• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.100-100
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• 2016

Among various two-dimensional (2D) materials, 2D semiconductors and insulators have attracted a great deal of interest from nanoscience community beyond graphene, due to their attractive and unique properties. Such excellent characteristics have triggered highly active researches on 2D materials, such as hexagonal boron nitride (hBN), molybdenum disulfide (MoS2), and tungsten diselenide (WSe2). New physics observed in 2D semiconductors allow for development of new-concept devices. Especially, these emerging 2D materials are promising candidates for flexible and transparent electronics. Recently, van der Waals heterostructures (vdWH) have been achieved by putting these 2D materials onto another, in the similar way to build Lego blocks. This enables us to investigate intrinsic physical properties of atomically-sharp heterostructure interfaces and fabricate high performance optoelectronic devices for advanced applications. In this talk, fundamental properties of various 2D materials will be introduced, including growth technique and influence of defects on properties of 2D materials. We also fabricate high performance electronic/optoelectronic devices of vdWH, such as transistors, memories, and solar cells. The device platform based on van der Waals heterostructures show huge improvement of devices performance, high stability and transparency/flexibility due to unique properties of 2D materials and ultra-sharp heterointerfaces. Our work paves a new way toward future advanced electronics based on 2D materials.

• The Journal of Fisheries Business Administration
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• v.51 no.3
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• pp.49-71
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• 2020

A fisher means any person employed to provide his/her labor in a fishing vessel in exchange for a wage. There is no concept of a fisher in Seafarers Act. This act shall not apply to seafarers who are in service on board a fishing vessel the gross tonnage of which is less than 20 tons. However, of the total 63,112 fishing vessels, only 2,829 fishing vessels have a total tonnage of more than 20 tons. Fishermen engaged in fishing vessels with a gross tonnage of which is less than 20 tons are not guaranteed to be paid arrears through the Wage Claim Guarantee Fund for Seafarer (Article 56). In addition, fishermen working on a fishing vessel are excluded from the Wage claim Guarantee Act. The Labor Standards Act shall apply to fishermen engaged in fishing vessels with a gross tonnage of which is less than 20 tons. Fishermen and seafarers are at a higher risk of living security than regular workers. Guaranteeing the payment of wages is essential for fishermen to improve the life and employment stability. In order to guarantee fisher wage claims, the concept of a fisher in the Seafarers Act must be realized by sources such as the Wage Claim Guarantee Fund of Ministry of Oceans and Fisheries, step by step expansion of members in the wage claim guarantee fund for seafarers and interest for delayed payment of wages, etc.

• KSBB Journal
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• v.26 no.3
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• pp.189-192
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• 2011

Much interest has been recently focused on the production of large quantities of hydrogen, due to its potential importance in our economy and needs in the petroleum and chemical industries. Formate dehydrogenase H (FDH-H) from Escherichia coli containing selenocysteine that oxidizes formate to carbon dioxide with the release of hydrogen is a component of the anaerobic formate hydrogen-lyase complex of E. coli. To make full use of FDH-H, we need effective expression condition. In this approach, we investigated the effect of pH on FDH-H stability and observed the effect of selenite and formate concentration on the activity of FDH-H. Additionally, coexpression of selenocysteine insertion genes were tried to improve the expression of FDH-H. The highest level of FDH-H expression was achieved by coexpression of selenocysteine insertion genes (pSUABC) as well as by the addition of $10\;{\mu}M$ selenite and 10 mM formate. At this optimized condition, a 2.6 fold elevation of expression of FDH-H was achieved.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.1
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• pp.144-149
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• 2017

There have been lots of interest on service and entertainment robots. To ensure that robots work in harmony with humans, their stability and compactness are some of the key issues. Obviously, robots with fewer wheels occupy a smaller floor area compared to those with more wheels. In addition, robots with fewer wheels, whose posture stabilities are maintained by feedback control, are stable even under larger accelerations and/or higher locations of the center of mass. To facilitate controller design, it is assumed that both pitch and roll dynamics are decoupled. The dynamic equations of motion for the proposed robot are derived from the Euler-Lagrange equation. To obtain the optimal balancing control law, linear quadratic regulator control methods are applied to the linearized dynamic equations. Simulation and experimental results verify the effectiveness and performance of the proposed balancing control algorithm for a single-wheeled mobile robot.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1095-1098
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• 2005

Most electronic chassis control systems until today have been designed with optimization on its own performance. However, According to the increase of the interest regarding a vehicle safety and development of information technique, the integration technique of current chassis systems is being emphasized. Each enterprise proposed it with name of GCC(Global Chassis Control) or UCC(Unified Chassis Control). This study realizes control algorithm of suspension and brake by using the vehicle model of low degree of freedom as the primary stage of realization of integrated chassis control system. The proposed algorithm build the simulation environment connected to the CarSim having full vehicle model of 27 degree of freedom for raising the thrust of results

• Journal of Microbiology
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• v.40 no.4
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• pp.319-326
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• 2002

Cellular DNA in prokaryotes is organized in nucleic acid-protein self-assemblies referred to as the nucleoid. The physical forces responsible for its stability inside the poor solvent properties of the cytoplasm and their functional implications are not understood. Studies on the organisation and functioning of the cytosol of cells largely rely on experimental protocols performed in highly dilute solutions using biochemically purified molecules, which is not a reliable substitute for the situation existing in vivo. Our current research interest is focused on the characterization of biological and physical forces determining the compaction and phase separation of DNA in Escherichia coli cytoplasm. We have emphasized the effect of excluded volume in solutions with high macromolecular concentrations (macromolecular crowding) upon self-association patterns of reactions. The prokaryotic cytosol was simulated by addition of inert polymer polyethylene glycol (PEG) (average molecular weight 20000), as an agent which afterwards facilitates the self-association of macromolecules. Fluorescence microscopy was used for direct visualization of nucleoids in intact cells, after staining with DAPI (4',6-diamidino-2-phenylindole dihydrochloride). Addition of the crowding agent PEG 20,000, in increasing concentrations generated progressively enhanced nucleoid compaction, the effect being stronger in the presence of 0.2 M NaCl and 5 mM MgCl$\_$2/. Under these conditions, the nucleoids were compacted to volumes of around 2 ㎛$\^$3/ or comparable sizes with that of living cells.

• Journal of Electrical Engineering and Technology
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• v.6 no.1
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• pp.67-75
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• 2011

The development of electric vehicle power electronics system control, composed of DC-AC inverters and DC-DC converters, attract much research interest in the modern industry. A DC-AC inverter supplies the high-power motor torques of the propulsion system and utility loads of electric vehicles, whereas a DC-DC converter supplies the conventional low-power and low-voltage loads. However, the need for high-power bidirectional DC-DC converters in future electric vehicles has led to the development of many new topologies of DC-DC converters. The nonlinear control of power converters is an active research area in the field of power electronics. This paper focuses on the use of the fuzzy sliding mode strategy as a control strategy for buck-boost DC-DC converter power supplies in electric vehicles. The proposed fuzzy controller specifies changes in control signals based on the surface and knowledge on surface changes to satisfy the sliding mode stability and attraction conditions. The performance of the proposed fuzzy sliding controller is compared to that of the classical sliding mode controller. The satisfactory simulation results show the efficiency of the proposed control law, which reduces the chattering phenomenon. Moreover, the obtained results prove the robustness of the proposed control law against variations in load resistance and input voltage in the studied converter.

• Journal of Chest Surgery
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• v.18 no.1
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• pp.69-74
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• 1985

Most clinicians have taken a lot of interest in tumors arising from the bony thorax because not only of their rarity and predictable diagnosis which could be reflected as a unique radiologic shadow but also variable surgical modes for maintenance of chest wall stability encountered after en-bloc resection. By the retrospective review, we have analyzed 24 cases of primary bony thorax tumors which were experienced and surgically treated at the St. Mary`s hospital of Catholic Medical College from Jan. 1969 to Sept. 1984. The results are as follows: 1. Age incidence was evenly distributed through all decades and the male-female ratio is 15:9. 2. 16 cases out of 24 were benign tumors and the commonest one of which was fibrous dysplasia. 3. Remaining 8 cases were malignant tumors and among which osteogenic sarcoma was the commonest one. 4. The majority of tumors [22/24] were developed from the rib and the remains were from the sternum. 5. Common manifestation were palpable mass or swelling and localized tenderness. 6. Various kinds of operative procedure were underwent: single resection of rib including tumor,14 cases; multiple resection of ribs with chemotherapy or myoplasty, 2 cases; en-bloc resection of the chest wall and reconstructive procedure, 5 cases; partial resection of sternum, 1 case; bone biopsy and chemotherapy, 2 cases.

• Korean Institute of Interior Design Journal
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• no.11
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• pp.31-37
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• 1997

This study intens to provide available guideline of useful plants in interior and be used by designer. It focuses on evaluating the character of plants, the method of installation and the form of composition for suitable design of using plants. The study finds out that using plants in interior are necessary positively by 94% respondents. And results of factor analysis are that plants are needed for emothional stability(factor 1), visual charming(factor 2), and educational effection(factor 3). According to job, the group of students is visual charming (P=0.0037), the public servants and housewives is educational effection(p=0.0029). The most available space of plants as follows : Department(30.5%), Hotell(26.3%), House and Restuarant(12.7%). It has been identified that the public institution and commercial space are much indused plants. The most indused plants in house is ordered that the veranda, the living room, the entrance. This result is concerned about relation of natural light plants. The repondants reply that the favorite arrangement style is the corner form(63%), the center garden form(52.1%), the large planter(19.7%), the planter box(11.3%). They respond that they are more favorite light green color than dark, and mono color than mixture color. Finally, interior Designers should be understood the functional and aesthetic elements and the special interest about plants for developing desigv.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.3
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• pp.231-237
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• 2016

Recently, the interest in DC systems to achieve more efficient connection with renewable energy sources, energy storage systems, and DC loads has been growing extensively. DC systems are more advantageous than AC systems because of their low conversion losses. However, the DC-link voltage is variable during operation because of different random effects. This study focuses on DC voltage stabilization applied in stand-alone DC microgrids by means of voltage ranges, power management, and coordination scheme. The quality and stability of the entire system are improved by keeping the voltage within acceptable limits. In terms of optimized control, the maximum power should be tracked from renewable resources during different operating modes of the system. The ESS and VSDG cover the power shortage after all available renewable energy is consumed. Keeping the state of charge of the ESS within the allowed bands is the key role of the control system. Load shedding or power generation curtailment should automatically occur if the maximum tolerable voltage variation is exceeded. PSIM-based simulation results are presented to evaluate the performance of the proposed control measures.