• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.1
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• pp.1-8
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• 2018

A problem exists in the conventional transportation cart applications, in which an external power supply with mechanical contact connection (bus bar connection) is required to drive the motor. Therefore, continuous effort for maintenance is required, aside from the expensive bus bar connector. To solve this problem, a self-electricity-generated transportation cart system without bus bar has recently been introduced. In this system, a battery needs to store the power of the generated wheel, and a boost converter, which converts the low battery voltage to high bus voltage to drive the motor inverter, is necessary. However, since the instantaneous large current required for starting the motor is supplied from the battery, a battery with large size and volume should be adopted to withstand this large current. In this study, a boost converter that can supply a large instantaneous current by using super Capacitor string is proposed. The proposed converter can be realized with a small size and volume compared with the conventional battery-fed boost converter. Operational principles, analysis, and design of the proposed converter are presented, and experimental results are provided to validate the proposed converter.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8A
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• pp.838-845
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• 2008

In this study, we developed a OBE(On Board Equipment) system in which moving cars communicate directly each other to exchange traffic information. this system achieved by using DSRC(Dedicated Short Range Communication). this technology can improve the fidelity of collected information by transferring current state information from a moving car to center in real time. As a consequence of it, moving cars can be offer information service of hight quality even in a shadow zone. and also, in addition to basic ETC function for toll payment, using our newly developed system, delivering traffic information and providing additive service like GPS can be achieved by car-to-car direct communication within shadow areas without additional infra-structure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.738-745
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• 2001

In this paper, when the moving object move to the three-dimentional space, the tracking system track the moving object using the fuzzy reasoning. The joint angle el of the manipulator rotate from $0^{\circ}\; to\; 360^{\circ}$ , and the joint angle $\theta_2$rotate from$0^{\circ}\; to\; 360^{\circ}$. The fuzzy singleton is used for fuzzification and the control rule is twenty five and the fuzzy inference method is simplified Mamdani's reasoning and the defuzzification is the SCOG(Simplified Center Of Gravity) of the fuzzy controller To measure of the performance of the designed system, the fuzzy controller is compared with the CTM(Computed Torque Method) controller at the same condition. when the disturbance torque is ON, the both of CTM and fuzzy controller tracked object without error, However, the disturbance torque changed 0.4N, the CTM controller is 10 times greater than fuzzy controller at the sum of absolute error difference. The designed system is showed it's robustness against with disturbance.

• Journal of Digital Convergence
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• v.19 no.8
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• pp.173-184
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• 2021

For the current organizations, retaining executive members is one of the most important functions of human resource management. Given that importance, although executives' mobility becomes prevalent, most prior studies tended to focus on involuntary turnover of executive members. To fill this gap, the current theoretical paper suggests a model of executive voluntary turnover, drawing on the lierature of employee mobility and entrepreneurship. First, running a new business as a CEO negatively affects prior-firm performance, but collaboration between two firms mitigate the negative association. Second, spin-off positively affects prior-firm performance, but this is weakened as spin-off firm performance decreases. Finally, moving to a competitor negatively, while moving to a collaborator positively affects prior-firm performance.

• Journal of KIISE
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• v.43 no.12
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• pp.1428-1436
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• 2016

A multipath routing in wireless sensor networks (WSNs) provides advantage such as reliability improvement and load balancing by transmitting data through divided paths. For these reasons, existing multipath routing protocols divide path appropriately or create independent paths efficiently. However, when the sink node moves to avoid hotspot problem or satisfy the requirement of the applications, the existing protocols have to reconstruct multipath or exploit foot-print chaining mechanism. As a result, the existing protocols will shorten the lifetime of a network due to excessive energy consumption, and lose the advantage of multipath routing due to the merging of paths. To solve this problem, we propose a multipath creation and maintenance scheme to support the mobile sink node. The proposed protocol can be used to construct local grid structure with restricted area and exploit grid structure for constructing the multipath. The grid structure can also be extended depending on the movement of the sink node. In addition, the multipath can be partially reconstructed to prevent merging paths. Simulation results show that the proposed protocol is superior to the existing protocols in terms of energy efficiency and packet delivery ratio.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.3
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• pp.17-24
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• 2021

Perovskite solar cells (PSCs) can be fabricated through solution process economically with variable bandgap that is controlled by composition of precursor solution. Tandem cells in which PSCs combined with silicon solar cells have potential to reach high power conversion efficiency over 30%, however, lack of long-term stability of PSCs is an obstacle to commercialization. Degradation of PSCs is mainly attributed to the mass transport of halide and metal electrode materials. In order to ensure the long-term stability, the mass transport should be inhibited. In this study, we confirmed degradation behaviors due to the mass transport in PSCs and designed buffer layers with LiF and/or SnO₂ to improve the long-term stability by suppressing the mass transport. Under high-temperature storage test at 85℃, PSCs without the buffer layers were degraded by forming PbI₂, AgI, and the delta phase of the perovskite material, while PSCs with the buffer layers showed improved stability with keeping the original phase of the perovskite. When the LiF buffer and encapsulation were applied to PSCs, superior long-term stability on 85℃-85% RH dump heat test was achieved; efficiency drop was not observed after 200 h. It was also confirmed that 90.6% of the initial efficiency was maintained after 200 hours of maximum power tracking test under AM 1.5G-1SUN illumination. Here, we have demonstrated that the buffer layer is essential to achieve long-term stability of PSCs.

• Korean Journal of Ichthyology
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• v.11 no.2
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• pp.143-148
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• 1999

Two sibling species of the genus Platycephalus collected from the South and West Sea of Korea were reviewed based on the several meristic and morphological characters, electrophoresis of muscle protein, and LDH and MDH isozyme. Counts and morphometric characters of Platycephalus indicus were different from those of Platycephalus sp. by having 18~20 pectoral fin rays (16~19 in Platycephalus sp.), 70~80 scales of lateral line (83~100), 10.2~13.1% eye diameter (10.9~15.5%), 14.5~18.1% interorbital width (11.8~17.8%), dark brown of body color (light brown) and dark brown of pectoral and ventral fin outside (light brown and pale). The number of soluble protein bands in muscle separated by polyacrylamidegel electrophoresis was 16 and 18 from P. indicus and Platycephalus sp, respectively, and each bands showed their characteristics in activated degree. The number of bands separated from LDH isozyme were 2 and 1 in P. indicus and Platycephalus sp. and in the case of MDH isozyme, 5 and 4 bands, respectively. So we were thought that P. indicus and Platycephalus sp. from Korea were different species each other.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.5
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• pp.633-642
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• 1994

Distribution of ichthyoplankton in the adjacent waters to Kori were surveyed during the period from April, 1991 to January, 1992. The dominant fish eggs included the eggs of Engraulis japonica, Maurolicus muelleri, Callionymus spp. and others. The eggs of Engrualis japonica and Maurolicus muelleri were $79.52\%$ and $1.86\%$ of the total eggs abundance, respectively. A total of 15 taxa of fish larvae were found. The dominant species was Engraulis japonica accounting for $52.39\%$ of the total larvae and followed by Callionymidae fish($29.36\%$). Other major species were Stephanolepis cirrhifer($6.30\%$), Sebastes schlegeli($3.16\%$), Ammodytes personatus($1.33\%$) and Girella punctata($1.70\%$). These 6 taxa constituted $94.30\%$ of the total larvae collected. In this area, distributions of warm water had a great influence on larvae and juvenile distribution which usually is along the coast and the other places where there layer water movements since, upwelling in the open sea affects ichthyoplankton distribution.

• The Journal of Korean Philosophical History
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• no.41
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• pp.247-270
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• 2014

Multiculturalism may be deeply connected with the diversities of cultures and enlightenment discussed in the context that we live together with the specification of cultures derived from any spatial conditions overtly and covertly. People live on their own customs compatible with their space and the time, and they make their boundaries of races, nations, and national memories. In such a way each of them treats each other exclusively and is inclined not to recognize being of the others. Also people are apt to recognize the others unessentially and overlook the others's value and way of life. As a result they might destroy the foundation of symbiotic livings conditions on their own. On the other hand they pretend to search for the cultural diversities of the others and include them under their own universalities, resulting in conflicts. Hence it is required that we should make an efforts to prepare the fields for living together through getting over the problem of the recognition of matters and affairs before us. From the above-told critical mind this thesis seeks the multicultural relativities and more arrives at the relationalities discussed by East-Asiatic philosophers of Chuang Tzu and Ch'oe Han-gi. Especially by gazing at the idea of the interconnectedness which means activities, changeabilities and mobilities, appeared on the idea of Ch'oe Han-Gi's revolving transformation, it is stressed that the communications of the local with each other in the various aspects of, e.g. materials, regions and cultures should be achieved.

• Journal of the Korean Geophysical Society
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• v.2 no.2
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• pp.91-99
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• 1999

A high-resolution seismic profile acquired across the northeastern boundary of the Pungam Basin, one of the Cretaceous sedimentary basins in Korea, has been interpreted to delineate subsurface geological structures across the basin boundary. We identified boundary faults and unconformity surfaces of the basin and divided sediment body into three seismic depositional units (Units I, II, and III from youngest to oldest). Inferred from fault geometry and type, northeastern part of the Pungam Basin has been formed by a strike-slip fault whereas the normal faults near the boundary were formed by transtensional movement along a fault zone. A 350-400 m thick sediment layer is overlying the Precambrian gneiss. Bedding planes of Unit III are dipping westward and are closely related to an anticline in the acoustic basement. Unit II is also tilted westward, suggesting that the eastern part of the fault zone was uplifted after deposition of lower part of the sedimentary body. Afterward, the uplifted sediment layers were eroded and transported to the western part of the basin. Chaotic reflection pattern of sedimentary Units II and III may suggest that strike-slip movement along the fault zone deformed basin-filled sediments.