• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.359-366
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• 2013

Although many research efforts have been conducted to address the effect of crew members' work skills (e.g., technical and planning skills) on work performance (e.g., work duration and quality) in construction projects, the relationship between skill and performance has generated a great deal of controversy in the field of management (Inkpen and Crossan 1995). This controversy can lead to under- or over-estimations of the overall project schedule, and can make it difficult for project managers to implement appropriate managerial policies for enhancing project performance. To address this issue, the following aspects need to be considered: (a) work performances are determined not only by individual-level work skill but also by the group-level work skill affected by work team members, each member's role, and any working behavior pattern; (b) work planning has significant effects on to what extent work skill enhances performance; and (c) different types of activities in construction require different types of work, skill, and team composition. This research, therefore, develops a system dynamics (SD) model to analyze the effects of both individual-and group-level (i.e., multi-level) skill on performances by utilizing the advantages of SD in capturing a feedback process and state changes, especially in human factors (e.g., attitude, ability, and behavior). The model incorporates: (a) a multi-level skill evolution and relevant behavior development mechanism within a work group; (b) the interaction among work planning, a crew's skill-learning, skill manifestation, and performances; and (c) the different work characteristics of each activity. This model can be utilized to implement appropriate work planning (e.g., work scope and work schedule) and crew management policies (e.g., work team composition and decision of each worker's role) with an awareness of crew's skill and work performance. Understanding the different characteristics of each activity can also support project managers in applying strategic work planning and crew management for a corresponding activity, which may enhance each activity's performance, as well as the overall project performance.

• 한국자동차공학회논문집
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• 제16권4호
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• pp.1-7
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• 2008

Recent trends of development in small size gasoline engines are both to have higher compression ratio for the purpose of improved fuel consumption and to advance spark timing up to DBL in a low to mid engine speed region for a good acceleration performance of vehicles. However, there occurs the deviation of corrected engine torque results during engine performance test on dynamometer because test conditions influence the onset of knock. Therefore, this research shows the test deviation of corrected engine torque decreases when knock correction rate is used.

• 대한조선학회논문집
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• 제41권6호
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• pp.114-119
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• 2004

For passenger vessels, twin shaft types in propulsion system is generally adopted to provide a high-speed performance in low draught due to restricted operating condition in harbors or water channels. Struts of twin open shaft type support the shafts, bearings, and propellers. Therefore, strut design is needed to consider not only hydrodynamic performance but also structural and noise/vibration performance, In this paper, considerations in strut design at the initial design stage have been discussed based on existing references, numerical calculations, and their comparisons. Also, the strut design of a RoPax ferry has been carried out at the initial design stage, for an example.

• Journal of Positioning, Navigation, and Timing
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• 제6권2호
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• pp.43-51
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• 2017

In this study, the effect of the steering vector model mismatch due to array uncertainties on the performance of array processing was analyzed through simulation, along with the alleviation of the model mismatch effect depending on array calibration. To increase the reliability of the simulation results, the actual steering vector of the array antenna obtained by electromagnetic simulation was used along with the Jahn's channel model, which is an experimental channel model. Based on the analysis of the power spectrum for each direction, beam pattern, and the signal-to-interference-plus-noise ratio of the beamformer output, the performance deterioration of array processing due to array uncertainties was examined, and the performance improvement of array processing through array calibration was also examined.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.881-885
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• 2018

In order to develop a gas circuit breaker (GCB), the breaking performance of the short line fault (SLF) should be prioritized over that of the breaker terminal fault (BTF). In brief, it is necessary to evaluate the thermal characteristics of the insulating gas that is filled in a GCB. In the process of developing a GCB, many companies use the simplified synthetic testing facility (SSTF).In order to evaluate the SLF breaking performance of a GCB with a long minimum arcing time, a modifications to the conventional SSTF was proposed. In this study, we developed the SSTF with a modified transient recovery voltage circuit. The performance of the newly developed SSTF was verified by an $L_{90}$ breaking performance test on a rating combination of 170 kV, 50 kA, and 60 Hz.

• Computers and Concrete
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• 제5권2호
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• pp.135-154
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• 2008

This paper presents a nonlinear finite element analysis procedure for the seismic performance assessment of reinforced concrete bridge piers with unbonded reinforcing or prestressing bars. A computer program named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) is used to analyze reinforced concrete structures; this program was also used in our study. Tensile, compressive and shear models of cracked concrete and models of reinforcing and prestressing steel were used account for material nonlinearity of reinforced concrete. The smeared crack approach was incorporated. To represent the interaction between unbonded reinforcing or prestressing bar and concrete, an unbonded reinforcing or prestressing bar element based on the finite element method was developed in this study. The proposed numerical method for the seismic performance assessment of reinforced concrete bridge piers with unbonded reinforcing or prestressing bars is verified by comparison of its results with reliable experimental results.

• 한국컴퓨터정보학회논문지
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• 제21권11호
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• pp.49-57
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• 2016

In this paper, we propose the novel tracking method which uses the weighted discriminative correlation filter (DCF). We also propose the PSPR instead of conventional PSR as tracker performance evaluation method. The proposed tracking method uses multiple DCF to estimates the target position. In addition, our proposed method reflects more weights on the correlation response of the tracker which is expected to have more performance using PSPR. While existing multi-DCF-based tracker calculates the final correlation response by directly summing correlation responses from each tracker, the proposed method acquires the final correlation response by weighted combining of correlation responses from the selected trackers robust to given environment. Accordingly, the proposed method can provide high performance tracking in various and complex background compared to multi-DCF based tracker. Through a series of tracking experiments for various video data, the presented method showed better performance than a single feature-based tracker and also than a multi-DCF based tracker.

• Journal of Communications and Networks
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• 제17권2호
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• pp.118-125
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• 2015

In this paper, we propose a method to reduce mobile social network services (SNSs) traffic using a mobile integrated SNS gateway (MISG) to improve network communication performance between the mobile client and SNS servers. The gateway connects the client and SNS servers using the contents adapter and the web service adapter and helps to improve communication performance using its cache engine. An integrated SNS application, the user's client, communicates with the gateway server using integrated SNS protocol. In addition, the gateway can alert the client to new SNS contents because of the broker server implemented by the message queuing telemetry transport protocol. We design and develop the modules of the gateway server and the integrated SNS application. We then measure the performance of MISG in terms of content response time and describe the result of the experiment.

• 한국운동역학회지
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• 제27권3호
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• pp.219-227
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• 2017

Objective: The aim of this study was to analyze the effects of bobsleigh shoes on the lower extremity range of motion and start speed lap time and to develop bobsleigh shoes suitable for winter environments and Korean players based on sports science and optimized biomechanical performance. Background: The bobsleigh shoes used in the start section of the sport are one of the most important equipment for improving athletes' performances. Despite the importance of the start section, there are no shoes that are specifically designed for Korean bobsleigh athletes. Thus, Korean athletes have to wear sprint spike shoes instead of bobsleigh shoes to practice the start. Method: The subjects included four bobsleigh athletes from the Gangwon Province Bobsleigh Skeleton Federation. The study selected the bobsleigh shoe type A (company A) and type B (company B). We analyzed the lower extremity range of motion and sprint time (start line to 10 m) using a Motion Analysis System (USA). Results: In the measurement of the time required for the bobsleigh start section (10 m), the type A shoes demonstrated the fastest section record by $2.765{\pm}0.086sec$ and yielded more efficient movements, hip and knee flexion, hip extension, ankle dorsiflexion, plantar flexion, and inversion than the type B shoes. Conclusion: Type A shoes can yield a better performance via effective lower extremity movements in the bobsleigh start section. Application: In the future, functional analysis should be conducted by comparing the upper material properties, comfort, and muscle fatigue of bobsleigh shoes based on the Type A shoes to develop such shoes suitable for Koreans.

• 한국산림과학회지
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• 제94권3호통권160호
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• pp.153-160
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• 2005

본 논문은 우리나라 기능인 영림단에 대하여 1999년부터 2003년까지 5년 동안의 영림단 운영실적을 분석하였으며, 그 결과를 통하여 영림단의 운영개선 방안을 제시하고자 한다. 먼저 기능인 영림단의 연간 사업일수가 너무 적어 수입이 낮고, 영림단원의 이탈을 방지하기 위하여 일반적인 숲 가꾸기 공공근로 사업을 줄이고 통합육림 사업을 확대하여, 연중 안정적으로 작업 할 수 있도록 사업량을 확대하여 기능인 영림단의 생계유지 및 소득을 증대시켜야 할 것이다. 모든 영림단원을 임업기능인 훈련교육을 받은 자격을 갖춘 영림단으로 유도하며, 국유림 영림단원이 숲 가꾸기 공공근로 사업에 참여할 경우 일반근로자와 구별하여 별도 수당을 지급해야 한다. 또한 미래의 기계화를 위해서도 기술자를 양성해야 하며, 교육훈련을 통해 기능화하고 자격증 보유비율을 높이도록 하며, 기능인 영림단의 산림작업 능력 향상과 전문 직업의식 고취를 위하여 기계화 교육을 실시하여 기계화률 정착시키며, 교육기간에는 일정한 수당을 지급해야 하는 것으로 판단되었다.