• Journal of the Korea Society for Simulation
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• 제13권1호
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• pp.41-50
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• 2004

The purpose of this paper is to analyse the manager's policy to maximize the profit in a multiple-server queueing facility with a limited queue capacity. We assume that the level of advertizing effects on the arrival rate of customers to the facility. The model without ‘word of mouth effect’ is assumed that the arrival rate is independent on the qualify of service level. We estimate the service quality by the balking rate of customers from system. We extend this to the model with ‘word of mouth effect’. To achieve the maximum profit, the most important factor is the considerably high utilization of facility for both models. Given service rate, we should maintain an effective arrival rate to some extent. To this end, among the available options, an increase of advertizing effort is more desirable than reducing the fee if the service value of customers remains unchanged. We also investigate whether the variability of service time has a significant impact on determining the optimal policy. The cost of service variability is not so expensive as that in a single server model due to the reduced variability of service times in a multiple-server model.

• Korean Journal of Environmental Biology
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• 제22권3호
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• pp.369-375
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• 2004

This experiment was studied to obtain basic environmental effects and biological information on the early growth of larval mitten crab (Eriocheir sinensis). Mitten crabs were maintained for each larval stage with solutions containing 0.1, 0.2, and 0.3 ppm of cadmium (Cd) and mercury (Hg). The relationship between survival rate of mitten crabs and metal content in the growth chamber showed a positive correlations. However, it showed a significant difference in the 96 $hr- LC^{50}$ values of Cd and Hg for the E. sinensis larvae from the first zoea larva to juvenile. Hg was more toxic to E. sinensis larval than Cd. When Cd and Hg are released into the water, they enter E. sinensis larval and are biological magnified. These results of survival rate and bioaccumulation are very important when considering the survival of the mitten crab.

• Aerospace Engineering and Technology
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• 제7권1호
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• pp.236-244
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• 2008

The evolution and application of RFID technologies have been at the forefront of allowing aviation industries to improve the quality of aircraft maintenance and air cargo handling. However, safety problems in airplane operation are arising from the hazards of frequencies transmitted due to RFID systems. Though the intensities of frequencies back-scattered from the tags are very weak, some malfunctions are anticipated due to induction coupling on aircraft wiring. Therefore, safety assessment such as electromagnetic compatability should be accomplished upon aircraft critical and essential equipments before installations.

• Composites Research
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• 제22권6호
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• pp.52-62
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• 2009

This paper is for the state of the art of the lightweight protective clothing against the mine, and it covers the preliminary work focused on the appropriate protection, ballistics, convenience, and wearability. It is suggested that the lightweight protective clothing should be fabricated with the laminated materials of high strength woven and non-woven fabrics to reduce the weight and thickness, thus improving the wearability. And partial reinforcement of the protective clothing is necessary to prevent the mortal wound near the important parts of the body without disturbing the arbitrary activity. The composition of the protective clothing should be designed in consideration of easy putting-on and taking-off in addition to easy divesture, which require little motion of the body is in case of serious injury. Additionally, status of the practical technique for high performance and ultra-light hybrid armor material were also described.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제30권5A호
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• pp.417-424
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• 2010

The dynamic properties of laminated rubber bearings used as isolators in structures could be significantly deteriorated because of the change of microstructure in rubber caused by thermal aging. As a result, a catastrophic failure of bridges and buildings unexpectedly occurs when they are subjected to earthquake attack. Here, the dynamic properties of laminated rubber bearings before and after different of compression-shear loading and repeated cycles loadings, ultimated failure test with thermal aging were first measured and compared to each other. The experimental results, the effects of thermal aging on the shear stiffness, energy absorption, and equivalent damping coefficient of laminated rubber bearings are investigated. It is found that the deterioration of dynamic properties of laminated rubber bearings caused by thermal aging is significant and should be taken into account in designing rubber bearings.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제39권4호
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• pp.49-59
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• 2016

Naval combat system developed in-country is progressing at an alarming rate since 2000. ROK navy will be achieved all vessels that have combat system in the near future. The importance of System Engineering and Integrated Logistics Support based on reliability analysis is increasing. However, reliability analysis that everyone trusted and recognized is not enough and applied practically for development of Defense Acquisition Program. In particular, Existing Reliability Analysis is focusing on reliability index (Mean Time Between Failure (MTBF) etc.) for policy decision of defense improvement project. Most of the weapon system acquisition process applying in the exponential distribution simply persist unreality due to memoryless property. Critical failures are more important than simple faults to ship's operator. There are no confirmed cases of reliability analysis involved with critical failure that naval ship scheduler and operator concerned sensitively. Therefore, this study is focusing on Mean Time To Critical Failure (MTTCF), reliability on specific time and Operational Readiness Float (ORF) requirements related to critical failure of Patrol Killer Guided missile (PKG) combat system that is beginning of naval combat system developed in-country. Methods of analysis is applied parametric and non-parametric statistical techniques. It is compared to the estimates and proposed applications. The result of study shows that parametric and non-parametric estimators should be applied differently depending on purpose of utilization based on test of normality. For the first time, this study is offering Reliability of ROK Naval combat system to stakeholders involved with defense improvement project. Decision makers of defense improvement project have to active support and effort in this area for improvement of System Engineering.

• Journal of the Korean Society for Aviation and Aeronautics
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• 제2권
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• pp.139-182
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• 1994

조종사들은 비행시에 일상 생활 환경에서는 경험하지 못하는 여러가지 적대환경에 폭로된다. 이러한 환경에서는 인체의 평형기관은 실제와 일치하지 않는 정보를 제공해 주는 경우가 허다하다. 예를들면, 내이의 미로 전정기관이나 피하압력기관기 등은 항공기의 기동으로 발생하는 중력과 지구의 중력을 구별 하지 못하는 기능의 한계성때문에 계기비행하에서는 대개의 경우 공간정위상실, 즉 비행착각을 유발한다. 이 착각으로 인한 항공기 사고는 통계상에서 상당 부분이 치명사고로 나타나고 있는데, 이러한 사실은 비행착각현상이 비행안전에 극히 위험한 요소가 되고 있다는 것을 실증한다고 할 수 있다. 그러므로 조종사들은 비행시 공간정위 유지를 위한 철저한 대비가 있어야 한다. 공간정위 상실현상이 잘 발생하는 경우는 야간이나 기타 계기비행 환경에서 주위시각이 제약을 받을 때이다. 즉, 계기비행 환경에서의 편대비행시나 고기동시, 그리고 대조물이 모호한 야간의 활주로에서 이착륙할때 등을 들 수 있다. 비행시 공간정위 상실현상을 예방하기 위해서는 첫째로 이러한 유형의 사고분석자료를 토대로 하여 항공기의 설계단계에서부터 제작에 이르기까지 착각을 유발할 수 있는 구조적 요인을 제거해야 한다. 둘째로는 이러한 착각을 유발하지 않는 운항이나 기동방식을 택하여 비행임무를 수행토록 해야한다. 세째로 조종사들은 이러한 착각을 정상적인 인체의 반응에 의한 것이므로 자신에게도 당연히 일어난다는 사실을 용인해야 한다. 네째로 조종사들은 계기비행에 대한 구체적이고 실제적인 훈련을 통하여 계기비행 경험을 쌓아야 한다. 다음은 조종사들의 실제비행시 공간정위 상실현상에 봉착했을때의 처리요령이다. 첫째로 계기비행상황에서 자신의 감각과 계기가 일치하지 않을 때는 즉시 계기를 Cross Check하여 항공기의 자세나 기동형태를 정확하게 파악해야 한다. 둘째로 계기가 조종사의 의도대로 나타나도록 조작하고 이를 철저하게 의지하고 믿어야 한다. 세째로 자신의 감각과 계기가 일치할때까지 수평비행을 유지해야 한다. 그리고 마지막으로, 고성능 항공기가 계기비행중 저공에서 비행착각에 봉착하게 될때의 행동절차를 철저하게 숙지하고 있어야 한다.

• Proceedings of the KAIS Fall Conference
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• 한국산학기술학회 2009년도 추계학술발표논문집
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• pp.774-777
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• 2009

2001년 9 11 테러 이후 미국에서 탄저균을 이용한 생물테러가 발생한 이래 미국을 비롯한 여러 나라에서는 생물무기 및 생물테러에 대한 대응방안들이 준비되고 있다. 따라서 이런 대응방안과 더불어 생물무기를 쓰는 테러리스트의 행동과 위협에 대비를 할 필요가 있다. 생물테러 전염병은 치명률이 높고, 인간 상호간에 전염이 용이하며 치료하기가 어려우므로, 인명의 손실을 최소화하기 위해서는 보건의료기관 등에서 근무하는 보건의료인이 생물테러로 의심되는 병원체 및 전염병을 조기에 인지하는 것이 가장 중요하다. 따라서 보건분야 전문가들은 환자나 일반 대중, 그리고 다른 보건전문가들에게 생물무기와 생물테러에 의해 퍼질 가능성이 있는 질병들에 대해 신중하게 대응할 수 있는 방법들을 교육해야 한다. 질병이 발생했을 때 보건전문가들은 조사에 착수할 역학자들과 협조를 해야 하고, 임상 또는 연구소에 일하는 보건전문가들은 생물무기로 사용될 수 있는 병원체나 생물무기를 생산하는데 사용되는 시설에 접근하는 것을 제한하도록 도울 수 있다. 2005년 질병관리본부 생물테러대응팀에서는 의료인, 다중시설이용 근무자, 보건요원을 대상으로 생물테러 인식도를 조사한 바 있다. 조사결과, 의료인에 대한 생물테러 교육 및 교육훈련의 필요성에 대해 94.2%가 필요하다고 응답하였다. 이런 자료를 바탕으로 하여 국내에서도 생물테러교육의 필요성이 대두되기 시작하였다. 본 연구는 미국, 영국에서 진행되고 있는 생물테러 관련 교육에 대한 관련 자료와 사례를 문헌 분석을 통해 우리나라에 맞는 생물테러 교육에 대한 방향을 제시하고 문제중심학습모듈을 개발하고자 하는데 그 목적이 있다.

• Clinics in Shoulder and Elbow
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• 제10권1호
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• pp.136-139
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• 2007

Shoulder arthroscopic surgeries are an accepted technique for many shoulder disease and have many advantages over open surgeries. To date, shoulder arthroscopic surgery have been rare complications that compromise patient airway, caused by the leakage of irrigation fluid out of the shoulder joint space into the surrounding soft tissues and then the neck and the pharynx. This report presents a case of life-threatening airway obstruction due to extra-articular saline collection during arthroscopic rotator cuff repair. In concluding we should hourly check the patient's neck swelling undergoing shoulder arthroscopic surgery, because anesthetized patients cannot complain of the airway problem may progress until it becomes life-threatening.

• The Journal of Bigdata
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• 제2권1호
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• pp.17-26
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• 2017

The gradual desertification in Northeastern China brought about by the industrial development and global warming, has affected the Korean peninsula as evident by the ultrafine dust geographically and seasonally. People with severe respiratory problems, senior citizens and the infants are susceptible to the ill effects of fine dust which could prove fatal to them. Hence, we need to study the root cause of fine dust emergence and the correlation verification between fine dust and its side effects. This study firstly analyzed clean and contaminated areas classified by industrial elements. We utilized air, weather and industrial data in the area. Next, we detected a change of fine dust in terms of weather and climate. We analyzed correlation of air and weather by influence from domestic and neighboring country. The result indicated that China is the culprit of the emergence of fine dust predicament. Consequently, we can prove that fine dust ($PM_{10}$) and ultrafine dust ($PM_{2.5}$) could arise from geographical, seasonal, and pollutant elements. Therefore, we propose the optimum to make countermeasures about fine dust in terms of industry, topography, population and living residence.