• Architectural research
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• 제7권2호
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• pp.69-79
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• 2005

There are no formal decision tools or guidelines to assist owners and contractors in choosing delivery systems and project strategies that would allow for a radical reduction in project cycle time - from the preplanning phase through project start up. Therefore, it is important to identify the state-of-practice and the state-of-art on methods of achieving radical reduction defined as a reduction of 25% or more in overall project cycle time. A comprehensive literature review, three questionnaire surveys, and the seven case studies were conducted and the data obtained from them were analyzed to establish the state-of-practice and state-of-art for project cycle time reduction techniques.

• Architectural research
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• 제8권1호
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• pp.57-68
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• 2006

Global competition and reduced project life cycle ultimately puts greater performance requirements on the capital project delivery systems used to maintain competitiveness. Despite continuing improvements in delivery cycle time, business owners of facilities continue to demand greater improvements in project delivery cycle time. Therefore, it is very important to investigate the various techniques and methods leading to reduction in project cycle time and also identify the applicability of identified techniques and methods. This paper introduces reduction techniques identified through literature review (i.e, Schedule Reduction Techniques (SRTs), Management Techniques (MTs), and Construction Institute Industry (CII) Best Practices (BPs). In order to collect applicability of these techniques under different project phases (Pre-project planning (PPP), Design (D), Material Management (MM), Construction (C), and Start-up (SU)), the Essence Applicability Matrices (EAM) is used.

• 설비공학논문집
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• 제21권12호
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• pp.695-702
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• 2009

Dynamic behavior of Libr-water absorption system using low-temperature hot water was investigated numerically. Thermal-hydraulic model of single-effect/double-lift 100 RT chiller was developed by applying transient conservation equations of total mass, Libr mass, energy and momentum to each component. Transient variations of system properties and transport variables were analysed during start-up operation. Numerical analysis were performed to quantify the effects of bulk concentration and part-load operation on the system performance in terms of cooling capacity, coefficient of performance, and time constant of system. For an absorption chiller considered in the present study, optimum bulk concentration was found to exist, which resulted in the minimum time constant with stable cooling capacity. COP and time constant increased as the load decreased down to 40%, below which the time constant increased abruptly and COP decreased as the load decreased further.

• 산업경영시스템학회지
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• 제46권4호
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• pp.294-303
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• 2023

During wartime, the operation of engineering equipment plays a pivotal role in bolstering the combat prowess of military units. To fully harness this combat potential, it is imperative to provide efficient support precisely when and where it is needed most. While previous research has predominantly focused on optimizing equipment combinations to expedite individual mission performance, our model considers routing challenges encompassing multiple missions and temporal constraints. We implement a comprehensive analysis of potential wartime missions and developed a routing model for the operation of engineering equipment that takes into account multiple missions and their respective time windows of required start and completion time. Our approach focused on two primary objectives: maximizing overall capability and minimizing mission duration, all while adhering to a diverse set of constraints, including mission requirements, equipment availability, geographical locations, and time constraints.

• 디지털융복합연구
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• 제10권9호
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• pp.195-212
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• 2012

대부분의 직장인들이 미래에 대하여 불안해하면서 다양한 미래 계획들을 준비한다. 급속한 산업패턴의 변화로 직장인들의 근무기간은 점차 줄어드는 반면에 은퇴이후의 생존기간은 꾸준히 늘어나고 있는 추세에 있기 때문에 직장인들이 은퇴 이후의 대안의 하나로 창업 등에 대한 관심이 점차 높아지고 있다. 본 논문에서는 직장인들의 창업의도에 미치는 요인을 개인적요인, 심리적요인, 환경적 요인으로 구분하였다. 개인적 요인에는 경제적 노후 준비와 퇴직후 생활 전망 등과 같은 설문들로 구성되어 있다. 심리적 요인에는 위험감수 성향, 자기 효능감, 직업가치를 설명하는 창업가특성 등으로 구성되어 있다. 환경적 특성에는 사회경제적 위기 인식, 창업에 대한 인식, 고용의 불안정성 등의 설문 문항들로 구성되어 있다. 본 연구에서 설문지는 340부를 회수하여 결측값이 있는 26부를 제외하고 314부를 사용하여 SPSS Win 18.0 버전을 이용하여 분석하였다. 연구결과 개인적 요인으로 퇴직후 생활전망은 유의한 영향을 미쳤다. 심리적 요인인 위험감수성향은 창업의도에 정의 영향을 미치는 것으로 나타났다. 환경적 요인에서는 창업에 대한 부정적인 인식에 창업의도에 부정적인 영향을 미치는 것으로 나타났다. 따라서 창업에 대한 사회적 인식을 개선 등과 같은 창업 환경 개선에 대한 정책적 배려의 필요하다는 시사점을 얻을 수 있었다.

• 한국운동역학회지
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• 제17권3호
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• pp.31-39
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• 2007

The purpose of this study was to observe the kinematic pattern of elite women 100m hurdler race from start to finish and analyze how the change of horizontal velocity makes an influence on the athletes' performance. The analysis was based on the performance of Korean elite 100m hurdler A and international elite hurdlers B and C. Following results were drawn from the analyzation of elite 100m hurdlers' technical characteristics; During the race, hurdler A made more than 8 m/s of horizontal velocity at the 3rd, 4th, 6th, and the 7th hurdle. The horizontal velocity peaked at the 4th hurdle with 8.23 m/s. On the other hand, hurdler B and hurdler C maintained more than 8 m/s of horizontal velocity from the 2nd hurdle through the 10th hurdle. Hurdler B's fastest horizontal velocity was 8.67 m/s from the 6th to the 7th hurdle and hurdler C's fastest horizontal velocity was 8.85 m/s from the 5th to the 8th hurdle. From the start line to the 3rd hurdle, the times achieved by hurdlers A, B, and C were 4.90 sec, 4.65 sec, and 4.52 sec. In the middle of the race, which is from the 4th hurdle to the 7th hurdle, hurdlers A, B, and C ran in 9.10 sec, 8.60 sec, and 8.38 sec. And the latter part of the race to the 10th hurdle, the times hurdlers A, B, and C hit were 12.32 sec, 11.66 sec, and 11.32 sec. To the finish line, it took 1.15 sec for hurdler A, 1.1 sec for B, and 1.06 sec for C. Hence, to set the record of sub-13 sec, hurdler A should improve her acceleration from the start line to the 1st hurdle with the speed more than 5.4 m/s and should maintain more than 8 m/s of horizontal velocity from the 2nd hurdle through the 10th hurdle. In addition, hurdler A should improve her speed endurance to minimize the deceleration of horizontal velocity from the 4th hurdle to the final hurdle. If hurdler A could shorten 0.05 sec of time in each hurdle section, she would be able to set the record under 13 seconds.

• 벤처창업연구
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• 제16권2호
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• pp.1-17
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• 2021

벤처캐피탈과 신생 기업의 투자 관계를 다룬 기존 연구는 주로 투자자인 벤처캐피탈의 입장에서 스타트업을 선택하는데 초점을 맞추었다. 하지만 최근 벤처캐피탈 사이의 경쟁이 높아짐에 따라 기술력이 검증된 우수한 스타트업의 경우 역으로 벤처캐피탈을 선택하는 현상이 나타나고 있다. 본 연구는 스타트업이 벤처캐피탈을 선택할 경우, 벤처캐피탈과 관련된 어떤 요소가 선택에 영향을 미쳤는지 살펴보았다. 이를 위해 복수의 벤처캐피탈로부터 동시에 투자제의를 받은 경험이 있는 국내 스타트업을 대상으로 어떤 벤처캐피탈 회사를 최종 투자자로 택했는지 살펴보았다. 창업 초기단계(Pre-series A/Series A) 창업가 6명, 중기단계(Series B/C) 창업가 5명을 인터뷰하여 벤처캐피탈의 세 가지 요소: 1) 벤처캐피탈 명성(reputation), 2) 창업자와 투자자와의 관계(Relationship), 3) 벤처캐피탈이 제공하는 가치 증대 활동(Value adding service)이 선택에 미치는 영향력을 중심으로 연구하였다. 연구결과, 벤처캐피탈의 명성 중 투자포트폴리오는 매우 중요한 벤처캐피탈의 선정 기준이 되였다. 하지만, 벤처캐피탈의 운용기간과 펀드 운용액은 중요하지 않은 것으로 나타났다. 관계는 매우 중요한 요소로 나타났다. 마지막으로 벤처캐피탈의 가치 증대 활동에 대해서는 본 연구의 스타트업 창업자들은 중요하게 생각하지 않았다. 특히, 벤처캐피탈의 컨설팅과 모니터링은 오히려 스타트업에게 부담을 주는 요소로 작용했다. 본 연구는 투자 경쟁이 치열한 투자시장에서 벤처캐피탈의 투자 성공 확률을 높여주고, 벤처캐피탈과 스타트업 간의 상호 이해를 증진시켜 줄 수 있는 시사점을 제시한다.

• 대한교통학회지
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• 제12권1호
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• pp.55-73
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• 1994

The objective of this research is to evaluate the pedestrian signal time involving green and flashing green times. The minimum pedestrian green indication should give time for pedestrian to start crossing safely, and the flashing green indication should give time to complete the crossing. An average pedestrian crossing speed of 1.1(m/s) was estimated by analyzing the field data which was slower than the 1.2(m/s) currently used. Furthermore, the study proposed that design speed for the flashing green time should be slow speed for considerations pedestrian safety, not the average speed. The 0.78-1.01(m/s) of pedestrian speed was estimated at the elementary school areas that indicated 0.2(m/s) slower than the other areas. The pedestrian starting time (perception/reaction time) and time headway from front to back of herd was estimated to determine minimum pedestrian green time. the pedestrian starting time was estimated to determine minimum pedestrian green time. The pedestrian starting time was ranged 2.52-4.29 seconds. The time interval between the pedestrian rows was found to be 1.25-1.86 seconds, which declines as the pedestrian rows increases, The equation to calculate the pedestrian signal, which declines as the pedestrian rows increases. The equation to calculate the pedestrian signal time is proposed using the pedestrian starting time, the time interval between the pedestrian rows, and pedestrian crossing speed given area types (commercial, business, mixed, and elementary school areas), number of both-directional pedestrians for a cycle, crosswalk length and width.

• Journal of Mechanical Science and Technology
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• 제20권4호
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• pp.455-466
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• 2006

This study was an attempt to control and monitor Computerized Numerical Controller (CNC) machines anywhere and anytime for the development of a ubiquitous machine (u-machine). With a Personal Digital Assistant (PDA) phone, the machine status and machining data of CNC machines can be monitored in wired and wireless environments, including the environments of IMT2000 and Wireless LAN. Moreover, CNC machines can be controlled anywhere and anytime. The concept of the anywhere-anytime controlling and monitoring of a manufacturing system was implemented in this study for the purpose of u-manufacturing and u-machines. In this concept, the communication between the CNC controller and the PDA phone was successfully performed anywhere and anytime for the real-time monitoring and control of CNC machines. In addition, the interface between the CNC controller and the developed application module was implemented by Object linking and embedding for Process Control (OPC) and shared CNC memory. For communication, the design of a server contents module within the target CNC was based on a TCP/IP. Furthermore, the client contents module within the PDA phone was designed with the aid of embedded c++ programming for mobile communication. For the interface, the monitoring data, such as the machine status, the machine running state, the name of the Numerical Control (NC) program, the alarm and the position of the stage axes, were acquired in real time from real machines with the aid of the OPC method and by sharing the CNC memory. The control data, such as the start, hold, emergency stop, reserved start and reserved stop, were also applied to the CNC domain of the real machine. CNC machines can therefore be controlled and monitored in real time, anywhere and anytime. Moreover, prompt notification from CNC machines to mobile phones, including cellular phones and PDA phones, can be automatically realized in emergencies.

• 대한지리학회지
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• 제47권5호
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• pp.641-653
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• 2012

강원 영동지역의 천진호와 쌍호에서 확보한 석호 퇴적물을 분석한 결과, 천진호는 AD 780에, 쌍호는 100 BC에 벼농경이 개시된 것으로 추정된다. 두 지점이 멀지 않은 거리 내에 있고 해안으로 연결되어 있음에도 불구하고 벼농경 시작 시점에 큰 차이가 나타나고 있다. 이는 화분자료를 활용하여 특정지역 벼농경문화의 정확한 전파 시점을 파악하는 것이 쉽지 않음을 시사한다. 강원 영동 지역의 경우, 낮은 농경 생산성으로 말미암아 벼농경 문화가 최초로 전파된 시점과 벼농경이 본격적으로 시작된 시점 간에 시간적인 차이가 있었던 것으로 사료된다. 천진호 및 쌍호 분석 자료 모두에서 벼농경이 본격적으로 시작된 지 약 250년 후부터 농경지시화분들의 중요도가 더욱 커지고 산지의 침식이 빠르게 증가하는 모습이 나타난다. 이는 벼농경의 활성화로 인구가 증가함에 따라 저지대에서 산지로 거주지역의 확대가 나타났고 이로 인해 산림이 영향을 받았음을 시사한다.