• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.4
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• pp.21-28
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• 2006

In this paper, the proposed full-bridge high frequency isolated zoo voltage and zero current switching phase shifted pulse width modulation(ZVZCS PS-PWM)DC-DC converter among fuel cell generation system consist of 1.2[kW] fuel cell of Nexa Power Module, full-bridge DC-DC converter to boost the fuel cell low voltage($28{\sim}43[%]$) to 380[VDC] and a single phase full-bridge inverter is implemented to produce AC output(220[VAC], 60[Hz]). A tapped inductor filter with freewheeling diode is newly implemented in the output filter of the proposed full-bridge high frequency isolated ZVZCS PS-PWM DC-DC converter to suppress circulating current under the wide output voltage regulation range, thus to eliminate the switching and transformer turn-on/off over-short voltage or transient phenomena. Besides the efficiency of $93{\sim}97[%]$ is obtained over the wide output voltage regulation ranges and load variations.

• Journal of Navigation and Port Research
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• v.37 no.1
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• pp.71-77
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• 2013

Most of the maritime accidents are the crash that occurred by complex coastal terrain, increased maritime traffic and frequent weather changes. Therefore, transportation safety is exactly determined using accurate environmental informations, but if informations are inaccurate or insufficient, accident risk can be increased. Therefore, ship need the system that can accurately generate transportation safety information. This paper proposes the transportation safety system and performance evaluation in the real environment. The proposed system includes database of environment informations and navigation algorithm using PPP method to estimate the accurate ship position. Therefore, this system can accurately calculate distance or freeboard between ship with other factors. Futhermore, when weather is deteriorated, crew can sail with database based 3-D monitoring module in the transportation safety system. To verify the function and performance, data of Kyungin ARA waterway and ferry is used to evaluation.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.2
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• pp.96-105
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• 2011

Ubiquitos sensor network(USN) is a technology which is widely used in our life. This paper introduces an example of design and implementation for a system which is based on the USN technology and can provide an efficient management tool for a space that should be precisely controlled for a certain range of uniformity in temperature and humidity. This introduced system builds a wireless sensor network using a number of sensor modules that are equipped with temperature and humidity sensors, and collects temperature and humidity information in real-time while simultaneously providing a method for monitoring the status of temperature and humidity by the graphical user interface. Also, the system will give a warning signal if the monitored values are differ from the pre-specified values of temperature and humidity for each sensor module more than a certain amount of tolerance. This temperature and humidity logging and monitoring system can perform better management for the space easily and efficiently by automating the existing manual method for data collection and management. Furthermore, using the stored data, it can make possible to perform post-analysis on the problems caused by temperature and humidity and to obtain information for environmental enhancement for the space.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.3
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• pp.1-10
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• 2011

Social network service is defined as an online service or communication service based on social relations among people applied the concept of social network. Social collaborative service included in social network service is characterized by the new value of modified content or recreated content made through collaborative creation process between members of the group. It has the remarkable merits such as sharing and collaboration. But, at the same time, it has the latent problems such as content reuse or copy that is not allowed for members to use. It has been emerged that UCC which is a typical example of recreated or modified content has the copyright issues in both creation and publishing step. To resolve this matter, we don't have many appropriate methods except CCL so far. So, in this paper, we define the problem and implement the UCC metadata manager to control metadata reflecting the feature of UCC. We draw the reference metadata element to identify original content utilized re-creation process. After that we define the R.Metadata Loader module based on the use case. Finally, the proposed UCC metadata manager provides the information of referenced content and lets us to identify the relationship between reference contents. So as to implement prototype, we use Kaltura which is CMS using open source and obtain functional extensibility of metadata manager by using open API.

• Korean Journal of Construction Engineering and Management
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• v.15 no.1
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• pp.11-19
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• 2014

The Construction industry is a labor-intensive industry that its labor cost takes up about 30~40% out of the whole construction cost. However, due to a stereotype that on-site work is a 3D job there is a shortage of the labor forces. Modular construction method is to produce modular units in the plant so that workers could work stably. Also, after delivering the module from plant to the site, there will be only installment to be required that shortens construction duration. Even though the modular market is currently expanding based on military facilities in Korea, its best strengths are not demonstrated well which are shortened construction period and low cost. It also causes labor problem of production due to minimum utilization of the modular construction method. Multi-skilled labor means a technician that is able to perform more than two kinds of work with more than two techniques. Multi-skilled labor can proceed smoothly by figuring out the connectivity between the precedent and following operations. Therefore, this research is to apply the concept of Multi-skilled labors, suggest solutions and allocate manpowers efficiently. As a result, it helps to decrease idle manpowers during the operation and the total labor forces can be saved. Low cost is the original strength of the modular which can stand out so the modular market is expected to expand.

• Korean Journal of Construction Engineering and Management
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• v.21 no.6
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• pp.84-94
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• 2020

Modular architecture is very important not only in the design phase but also in the construction planning phase because it affects construction methods and module sizes depending on transport equipment. There are economic risks as well as quality, as there may be defects such as internal interiors or elimination of deadlines during transportation, and structural torsion caused by rainfall and shock. However, there is a lack of objective criteria or data to refer to in determining transport equipment that has a material effect on transport. Accordingly, there is no decision model to determine the optimum transportation equipment for each construction site. Therefore, it is necessary to develop a decision support model that can be compared to the review of transport equipment selection factors. The purpose of this study is to propose the transport equipment impact factors and decision support models for systematic review and objective decision making of each construction plan in the construction of small and medium-sized modulators. The decision model proposed in this study can be used as basic data for transport studies, ensuring objectivity and transparency in the equipment selection process.

• Journal of Distribution Science
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• v.14 no.2
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• pp.65-72
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• 2016

Purpose - Recently on-the-job training (OJT) has become the most preferred training and development method with the emergence of the concept that workplace is the best place where learning take place. But many researchers argue that OJT is not helpful for the performance of organization because OJT is not systematic and mostly depend on quality of trainer. Since Jacobs & McGriffin introduced S-OJT (structured OJT), there has been plenty of researches. But most of the researches have focused mainly on employee's attitude and organizational performance caused by S-OJT and neglected a holistic approach of S-OJT as a system. S-OJT need to be analyzed comprehensively to understand training performance because S-OJT is operated as a system consist of input, process, and organizational context. Although S-OJT may create unintended consequences, there were few researches to explore them. Thus, the purpose of this study is to identify the critical success factors for S-OJT and to find unintended consequences of it. Research design, data and methodology - We conducted a case study on M business unit of A company which developed and has been implementing S-OJT program for years. We designed and prepared the process, collected and analyzed data for the study. We set the theoretical framework to analyze the case after reviewing theories and previous studies on S-OJT. We collected and analyzed internal reports and interview results of the employees of the M business unit. We tried to collect as many information as possible to secure the validity of the research results. Results - The critical success factors identified in the study are as follow. First, it is important to select and train proper trainers for S-OJT. Second, it is needed to develop structured training module. Third, organization have to use effective communication system like on-line community. Forth, trainer should have proper skills for training such as facilitating skill, coaching skill, and delivering skill etc. Fifth, proper learning place is needed. Sixth, organizational support is important especially, immediate supervisor support and concern is critical. Eleventh, it is needed to consider situational contexts. Among them, overload to the trainer will affect the effectiveness of S-OJT. In this study, we found an additional unintended consequence. "To teach is the best way to learn." Experience as a trainer give employee an opportunity to organize one's knowledge and skill and to attain facilitation skill, coaching skill, and relation skill. Thus, organization may use S-OJT to train the potential talent. Conclusions - Many organizations introduced S-OJT to train the newcomers because S-OJT drew attention as an important tool to develop employees. Following this trend, there has been increasing number of researches to find the results of S-OJT and identify the determinants of S-OJT success. However, most of the researches concentrated on finding effects of some factors neglecting holistic approach. This study tried to identify critical success factors affecting effectiveness of S-OJT by using case study and find additional unintended consequence. The results of the study will be useful for organizations which have a plan to adopt S-OJT.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.2
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• pp.75-84
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• 2005

This research is to design a high performance NAND-type flash memory package with a smart buffer cache that enhances the exploitation of spatial and temporal locality. The proposed buffer structure in a NAND flash memory package, called as a smart buffer cache, consists of three parts, i.e., a fully-associative victim buffer with a small block size, a fully-associative spatial buffer with a large block size, and a dynamic fetching unit. This new NAND-type flash memory package can achieve dramatically high performance and low power consumption comparing with any conventional NAND-type flash memory. Our results show that the NAND flash memory package with a smart buffer cache can reduce the miss ratio by around 70% and the average memory access time by around 67%, over the conventional NAND flash memory configuration. Also, the average miss ratio and average memory access time of the package module with smart buffer for a given buffer space (e.g., 3KB) can achieve better performance than package modules with a conventional direct-mapped buffer with eight times(e.g., 32KB) as much space and a fully-associative configuration with twice as much space(e.g., 8KB)

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.10
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• pp.1061-1070
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• 2009

In this paper, we have designed TDL(True-time Delay Line) for eliminating beam-squint occurring in active phased array antenna with large electrical size operated in wide bandwidth, and have tested its electrical performance. The proposed TDL device is composed of 4-bit microstrip delay line structure and MMIC amplifier for compensation of the delay-line loss. The measured results of gain and phase versus delay state satisfy the electrical requirements, also P1dB output power and noise figure meet the requirement. To verify the performance of fabricated TDL, we have simulated the beam patterns of wide-band active phased array antenna using the measured results and have certified the beam pattern compensation performance. As a result of simulated beam pattern compensation with respect to the 675.8 mm size antenna which is operated in X-band, 800 MHz bandwidth, we have reduced the beam squint error of ${\pm}1^{\circ}$ with ${\pm}0.1^{\circ}$. So this TDL module is able to be applied to active phase array antenna system.

• Korean Journal of Construction Engineering and Management
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• v.17 no.3
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• pp.143-155
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• 2016

Recently, the interest on applying AVM(Around View Monitoring) systems in construction equipments have been increasing due to the demand for better control, work efficiency and safety. Most of the existing AVM systems have been developed focusing on the application in automobiles and only several AVM systems have been developed for construction equipments. However, the original technology of AVM remained the same as in the automobiles that failed to consider the main properties of construction equipments and suggest appropriate range of AVM display (Top-view). Therefore, the purpose of this study is to suggest a pilot type of AVM system for construction equipment. Accordingly, literature review, deduction of main consideration factors, selection of sensors, system design, algorithm development of a pilot type of AVM system for construction equipment have been conducted. A laboratory experiment has also been conducted for the deduction of further improvements. As a result, a minimum image refresh rate of 20 fps has been achieved that clearly reflects the actual situation of the equipment and also, the actual motions of Boom, Arm, Bucket have been displayed appropriately on the AVM system based on the angle data collected by sensors. However, the experiment results have also shown that the following tasks still remain for future work: 1)Improvement of AVM image interpolation, 2)Development of calibration module for variety construction equipment.