrinsic to the shape of the part. This supports abstract and qualitative similarity assessment using positive feature volumes. FFD is converted to Negative Feature Decomposition (NFD), which represents a part as a base component and negative machining features. This supports a detailed, quantitative similarity assessment technique that measures the similarity between machined parts and associated machining processes implied by two parts' NFDs. Features of the NFD are organized into branch groups to capture the NFD hierarchy and feature interrelations. Branch groups of two parts' NFDs are matched to obtain pairs, and then features within each pair of branch groups are compared, exploiting feature type, size, machining direction, and other information relevant to machining processes. This paper, the first one of the two companion papers, describes the similarity assessment methods using convex decomposition and FFD.

• 품질경영학회지
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• 제42권1호
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• pp.111-127
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• 2014

Purpose: Simple part or equipment is necessary TRA(Technology Readiness Assessment) or MRA(Manufacturing Readiness Assessment). But sole maturity like TRA, MRA has limit complex systems or SoS(System of System). Especially complex weapon system need from the System Maturity Point of view. This research shows necessity of SRA(System Readiness Assessment). Methods: In case of complex systems, it is essential to SRA(System Readiness Assessment). For the purpose of calculating SRL(System Readiness Level), TRL and IRL must be calculated. And then SRL can obtain know from equation of TRL and IRL. To prove SRA effectiveness, it is calculated SRL of JTDLS(Joint Tactical DataLink System) programs. Results: SRA procedure is proposed and case study shows as examples of JTDLS programs. Although result of TRA is TRL6, result of SRA is not 0.6. From this research, we can know necessity of SRA. Especially complex systems or SoS(System of System) is essential to SRA. Conclusion: SRA(System Readiness Assessment) is required to overcome limitation of sole maturity and to achieve a successful acquisition of high quality weapon system. This research intended to suggest SRA procedure and case study in complex defense system.

• 한국산업보건학회지
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• 제22권1호
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• pp.9-19
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• 2012

Objectives: The aim of this study is to critically review the exposure surrogates and estimates used to associate health effects in wafer fabrication workers such as spontaneous abortion and cancer, as well as to identify the limitations of retrospective exposure assessment methods Methods: Epidemiologic and exposure-assessment studies of wafer fabrication operations in the semiconductor industry were collected. Retrospective exposure-assessment methods used in cancer risk and mortality and reproductive toxicity were reviewed. Results: Eight epidemiologic papers and two reports compared cancer risk among workers in wafer fabrication facilities in the semiconductor industry with the risk of the general population. Exposure surrogates used in those cancer studies were fabrication(vs. non-fabrication), employment duration, manufacturing eras, job title (operator vs. maintenance worker) and qualitative classifications of agents without assessing specific agent or job-specific exposure. In contrast, specific operation, job title and agents were used to classify the exposure of fabrication workers, contributing to finding a significant association with spontaneous abortion (SAB). Conclusion: Further epidemiologic studies of fabrication workers using more refined exposure assessment methods are warranted in order to examine the associations between fabrication work, environment, and specific agents with cancer risk or mortality as used in SAB epidemiologic studies.