• Tribology and Lubricants
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• v.10 no.4
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• pp.33-42
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• 1994

An influence of inlet pressure on the performance of sector-shaped pad thrust bearings is investigated theoretically. The optimum conditions of film thickness or the optimum positions of pivot are found through the evaluation of load capacity for all available conditions of film thickness, under the operating conditions which the thermal and pad deformation effects can be neglected. The bearing performance including the inlet pressure effects is obtained for a wide operating ranges that inertia parameter(Re$^{*}$) is up to unity, and for the various cases of pad extent angle (number of pad) and the three cases of the angle between pads. The results show that the inlet pressure has a large influence on the performance of sector-shaped pad thrust bearings. In the design of sector-shaped pad bearings, due to the inlet pressure, the optimum number of pad is varied with the operating speed and the angle between pads, and the optimum position of pivot is located toward the leading edge along with the operating speed increases.

• Journal of Advanced Navigation Technology
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• v.24 no.4
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• pp.299-304
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• 2020

This paper proposes the design of circular sector shaped power divider-combiner with a planar structure. This structure can be constructed in series, and due to the circular sector shape, it is possible to simplify circuit configuration and improve the amplitude and phase balanced characteristics of the output. It has a simple input matching circuit and an RC parallel circuit was inserted between the output ports to improve the reflection coefficient and isolation of the output. Since the designed divider-combiner are structurally designed in a symmetrical shape of a sector, even if the output ports are composed of two or four output ports, they have excellent characteristics with an amplitude balance of ± 0.1 dB and a phase balance of ± 1o between outputs. To prove these characteristics, it was confirmed that the characteristics of the planar power divider-combiner fabricated at an operating frequency of 2 GHz are in good agreement with the simulation.

• Journal of Communications and Networks
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• v.6 no.2
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• pp.106-111
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• 2004

The uplink capacity and the interference statistics of the sectors of the cigar-shaped W-CDMA microcells are studied. A model of 9 base station, assumed to be in a long tunnel, is used for the uplink analysis. The capacity and the interference statistics of the microcells are studied for different sector ranges, different propagation exponents, different antenna sidelobe levels, and different bend losses.

• Journal of Korea Trade
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• v.25 no.7
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• pp.1-18
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• 2021

Purpose - In this study, we explore the relationship between the degree of internationalization (DOI) and firm performance (DOI-P) of small and medium-sized enterprises (SMEs) in the manufacturing sector. Specifically, we investigate whether the costs and benefits dynamics concerning the internationalization of SMEs differ between high-tech and non-high-tech industries. Design/methodology - We extend the prior literature on this relationship by employing 5-year data on 589 Korean SMEs in the manufacturing sector and examining the moderating impact of the industry characteristics. Our findings reveal a U-shaped relationship between the DOI and SME performance. High-tech SMEs demonstrate an inverted U-shaped relationship, whereas non-hightech SMEs exhibit a U-shaped relationship. Findings - Our findings illustrate the importance of the industry factor in testing the performance impact of the internationalization of Korean SMEs. By incorporating industry dynamics, our results indicate that the DOI-P relationship depends on the context of the industry in which an SME operates. High-tech SMEs also display a higher DOI but are outperformed by non-high-tech SMEs for the entire internationalization path, which implies that high-tech SMEs face more challenges than non-high-tech SMEs while seeking internationalization. Originality/value - The findings strongly validate that significant benefits exist for SMEs undertaking internationalization. We also employ the contextual framework contributing to increasing the understanding of the intrinsic value of internationalization and resolving the mixed results issue on the DOI-P relationship, by illustrating that the industry factor leads to different dynamics of costs and benefits of SME internationalization; it also determines the shape and direction of the relationship.

• Tribology and Lubricants
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• v.15 no.1
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• pp.24-28
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• 1999

This paper describes a new pivoting technique to improve bearing performance in pivoted pad thrust bearings. This new technique adjusts the pivot line in a line pivoted pad thrust bearing to be parallel to the trailing edge of a sector shaped pad. Bearing performance factors such as load carrying capacity, frictional torque and flow rate are numerically investigated for conventional point-pivoted and line-pivoted pads and for the new parallel-line pivoting technique. It is shown that the load carving capacity can be maximized with the new technique.

• Architectural research
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• v.16 no.4
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• pp.139-147
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• 2014

The purpose of this study is to explore institutional frameworks to professionalize housing management in Korea. In particular, this research reviews the evolution of professional housing management and its institutional measures in a social constructionist perspective. The main method employed in the study is content analysis in which historical pathways in institutionalization of professional housing management are examined and a wide array of indices from secondary data are drawn out in relation to various actors. The findings show that a series of institutional measures were taken from 1970s to secure the professionalization of housing management ranging from introduction of housing management bylaws, placement of licensed housing managers, legal requirements of professionally managed housing estates, compulsory operation of long-term reserve funds, formation of residents' association, mandatory establishment of long-range maintenance planning, to standardization of multifamily housing management bylaws. Since the Multifamily Housing Management Ordinance of 1979 amended in 1980s, many institutional measures have been legally enforced and shaped contemporary practices of professional housing management such as an association for housing management companies, qualification of on-site housing management agents, national licensing examination for housing managers, an organization for licensed housing mangers, mandatory registration of housing management companies, disclosure of monthly housing management fees, and formalization of public assessment of housing management. In spite of the distinctive marks in the professionalization of housing management, more proactive and competitive approaches to the international professionalization need to be considered.

• Animal Systematics, Evolution and Diversity
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• v.36 no.4
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• pp.285-295
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• 2020

Adults of Prosimulium kiotoense and Twinnia japonensis were collected and reported from Korea for the first time. Since adult black flies are notorious for morphological homogeneity particularly in female, larval and pupal characters have been mainly used to identify them. Adults of P. kiotoense can be identified by the following combination of characteristics: Adult, wing with radial sector (Rs) branched into R²⁺³ and R⁴⁺⁵; hind leg basitarsus without calcipala; first tarsomere without pedisulcus. Female, claw without basal thumblike lobe; hypogenial valve elongate, convex, heavily sclerotized medially, posterior end touching each other, space between valves rhomboid. Male, claw with basal thumblike lobe; ventral plate keel shaped; gonostylus with 2-3 spinules. Adults and pupa of T. japonensis can be identified by the following combination of characteristics: Adult, antenna with 7 flagellomeres. Female, hypogenial valve broad, posterior end of valve not touching each other; cercus elongate, subquadrate; spermatheca slightly wider and long, round. Male, claw with basal thumblike lobe; gonostylus with 1 spinule; ventral plate flat. Pupa, gill of 16 filaments, arising from 3 swollen stalks; abdominal tergites without spine combs except tergites III and IV with small recurved hooks; terminal spine well developed, wavy shaped.

• Journal of Technology Innovation
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• v.18 no.2
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• pp.33-58
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• 2010

This paper explores the patterns of technological innovation in Korean manufacturing sector in accordance with technology intensity which classifies industries into four sectors; high-technology, medium-high-technology, medium-low-technology and low-technology. Empirical study using Korea Innovation Survey(KIS 2008) data shows that the patterns of technological innovation in Korea exhibits the characteristics of science-based firm described by Pavitt across all industry sectors regardless of the level of technology. On the other hand, overseas studies have found the distinct differences between high-and low-technology sectors; the former is shaped by science-based firm and the latter by supplier-dominated firm. It implies that technological innovation activities in Korea do not reflect the level and/or nature of technology and innovation patterns conform to a single standard of high-technology sector. Further studies on causes and impacts of this inclination would be required for effective technology and innovation policy that fits with the level and/or nature of technology in individual industries.

• Journal of ILASS-Korea
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• v.26 no.3
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• pp.127-134
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• 2021

Fire sprinkler initial spray was analyzed by Large eddy simulation (LES) and Volume of Fluid (VoF) integrated method. The IsoAdvector geometric VoF was used to identify the liquid-gas interface clearly even with the large Courant-Friedrichs-Lewy number. To reduce the computational costs, sector meshes and Adaptive Mesh Refinement up to level 3 were used. Base mesh size was 1 mm, which is roughly equivalent to the initial sprinkler droplet. Top surface radius of boss and deflector size were modified to investigate the effects of sprinkler head design on primary breakup process. When top surface radius of boss was increased, vertical liquid sheet was formed. This phenomenon reduced the sheet breakup radius, sheet thickness and velocity. Due to reduced liquid sheet thickness, a large amount of ligaments was created from the liquid sheet. As a result, there was a dramatic decrease in volume per surface area, indicating an increase in breakup process. Spray pattern viewed in radial direction also changed when top surface radius of boss increased. When top surface radius of boss was increased, a T-shaped pattern was observed while a V-shaped pattern was observed in all other cases. When the deflector size increases, the spray pattern remains V-shaped, even if the top surface radius of boss increased. Further studies on promoting atomization of the water supplied to the lower part of the sprinkler head in the T-shape pattern should be conducted.

• Tribology and Lubricants
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• v.2 no.1
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• pp.61-68
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• 1986

Effects of the ram-pressure on the THD-performance of pivoted pad thrust bearings are investigated experimentally. A sector-shaped tilting pad thrust bearing and a rotating disk are used. Temperature distribution on the disk surface as well as on the pad surface, distribution of the pressure generated within the fluid film, and the film thickness are measured continuously in the circumferential direction after thermal equilibrium is established. The ram-pressure is proportional to the mean pressure of oil film and to the rotational speed of the disk and affects the maximum pressure and the pressure distribution. The temperature rise on the mating surface of the disc and the pad, contacting with the oil film, is proportional to to the bearing load and the disk speed. The ram-pressure and the temperature rise on the disk surface are dominant factors that affect the THD-performance of pivoted pad thrust bearings.