• 한국시스템다이내믹스연구
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• 제16권3호
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• pp.5-29
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• 2015

The importance of the concept of safety culture has increased in the security of high-risk facility after Chernobyl accident in 1986. This paper elaborated the concept of safety culture and its main factors by Causal Loop Diagram. Due to the decline of safety culture, the occurrence of incidents and accidents require more and more corrective actions to the members of high-risk facilities and thereby increasing their workloads. Employees who must complete the task within the given time have to have time pressures and don't comply with the rules and procedures. Also, a schedule pressure is a big stress for employees, causing mistakes in precision work. In order to improve these problems, CLD of the safety culture in this paper suggests hiring more workers, re-allocation of given workloads and strengthen the learning, communication capabilities and safety leadership. In addition, the two real accident cases were analyzed to test the feasibility of the System Dynamic simulation model through the process of structuring the fault trees on the stationary black out accident in Kori unit 1 in South Korea and Kleen Energy power station explosion in US. The simulation results show that the various safety factors cause the serious accident combined with mechanical failure and safety culture will reduce the possibility of the accidents in these high-risk organizations. This simulation model can contribute to analyzing the impact of the organizational and human factors of safety culture and can provide the alternatives in high-risk facilities.

• 한국건축시공학회지
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• 제20권4호
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• pp.347-355
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• 2020

베트남의 경제 성장률과 도시인구는 꾸준히 증가함에 따라 베트남의 인프라 개발 건설 시장 규모는 더욱 커질 전망이다. 그러나 인프라 개발을 위한 베트남 정부는 재정 및 행정 능력의 한계로 이러한 문제를 해결하기 위한 방안으로 PPP를 채택하고 있다. PPP는 10년 이상 지속되는 장기 사업으로 사업 실패 시 장기적 큰 피해가 될 수 있어 위험관리가 매우 중요하다. 본 연구에서는 리스크 관리에 대한 리스크 요인의 영향과 관리정도 분석에 SOM분석을 제안한다. SOM분석 방법은 시각화 분석으로, 각 리스크 요인의 색상 패턴을 통해 상관 분석이 가능하다. 본 연구는 SOM을 활용하여 베트남 PPP 사업의 위험요인의 우선순위를 결정하고자 한다.

• 한국건설관리학회논문집
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• 제13권1호
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• pp.87-94
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• 2012

공동주택 재건축사업은 주거환경개선 및 신규 주택공급이라는 도시 계획적 순기능을 가지고 있지만, 원주민의 재정착 실패 및 소득 재분배 실패, 부동산투기, 주택가격의 급상승, 사업주체간의 갈등, 제도 미비 등 복합적인 요인에 의하여 사업 의도가 왜곡되고 재건축사업의 추진이 원활히 진행되지 못하고 있는 실정이다. 재건축사업 주체간의 갈등은 사소한 갈등이 확산되어 분쟁과 소송으로 이어지며, 그 결과 재건축사업이 원활히 추진되지 못하게 되어 사업기간과 비용을 증가시키거나 중단되는 경우가 발생하게 된다. 본 논문은 재건축사업의 역기능 중 사업주체간의 갈등을 예방하고 해결하기 위한 노력으로 재건축사업 추진과정을 중심으로 갈등지수를 산정하고 갈등지수를 이용하여 재건축사업의 기간과 비용을 예측하고자 한다. 갈등지수는 재건축사업의 주체간의 갈등요인을 중심으로 신정하며, 갈등지수를 포함한 여러 가지 독립변수를 이용하여 재건축사업의 기간과 비용을 예측한다. 또한 갈등지수의 산정과 사업기간 및 비용 예측을 통하여 사업주체간의 분쟁과 경제적 손실을 최소화 하고 성공적인 재건축사업의 추진에 기여할 수 있다.

• Tuberculosis and Respiratory Diseases
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• 제73권2호
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• pp.100-106
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• 2012

Background: There are a plethora of literatures showing that high-intensity intensive care unit (ICU) physician staffing is associated with reduced ICU mortality. However, it is not widely used in ICUs because of limited budgets and resources. We created a critical care team (CCT) to improve outcomes in an open general ICU and evaluated its effectiveness based on patients' outcomes. Methods: We conducted this prospective, observational study in an open, general ICU setting, during a period ranging from March of 2009 to February of 2010. The CCT consisted of five teaching staffs. It provided rapid medical services within three hours after calls or consultation. Results: We analyzed the data of 830 patients (157 patients of the CCT group and 673 patients of the non-CCT one). Patients of the CCT group presented more serious conditions than those of the non-CCT group (acute physiologic and chronic health evaluation II [APACHE II] 20.2 vs. 15.8, p<0.001; sequential organ failure assessment [SOFA] 5.5 vs. 4.6, p=0.003). The CCT group also had significantly more patients on mechanical ventilation than those in the non-CCT group (45.9% vs. 23.9%, p<0.001). Success rate of weaning was significantly higher in the CCT group than that of the non-CCT group (61.1% vs. 44.7%, p=0.021). On a multivariate logistic regression analysis, the increased ICU mortality was associated with the older age, non-CCT, higher APACHE II score, higher SOFA score and mechanical ventilation (p<0.05). Conclusion: Although the CCT did not provide full-time services in an open general ICU setting, it might be associated with a reduced ICU mortality. This is particularly the case with patients on mechanical ventilation.

• Geomechanics and Engineering
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• 제20권2호
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• pp.87-101
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• 2020

The construction of combined pile-raft foundations is considered as the main option in designing foundations in high-rise buildings, especially in soils close to the ground surface which do not have sufficient bearing capacity to withstand building loads. This paper deals with the geotechnical report of the Northern Fereshteh area of Tabriz, Iran, and compares the characteristics of the single pile foundation with the two foundations of pile group and geogrid. Besides, we investigate the effects of five principal parameters including pile diameter and length, the number of geogrid layers, the depth of groundwater level, and pore water pressure on vertical consolidation settlement and pore water pressure changes over a year. This study assessed the mechanism of the failure of the soil under the foundation using numerical analysis as well. Numerical analysis was performed using the two-dimensional finite element PLAXIS software. The results of fifty-four models indicate that the diameter of the pile tip, either as a pile group or as a single pile, did not have a significant effect on the reduction of the consolidation settlement in the soil in the Northern Fereshteh Street region. The optimum length for the pile in the Northern Fereshteh area is 12 meters, which is economically feasible. In addition, the construction of four-layered ten-meter-long geogrids at intervals of 1 meter beneath the deep foundation had a significant preventive impact on the consolidation settlement in clayey soils.

• Nuclear Engineering and Technology
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• 제45권5호
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• pp.625-636
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• 2013

Pressing demands of economic competitiveness, the need for large-scale deployment, minimizing the need of human intervention, and experience from the past events and incidents at operating reactors have guided the evolution and innovations in reactor technologies. Indian innovative reactor 'AHWR' is a pressure-tube type natural circulation based boiling water reactor that is designed to meet such requirements, which essentially reflect the needs of next generation reactors. The reactor employs various passive features to prevent and mitigate accidental conditions, like a slightly negative void reactivity coefficient, passive poison injection to scram the reactor in event of failure of the wired shutdown systems, a large elevated pool of water as a heat sink inside the containment, passive decay heat removal based on natural circulation and passive valves, passive ECC injection, etc. It is designed to meet the fundamental safety requirements of safe shutdown, safe decay heat removal and confinement of activity with no impact in public domain, and hence, no need for emergency planning under all conceivable scenarios. This paper examines the role of the various passive safety systems in prevention and mitigation of severe plant conditions that may arise in event of multiple failures. For the purpose of demonstration of the effectiveness of its passive features, postulated scenarios on the lines of three major severe accidents in the history of nuclear power reactors are considered, namely; the Three Mile Island (TMI), Chernobyl and Fukushima accidents. Severe plant conditions along the lines of these scenarios are postulated to the extent conceivable in the reactor under consideration and analyzed using best estimate system thermal-hydraulics code RELAP5/Mod3.2. It is found that the various passive systems incorporated enable the reactor to tolerate the postulated accident conditions without causing severe plant conditions and core degradation.

• 대한조선학회논문집
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• 제57권4호
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• pp.213-220
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• 2020

In the present paper, implosion responses of two adjacent cylindrical tubes under external hydrostatic pressure were experimentally investigated. The cylinder models were fabricated of aluminium alloy 6061-T6 commercial tubes. In the experiment, a pair of two-cylinders were placed inside of a support frame in a medium-size pressure chamber, whose design pressure was 6.0MPa. The distance between the two-cylinders was 30 millimeter measured from outer shell at the mid-length. The implosion tests were performed with water and compressed nitrogen gas as the pressurizing media. The ambient static pressure of the chamber and local dynamic pressure near the two-imploded models were measured simultaneously. It was found that the energy released during an implosion from the first, weaker cylinder triggered the instability of the second, stronger cylinders. In other words, the resulting shock wave of the first implosive impact from the weaker cylinder could cause the premature failure of the neighboring stronger cylinders. The non-contact implosion phenomena from the two-cylindrical tube were clearly observed.

• 기술혁신학회지
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• 제13권2호
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• pp.282-309
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• 2010

최근 기술무역에 의한 기술도입은 글로벌 시대에서 핵심적인 기술혁신전략이라고 할 수 있으며, 기술도입의 현황분석을 통해 국가의 기술정책을 수립하는 것은 국가경쟁력 확보에 매우 중요한 요소라고 볼 수 있다. 그러나 기술무역에 대한 연구들의 대부분은 기술무역의 특성파악과 거시적인 현황 및 파급 효과분석에만 초점을 맞추고 있어, 실질적으로 국가의 정책을 수립하는 데에는 이론적/실무적 배경을 제시하지 못하고 있는 실정이다. 따라서 본 연구에서는 한국은행의 '기술도입대가 지급현황' 데이터를 활용하여 지식경제부의 통합기술청사진에서 사전에 정의된 31개 중점기술분야에 대해 기술집중도, 기업집중도, 국가집중도를 분석하고, 기술별 거래되는 기술유형과 기술도입거래대가 유형을 분석하였다. 이를 통해, 기술분야별로 기술거래가 특정 하위기술, 기업, 국가에 집중되는 정도를 분석하고, 기술거래유형의 특성을 분석하여 국내산업의 기술도입 특성을 도출하였다. 본 연구의 결과는 국가에서 기술의 수출 및 수입에 관련된 기술정책을 수립하는 영역에서 뿐만 아니라 국내산업의 기술혁신 특성을 분석하기 위한 중요한 자료로 활용될 수 있을 것이다.

• 유통과학연구
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• 제16권8호
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• pp.69-77
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• 2018

Purpose - With growing competition in the service distribution industry, the importance of managing customer complaints has increased. If firms handle customer complaints effectively, they can strengthen customer loyalty and repurchase intention. Many studies have focused on customers expressing complaints, yet research on silent customers is scant. This study focuses on two types of complainers and non-complainers. In other words, this study is to examine the value of voice complaint intention and no-action intention. This study also investigates how perceptual and relational factors affect complaint intention. Research design, data, and methodology - This study was carried out using the survey with undergraduate students who have faced a service failure in a retail store(fast foods, electronics, apparel). And if such complaint were to occur again, respondents were asked about any possible action they would take. 300 questionnaires were distributed and a total of 279 respondents provided complete and usable data. The sample consisted of 158 males(56.6%) and 121 females(43.4%). The structural equation modeling analysis was used for the hypothesis test. Results - The results are as follows. First, attitude toward complaining, likelihood of successful complaint, and ease of complaint were positively related to voice complaint intention. Second, attitude toward complaining, likelihood of successful complaint, and ease of complaint were negatively related to no-action intention. Third, commitment was positively related to voice complaint intention but didn't have a significant negative impact on no action. Forth, voice complaint behavior reduced switching intention and no-action intention enhanced switching intention. Conclusions - The findings of this study confirm the value of complaint behavior and show voice complaint intention and no-action intention should be managed differently. Voice complaint intention is evaluated positively because it reflects customers' concerns about the company, while no-action intention is evaluated negatively. Attitude toward complaing is the most effective in increasing voice complaint intention and likelihood of successful complaint is a major factor in reducing no-action intention. Also, in explaining switching intention, voice complaint intention plays a more important role than no-action intention.

• 한국구조물진단유지관리공학회 논문집
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• 제24권4호
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• pp.91-99
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• 2020

콘크리트용 앵커볼트는 콘크리트 구조물에 대한 비구조요소의 정착에 주로 사용되고 있으며, 시공성의 이점에 따라 후설치앵커가 주로 사용되고 있다. 앵커의 저항 성능과 관련하여 콘크리트 쪼개짐 영향을 최소화하기 위한 위험 연단거리가 제시되고 있지만 실제 앵커의 경우 이상적인 연단거리를 확보하기 어렵다. 즉, 인장 하중에 따라 발생 가능한 콘크리트 쪼개짐 등 복합적인 요소가 포함된 앵커의 저항 성능과 인장 거동 특성을 파악하기 위함이 본 연구의 목적이다. 표준시험방법을 바탕으로 인장실험을 진행하고 도출된 하중-변위 결과 및 파괴 형상을 분석하였다. 위험 연단거리가 확보되지 않은 앵커의 경우 인장력에 의해 콘크리트 쪼갬 파괴가 동반된 파괴 모드가 도출되고 저항 특성은 강성 구간으로 분류된다. 또한, 실험체 구성 요소를 바탕으로 비선형 유한요소모델을 구성하였으며, 앵커 거동을 모사하기 위해 구속 조건 및 연결요소 조건에 따른 경계조건별 변수 해석을 수행하였다. 이에 따라 도출된 해석 결과는 콘크리트 내부 파괴 영향성 및 실제 앵커의 거동을 바탕으로 검증하여 범용구조해석 프로그램 내 경계조건을 통한 저항 메커니즘 적용이 가능한 것으로 판단된다.