• 대한교통학회지
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• 제25권6호
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• pp.129-140
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• 2007

대중교통 운행계획 수립과정은 이론적인 연구의 특성에 따라 설계, 운영, 그리고 평가 단계로 구분할 수 있다. 운영단계와 평가단계에서 이루어지는 연구들에 대해서는 비교적 체계적으로 정리된 연구와 보고서들이 있으나 설계단계에 관한 연구들은 체계적으로 정리된 적이 없다. 본 연구에서는 대중교통 시스템설계에 관한 기존의 연구들을 검토하여 체계적으로 정리하였다. 또한 해당 연구들의 모형 구조를 자세히 분석하여 이의 풀이법을 정리하여 제시하였다. 설계단계에서 결정되는 결정변수로는 노선(망)의 구조, 노선간격 및 위치, 정류장 간격, 배차간격, 및 소요차량수 등이 있다. 노선설계에 관한 해석적 연구에서는 시스템의 총 비용이 목적함수로 많이 사용되고 이는 이용자의 접근비용, 대기비용, 그리고 통행비용으로 구성되는 이용자비용과 운영자의 운영비용으로 구성된다. 목적함수로 사용되는 대중교통 시스템의 총 비용은 노선간격, 배차간격 등의 결정변수들에 대해 미분가능하고 미분값을 0으로 만드는 값이 존재하며 2계 미분값이 양수이기 때문에 전역 최적해가 존재한다. 따라서 목적함수의 미분값을 0으로 만드는 결정변수가 목적함수를 최소로 만드는 최적치가 되며 이 최적치에서 각 부분 함수값들은 모두 동일해지게 된다. 본 연구는 대중교통 운행계획 중 설계단계의 해석적 연구에 대한 체계적인 이해를 도모할 것이며, 관련 연구를 활성화시키는데 큰 도움이 될 것으로 기대된다.

• Journal of Nutrition and Health
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• 제30권10호
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• pp.1229-1243
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• 1997

The purpose of this study were to :(a) investigate meal costs, plate waste costs, and advantages/disadvantages of conventional /commissary foodservices and (b) compare the effectiveness of commissary foodservice systems with that of conventional systems. Questionnaires were developed and mailed to 136 schools in Kyonggi-do. A total of 106 questionnaires were usable, resulting in a 77.9% response rate. Teacher's teaching of good food habits and students satisfaction with school foodservices were surveyed in three schools from each system. Moreover, plate waste was measured to express cost and benefit in currency. Data were analyzed using the SAS package for description analysis, t-test, $\chi$$^2$ test, ANOVA, and the Vilcoxon rank sum test. Approximately seventy percent of 294schools in Kyonggi-do were operating commissary systems and most of them were of the rural (reduced paid) type. The number of meals served varied significantly between types of foodservice. The results of this study indicated that average food , labor utility , and supply costs were saved in the commissary system and that the total meal cost/person for a day was 1218.7 won compared to 1452.4 won in the conventional system. Though total meal costs were saved in the commissary system, dietitians had difficulties cooperating with school foodservice committees and supporters associations, especially in satellites of the commissary system. In addition, dietitians and teachers in the commissary system did not carry out teaching activities on good food habits to students as often as in the conventional system. Other problems that dietitians recognized in the commissary system were difficulties in training employees and parents for portion control and serving relatively simple menus. Students, as customers of school foodservices, are very important for system evaluation . Students in the commissary system scored of food itself , cleanliness of tableware, waiting time, quantity of meal and food temperature significantly lower than students in the conventional system. Moreover , the rate of plate waste was 20.5% in the commissary system as compared to 3.3% in the conventional system. Cost-effectiveness (saving 233.7won/person/day) is the main benefit of the commissary system. However , because of lower satisfaction scores and a highest plate waste rate, 201.9won/ person were wasted in the commissary system. The results of this study suggest that increasing the number of meals served within a commissary system might maximize the efficiency of the system, but increasing the number of satellites is not recommended because it might be out of dietitians control in many aspects.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 추계학술대회
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• pp.127-132
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• 2004

최근 초대형 선박이 운항을 개시하면서 6,000TEU급을 최대 수용선박으로 하여 건설된 기존 항만의 인프라 및 하역시스템 전반에 큰 변화가 올 수 밖에 없다. 그러나, 대부분 국내 컨테이너 터미널은 컨테이너 처리량에 비해 장치장 규모가 협소한 편이다. 이에 안벽장비를 추가 투입함으로써 안벽의 생산성 및 선석점유율, 선박의 대기율을 크게 향상 시킬 수 있고, 동시에 장치장 규모를 늘림으로써 비용을 낮출 수 있다. 본 연구에서는 장비를 추가 투입함으로써 향상되는 하역능력과 터미널 규모의 변화에 대해 장비비, 인건비, 건설비, 운영비 측면에서의 경제성을 기존 건설 방식과 비교${\cdot}$분석을 통해 보다 합리적인 터미널 건설 방향을 제시한다.

• 대한치과교정학회지
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• 제29권6호
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• pp.699-706
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• 1999

고정원의 조절은 교정치료에 있어서 매우 중요한 요소로 이를 보강하기 위한 많은 노력이 있어왔다. 골융합성 임프란트의 경우 확실한 고정원으로서 가능성이 인정되고 있고, 또 임상에서 많이 시도되고 있다. 그러나 임프란트를 매식하기 위해서는 무치악이 존재해야 하거나 하악구치 후방부위에 식립해야 하는 등 장소의 제약이 있고, 값이 비싸며, 골융합을 위하여 기다리는 시간이 필요하다는 등의 단점으로 인하여 보편화되고 있지는 않다. 최근 몇몇 임상가에 의하여 수술용 titanium microscrew 나 miniscrew를 교정치료시의 고정원으로 사용하려는 시도가 있었는데, 이것은 골융합성 임프란트보다 수술이 간단하며, 가격이 저렴하고, 치조골 어느 부위이든지 식립할 수 있다는 장점이 있다. 저자는 titanium microscrew implant를 사용한 skeletal cortical anchorage를 이용하여 통상적인 교정치료 동안 협조도가 고갈된 환자를 치료하였다. 6개월간의 titanium microscrew로 부터 가해진 교정력에 의하여 상악 전치부는 4 mm후방 치체이동과 압하이동을 얻었다. 통상의 교정치료에서 고정원역할을 하는 상악 구치부도 1.5 mm후방이동 되었다. titanium microscrew는 치료기간 동안 움직임없이 잘 유지되었다. 비록 과학적으로 밝혀져야할 임상적인 문제가 있기는 하나, skeletal cortical anchorage는 확실한 고정원으로서의 역할을 할 수 있을 것으로 생각된다.

• 한국항해항만학회지
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• 제30권3호
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• pp.211-217
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• 2006

최근 세계의 항만은 중국 효과 및 세계 물동량의 지속적인 증가에 따라 항만 체증은 갈수록 심화되고 있다. 선사는 선박의 대형화를 통한 물류비 절감을 위하여 기항지 항만의 축소에 따라 지역 내 항만간의 경쟁은 치열해지고 있다. 항만 체증에 따라 선사는 선박대기시간비율과 재항시간 등의 항만 서비스품질 (QoS : Quality of Service)을 기항지로 선택하는 평가기준으로 활용한다. 본 논문에서는 최근 신성장 산업의 기반 기술로 급부상하고 있는 RFID (Radio Frequence IDentification) 기술을 항만 운영시스템에 활용함으로써 트윈리프트 갠트리크레인 (Twin-lift Gantry Crane)의 하역 생산성의 개선 방안을 제안한다. 본 논문의 목적은 RFID기반의 RTLS(Real Time Location System)을 활용하여 항만 QoS가 보장되는 유비쿼터스 항만(U-Port)의 새로운 비즈니스 모델을 제안하는데 있다.

• 산업경영시스템학회지
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• 제39권1호
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• pp.81-90
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• 2016

Different from general operating policies to be applied for controllable queueing models, two of three well-known simple N, T and D operating policies are applied alternatingly to the single server controllable queueing models, so called alternating (NT), (ND) and (TD) policies. For example, the alternating (ND) operating policy is defined as the busy period is initiated by the simple N operating policy first, then the next busy period is initiated by the simple D operating policy and repeats the same sequence after that continuously. Because of newly designed operating policies, important system characteristic such as the expected busy and idle periods, the expected busy cycle, the expected number of customers in the system and so on should be redefined. That is, the expected busy and idle periods are redefined as the sum of the corresponding expected busy periods and idle periods initiated by both one of the two simple operating policies and the remaining simple operating policy, respectively. The expected number of customers in the system is represented by the weighted or pooled average of both expected number of customers in the system when the predetermined two simple operating policies are applied in sequence repeatedly. In particular, the expected number of customers in the system could be used to derive the expected waiting time in the queue or system by applying the famous Little's formulas. Most of such system characteristics derived would play important roles to construct the total cost functions per unit time for determination of the optimal operating policies by defining appropriate cost elements to operate the desired queueing systems.

• 대한안전경영과학회지
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• 제19권3호
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• pp.129-135
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• 2017

The respective delivering vehicle loaded with the own cargo moves into the respective delivery area. At the base, the delivery points D1 and D2, for example, have the same starting point but the destination is different. The average delivering time of the delivery vehicle is mostly more than 8 hours a day. Therefore, the efficiency of delivery is generally low. In this study, the deliveries will be forwarded from a base station to a delivery point where cross docking will be applied to a single vehicle, and will be distributed from the cross docking point through cross docking. If the distribution is implemented, one vehicle will not have to be operated from the base to the cross docking point. In that case, logistics cost will be reasonably saved by the reduction of transportation cost and labor time. If one vehicle only runs from the base to the cross docking point, each vehicle will be operated in two shifts, and the vehicle operation can be efficiently implemented. This research model is based on the assumption that the 3 types of ratios between the traffic volume of the vehicles starting at the base and the vehicles waiting at the cross docking point are set to the first ratio of 30% to 70%, the second ratio of 50% to 50% and the final ratio of 70% to 30%. As a result of the study, The delivery time in the cross docking point is much higher than that in present on the condition that the cargo volume in the D2 area is more than 50%. Likewise, the delivery time is slightly higher on the condition that the cargo volume is less than 50%. Time is reduced in terms of 50% model like AS-IS model.

• 한국기후변화학회지
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• 제8권3호
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• pp.265-273
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• 2017

Recently the Paris Climate Change Accord has been officially put into effect, making global efforts to implement Greenhouse Gas (GHG) reductions, and also International environmental regulations in the automotive sector will be further strengthened. The electric vehicle, which minimizes the particulate matter generated by existing internal combustion engine automobiles, is evaluated as a representative eco-friendly automobile. However, charging the battery of an electric vehicle is not fully environment-friendly if it is fueled by electricity that is being generated by fossil fuels as an energy source. The energy generated by the photovoltaic power generation system, which is an infinite clean energy, can be used to charge an electric vehicle's battery. Currently, shortage of charging facilities, time of charging, and high battery prices are the problem of activating the supply of electric vehicles. This study is to build a conjunction between the EVBSS (Electric Vehicle Battery Supply System) and ESS (Energy Storage System), which can quickly supply the photovoltaic charged battery to the required demand. If the charged battery in the Battery Swapping Station (BSS) is swapped swiftly, it will dramatically shorten the waiting time for charging the battery. As a result, if the battery is rented when it is needed, electric vehicles can be sold without the cost of a battery, which accounts for a large portion of the total cost, then the supply of electric vehicles are expected to expand. Furthermore, it will be an important alternative to maneuver climate change by minimizing GHG emissions from internal combustion engine vehicles.

• 한국항해학회지
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• 제13권3호
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• pp.37-44
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• 1989

Recently recognize the labor productivity of port physical distribution system in the port and shipping areas, Much Efforts for evaluating this productivity has been made continuously. BUt still there is little study, so far, on a systematic research for the management of port labor gangs, and even those were mainly depended on a rule of thumb. Especially the object of this study is to introduce the method of optimal allocation and assignment for the labor gangs per pier unit in the multiple ships berthed at an arbitary pier or port. In case the multiple ships have a homogeneous cargoes or do not have sufficient labor gangs to be assigned. The problem of optimal allocation and assignment of the labor gangs to be i) formalized with multi-state decision process in form of difference equation as the pattern which converted the independent multiple ships into a single ship with the intra-multiple ships, and ii) the optimal size of labor gangs could be obtained through the simple mathematical method instead of complicated dynamic programming, and iii) In case of shortage of labor gangs available the evaluation function considering the labor gangs available and total shift times was introduced, and iv) the optimal allocation and assignment of labor gangs was dealt at the point of minimizing the summation of the total shift times and at the point of minimizing the total cost charged for the extra waiting time except PHI time during port times for the multiple ships combinations.

• 한국정보처리학회논문지
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• 제5권11호
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• pp.2908-2914
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• 1998

본 논문은 교통량이 변하는 복수 교차로망의 신호등 제어에 적합한 지능형 신호 제어기를 제안한다. 교차로망이란 하나의 교차로가 사방으로 연결된 교차로이다. 기존의 교차로 제어방법들은 주로 단일 교차로를 대상으로 연구가 수행되었다. 하지만 단일 교차로 제어는 현실의 교통 상황과는 차이가 있다. 본 논문에서는 교통량과, 녹색 신호시 교차로로 진입하는 차량수와 적색 신호동안 대기하는 차량수를 퍼지 제어의 입력변수로 사용하여, 현재 녹색 현시의 확장시간을 조정하는 퍼지 교통망 제어기를 개발한다. 제안된 방법은 기존의 교차로 신호 주기 제어 방법들과 시뮬레이션을 수행하여 비교하였다. 실험결과는 제안된 퍼지 논리 제어기가 기존의 방법들에 비하여 차량당 지체시간과 논문에서 제안된 비용함수 면에서 우수함을 보여준다.