시뮬레이션을 이용한 정비 프로세스 평가 모형 연구

권혁상,이상진,정성태 한국방위산업학회 2014 韓國防衛産業學會誌 Vol.21 No.4

본 논문의 목적은 군 정비 프로세스를 평가하기 위해 장비 운용가용도를 핵심 성과지표로 한 평가 모형을 구축하고, 정비 프로세스 향상에 미치는 영향요인을 파악하는 것이다. 군의 전투준비태세 완비 여부는 장비 운용가용도와 직결되기 때문에 목표 운용가용도를 유지하기 위한 효율적인 정비활동이 요구된다. 따라서 장비 운용개념, 정비 및 수리부속 정책, 장비 운용가용도의 직접적 원인이 되는 장비 불가동시간을 복합적으로 고려하여 일반화된 정비 프로세스를 모델링하였다. 또한, 시뮬레이션을 이용하여 일반화된 정비 프로세스에 대한 평가 모형을 구축한 후, 운용가용도를 측정하고 운용가용도 변화의 영향요인을 분석하였다. 본 연구는 정비 프로세스를 일반화하고 평가 모형을 구축함으로써, 이를 기반으로 정비 프로세스 향상 방안을 도출할 수 있다는데 의의가 있다. The purposes of this study are twofold: to construct a generalized model for assessing the operational availability and the target availability achievement rate of military maintenance processes, and to identify the major factors affecting the operational availability of maintenance processes. Downtime has a direct impact on operational availability. Downtime is divided into three categories: ADT (Administrative Delay Time), LDT (Logistics Delay Time), and maintenance time due to the maintenance capability restrictions. Based on the analyses of such downtimes and maintenance policies and regulations, this paper proposes a maintenance process model from bases to depots. For the assessment of maintenance processes, a simulation method is adopted. In the empirical study, a UH-60 helicopter was chosen because it is operated in every military service. Using such simulation model, sensitivity analysis was performed on the operational availability depending on the changes in the maintenance factors: capability, spare parts stock levels, order period, and transport time. The operational availability changes depending on the aforementioned factors. In this study, the major factors influencing the improvement of the operational availability were identified, and the maintenance capability was determined to be the most important of such factors. Maintenance systems vary depending on the military service and weapon system. The results of this study can be applied to weapon systems to identify the factors that restrict the improvement of the operational availability.

광양항 컨테이너터미널 통합 결정요인에 관한 연구

박여진,심민섭,김율성,남형식 한국해운물류학회 2022 해운물류연구 Vol.38 No.2

In the recent rapidly changing period, polarization for shipping and port companies, especially those operating port terminals, is maximizing. In particular, the Gwangyang Port container terminal operator is being considered for integration between terminal operators due to operational difficulties such as low productivity, low handling charge, and continuous deficit operation. In this study, analyzing determinants that should be considered when integrating Gwangyang operators in the future. In particular, it reflects changes in the environment of Gwangyang Port and existing studies. In addition, based on the determinants analyzed in this way, the Gwangyang Port integration scenario was derived and the importance of each scenario was analyzed. This study is meaningful in that it reflects the recently changed environment of Gwangyang Port and analyzes factors to be considered in future integration rather than the necessity and effect of integration.

UV/TiO₂공정의 최적 운전조건 결정

강성환,전은주,임재명 江原大學校 附設 環境硏究所 1999 環境硏究 Vol.16 No.-

This research aims to analyze influencing factors and determine optimal operation conditions on UV/TiO₂process for piggery wastewater treatment. Relation between influencing factors and optimum operating conditions were determined by Response Surface Methodology, which was mathematical and statistical method for the modeling of process. The removal rates of TCOD and color increased with increasing temperature, dissolved oxygen concentration, and pH, but decreased with increasing initial TCOD concentration. As the result of RSM, optimum operating conditions TCOD and color removal were temperature of 35~43 ℃. DO concentration of 503~6.3 ㎎/L, less than 110 ㎎/L of initial TCOD concentration, and more than 6.3 of pH. According to RSM modeling, effect of initial TCOD concentration for TCOD and color removal was greatest, and secondly, temperature and DO concentration were influential, and the effect of pH and interaction between influencing factors were negligible. As the result of the comparisons of experimental data with modeling data of RSM, the relationship was very high. 본 연구의 목적은 UV/TiO₂공정에서 돈사폐수의 TCOD와 색도 제거를 위한 영향인자 해석과 최적 운전조건을 반응표면분석이라는 통계적 기법을 통해 도출하는 것이다. 반응표면 분석결과 TCOD와 색도의 제거율은 온도, 용존산소 농도, 그리고 pH가 증가할수록 높아졌으며, 유입 TCOD 농도가 증가할수록 낮아지는 것으로 나타났다. TCOD와 색도 제거율에 미치는 영향은 유입 TCOD 농도가 가장 크고, 그 다음은 온도, 용존산소 농도의 순으로 나타났으며, pH 및 영향인자 상호작용에 의한 영향은 미미한 것으로 나타났다. 또한 TCOD와 색도 제거를 위한 최적 운전조건은 온도 35~43 ℃, 요온산소 농도 5.3~6.3 ㎎/L, 유입 TCOD 농도 110 ㎎/L 이하, 그리고 pH 6.3 이상으로 나타났다. 마지막으로 방응표면분석에 의한 2차 회귀모형을 검증한 결과 모형의 유의성이 매우 높은 것으로 나타났다.

해외 LNG 플랜트 운영관리단계의 정성적 위험요인 분석

지덕근,박문선,김용수,Ji, Deak-Keun,Park, Moon-Sun,Kim, Yong-Su 大韓建築學會 2014 大韓建築學會論文集 : 構造系 Vol.30 No.8

The purpose of this study is to analyze qualitative risk factors that are considered in operation and management phases of overseas LNG plant. For this purpose, the study investigated risk factors of similar projects. Based on these results, risk factors of overseas LNG plant are derived and qualitative risk factors are classified from interview with experts. Qualitative risk factors that have been classified, are analyzed priority and relative importance by using AHP method. The results of this study according to purpose and method are as follows: 1)Forty-two risk factors, from 125 risk factors of similar projects being investigated, on LNG plant operation and management phases were derived. Risk factors were separated by transportation, sales, maintenance and management, and then 20 qualitative risk factors were derived by survey of experts. The results of relative importance analysis by using AHP method based on qualitative risk factors are as follows: Relative importance of "LNG production which does not meet quality contract(M-12)" was analyzed as the most highly risky factor. "Cancel a license contract of core technology(M-07)", "Insufficient review of local relevant laws(M-08)", "Occurred defects of equipment due to insufficient design(R-08)" have been analyzed in order of importance.

해외 LNG 플랜트 운영관리단계의 정성적 위험요인 분석

지덕근(Ji, Deak-Keun),박문선(Park, Moon-Sun),김용수(Kim, Yong-Su) 대한건축학회 2014 大韓建築學會論文集 : 構造系 Vol.30 No.8

The purpose of this study is to analyze qualitative risk factors that are considered in operation and management phases of overseas LNG plant. For this purpose, the study investigated risk factors of similar projects. Based on these results, risk factors of overseas LNG plant are derived and qualitative risk factors are classified from interview with experts. Qualitative risk factors that have been classified, are analyzed priority and relative importance by using AHP method. The results of this study according to purpose and method are as follows: 1)Forty-two risk factors, from 125 risk factors of similar projects being investigated, on LNG plant operation and management phases were derived. Risk factors were separated by transportation, sales, maintenance and management, and then 20 qualitative risk factors were derived by survey of experts. The results of relative importance analysis by using AHP method based on qualitative risk factors are as follows: Relative importance of “LNG production which does not meet quality contract(M-12)” was analyzed as the most highly risky factor. “Cancel a license contract of core technology(M-07)”, “Insufficient review of local relevant laws(M-08)”, “Occurred defects of equipment due to insufficient design(R-08)” have been analyzed in order of importance.

AHP 기법을 이용한 부유식 해상 풍력 단지 내 근해자망어업 위험 요인 분석

안종갑,박유진,정유진,안영수 한국수산해양기술학회 2023 수산해양기술연구 Vol.59 No.4

본 연구에서는 AHP(Analytic Hierarchy Process) 기법을 사용하여 부유식 해상풍력단지(floating Offshore Wind Farms, floating OWF) 내에서 자망어업 시 예상되는 위험 요인에 대한 위험도와 어업 가능성에 대해 분석하였다. 이를 위해 부유식 해상풍력단지 내에서 자망어업 시 발생할 수 있는 위험을 충돌, 걸림, 감김으로 정의하였다. 그리고 이러한 위험을 발생시키는 위험 요인들을 3개의 상위 위험 요인과 10개의 하위 위험 요인으로 분류하고, 부유식 해상풍력단지 내에서 가능한 자망어업의 대안을 3개로 분류한 후 계층도를 수립하였다. 마지막으로 국내의 수산·해양 관련 전문가를 대상으로 설문조사를 수행하고 응답 결과를 분석하였다. 분석 결과, 상위 위험 요인 중에서는 어구 부설 시의 위험도가 가장 큰 것으로 나타났다. 각 상위 위험에 대한 하위 요인의 위험도는 각각 접안(계류) 시, 최종 양망 시점 시, 저층 그물 부설 시의 위험도가 가장 큰 것으로 나타났다. 대안들을 기준으로 통합 위험도 순위의 평균은 항해/조업의 전면 허용이 위험도가 가장 높은 것으로 나타났다. 통합 위험도의 최종순위 분석 결과, 저층 그물이 부설된 곳에서 항해/조업 전면 허용 순위가 1위로 나타난 반면, 단지 내 선박 이동 시 항해/조업 금지는 통합 위험도 순위가 가장 낮은 30위로 분석되었다.이를 통해 부유식 해상풍력단지 내에서의 자망어업 가능성은 높지 않을 것으로 분석한 반면, 선박의 항해는 가능할 것으로 분석하였다. In this study, the AHP (analytic hierarchy process) technique was used to analyze the risk of expected risk factors and fishing possibilities during gillnet fishing within the floating offshore wind farms (floating OWF). For this purpose, the risks that may occur during gillnet fishing within the floating offshore wind farms were defined as collisions, entanglements, and snags. In addition, the risk factors that cause these risks were classified into three upper risk factors and ten sub risk factors, and the three alternatives to gillnet fishing available within the floating OWF were classified and a hierarchy was established. Lastly, a survey was conducted targeting fisheries and marine experts and the response results were analyzed. As a result of the analysis, among the top risk factors, the risk was the greatest when laying fishing gear. The risk of the sub factors for each upper risk was found to be the highest at the berthing (mooring), the final hauling of fishing net, and the laying of the bottom layer net. Based on the alternatives, the average of the integrated risk rankings showed that allowing full navigation/fisheries had the highest risk. As a result of the final ranking analysis of the integrated risk, the overall ranking of allowing navigation/fisheries in areas where bottom layer nets were laid was ranked the first when moving vessels within the floating OWF was analyzed as the lowest integrated risk ranking of the 30th at the ban on navigation/fisheries. Through this, navigation was analyzed to be possible while it was analyzed that the possibility of gillnet fishing within the floating OWF was not high.

Evaluation of Delay Factors on Dry Bulk Cargo Operation in Malaysia: A Case Study of Kemaman Port

Noorul Shaiful Fitri ABDUL RAHMAN,Mohammad Khairuddin OTHMAN,Izzat Amir SANUSI,Alisha ISMAIL 한국해운물류학회 2019 The Asian journal of shipping and Logistics Vol.35 No.3

There are various types of delay factors that could affect the efficiency and effectiveness of the dry bulk cargo operation, especially in port. Hence, it raises the concerns of the stakeholders, as some of them can significantly affect their actual transport plans and cost them extra money to handle the cargo. Due to uncertainty of the most significant delay factor in some Malaysia’s dry bulk ports, therefore, this study aims to evaluate the most significant delay factors that causing delays in dry bulk cargo operation by using the analytical hierarchy process (AHP) method. This study found that the factor of ‘Miscellaneous’ is the most significant factor that contributed to the most of delay creations in dry bulk cargo operation in Kemaman port. Meanwhile, sub-criterion of ‘Foul weather and tide prediction’ is selected as the most significant sub-cause of delay creation in similar port. This study contributes the practical technique and valuable findings to the port and its stakeholders, where it may alert the them to measure the factors that affect their operational performance and business. Also, it introduces the usage of practical and systematical analysis technique for assisting the seaport operator or interested parties in analyzing the potential contributors of a condition in the port settings.

블루수소 생산을 위한 이산화탄소 포집용 2단 분리막 공정 최적화 연구

이정현,박진우,이준협,허소연,여정구,심재훈,임진혁,이충섭,김진국 한국막학회 2023 멤브레인 Vol.33 No.6

본 연구에서는 중공사형 이산화탄소 분리막 모듈을 사용하여 수소개질기 배가스로부터 이산화탄소 포집을 목적으로 한 분리막 공정 최적화 연구를 진행하였다. 랩스케일의 소형 분리막 모듈을 사용하여 혼합기체를 대상으로 이산화탄소순도 90% 및 회수율 90%을 달성하는 2단 공정 조건을 도출하였다. 막 면적이 정해진 모듈의 분리막 공정에서는 스테이지-컷,주입부 및 투과부 압력에 따라서 포집 순도 및 회수율이 모두 다르게 나타나기 때문에 운전 조건에 대한 최적화가 필수적이다. 본 연구에서는 다양한 운전 조건에서 1단 분리막에서 보이는 공정 포집 효율의 한계를 확인하고, 높은 순도와 회수율을동시에 달성하기 위한 2단 회수 공정을 최적화하였다. The membrane separation process for carbon dioxide capture from hydrogen reformer exhaust gas has beendeveloped. Using a commercial membrane module, a multi-stage process was developed to achieve 90% of carbon dioxidepurity and 90% of recovery rate for ternary mixed gas. Even if a membrane module with being well-known properties suchas material selectivity and permeability, the process performance of purity and recovery widely varies depending on thestage-cut, the pressure at feed and permeate side. In this study, we verify the limits of capture efficiency at single-stagemembrane process under various operating conditions and optimized the two-stage recovery process to simultaneously achievehigh purity and recovery rate.

도시가스 사업장 근로자에 대한 안전커뮤니케이션, 안전침묵 동기와 침묵행동 사이의 영향관계

김혜진,박달재 한국가스학회 2019 한국가스학회지 Vol.23 No.2

One of the key factors of a safe workplace is to communicate with the workers about safety. For this, natural gas workplace is developing and operating related programs or communication activities. But, if there are silence behavior of the workers on the safety issues in this process, no positive outcomes could be expected for the workplace. The purpose of this study is to examine how safety silence motives, silence behavior, and safety communication influence each other. A total of 233 questionnaires based on the workers of natural gas workplace (in Seoul and Gyeonggi) were analyzed. The confidence analysis is to check consistency of the questions, analysis of the correlations between factors, and regression analysis to verify the hypotheses. As a result, the safety silence motives affected safety communication more seriously than the silence behavior did. Safety communication influenced safety silence motives more significantly than the silence behavior. The safety silence motives can be one of the reasons for safety communication to fail, and it was confirmed that a good safety communication does not necessary mean that there is no safety silence motivation. Based on such results, it is expected that improving and developing the safety communication activities of the workplace, it would improve safety in workplace in general. 안전한 사업장을 만들기 위한 핵심 요소 중 하나는 근로자들이 안전 문제에 대해 활발하게 소통하는 것이다. 이를 위해 도시가스 사업장에서는 관련 프로그램이나 커뮤니케이션 활동 등을 개발 및 운영하는데 노력하고 있다. 그러나 이러한 노력의 과정에서 안전 문제에 근로자들의 침묵행동이 발생할 경우, 사업장 안전관리 향상에 긍정적 변화를 기대하기 어려울 것이다. 이에 본 연구에서는 ○○ 도시가스 사업장(서울 및 경기지역) 근로자 233명을 대상으로 안전침묵 동기, 침묵행동과 안전커뮤니케이션 사이에 영향관계를 조사하고자 관련 설문지를 개발하여 분석하였다. 설문 문항의 일관성을 확인하고자 신뢰도 분석, 각 요인의 영향 변인 간 상관분석 및 가설 검증에 대한 회귀분석을 실시하였다. 연구 결과, 안전침묵 동기가 침묵행동보다 안전커뮤니케이션에 그리고 안전커뮤니케이션이침묵행동보다 안전침묵 동기에 높은 영향을 미쳤다. 이러한 결과는 안전침묵 동기가 안전커뮤니케이션이 잘 안 되는 이유 중 하나라 해석할 수 있다. 또한, 안전커뮤니케이션이 잘 된다고 하여 안전침묵 동기가 존재하지 않는 것이아니라는 것도 확인되었다. 이러한 결과를 바탕으로 사업장의 안전 관련 커뮤니케이션 활동을 개선하고, 개발한다면 사업장 내 안전을 전체적으로 향상시키는 데 도움이 될 것으로 기대된다.

Comparison of different fluid dynamics in activated sludge system for the treatment of a stimulated milk processing wastewater: Process analysis and optimization

Ali Akbar Zinatizadeh Lorestani,Hojjatollah Bashiri,Azar Asadi,Hossein Bonakdari 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.10

Wastewater from the milk industry usually undergoes activated sludge ahead of refining treatments, final discharge or reuse. To identify the most effective bioreactor hydraulic regime for the secondary treatment of wastewater resulting from the milk industry in an activated sludge system, two lab-scale activated sludge systems characterized by a different configuration and fluid dynamics (i.e., a compartmentalized activated sludge (CAS) with plug flow regime and a complete mixed activated sludge (AS)) were operated in parallel, inoculated with the same microbial consortium and fed with identical streams of a stimulated dairy wastewater. The effect of three process and operational variables--influent chemical oxygen demand (COD) concentration, sludge recycle ratio (R) and hydraulic retention time (HRT)--on the performance of the two systems were investigated. Experiments were conducted based on a central composite face-centered design (CCFD) and analyzed using response surface methodology (RSM). The region of exploration for treatment of the synthetic wastewater was taken as the area enclosed by the CODin (200, 1,000 mg/l), R (1, 5), and HRT (2, 5 h) boundaries. To evaluate the process, three parameters, COD removal efficiency (E), specific substrate utilization rate (U), and sludge volume index (SVI), were measured and calculated over the course of the experiments as the process responses. The change of the flow regime from complete-mix to plug flow resulted in considerable improvements in the COD removal efficiency of milk wastewater and sludge settling properties. SVI levels for CAS system (30-58 ml/g) were considerably smaller that for the AS system (50-145 ml/g). In addition, the biomass production yield could be reduced by about 10% compared to the AS system. The results indicated that for the wastewater, the design HRT of a CAS reactor could be shortened to 2-4 h.