• Journal of the Korean Wood Science and Technology
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• 제18권2호
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• pp.36-48
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• 1990

This experiment was carried out to improve the quality of high absorbent polymer which has excellent absorptivity and water retention compared to pulp and absorption sheet, through absorption characteristics-absorptive power, water retention, absorption rate, gel strength, pH, particle size, and moisture content. - of six polymers, namely, anionic polyacrylamide, cationic polyacrylamide, polyacrylic, acid polyvinyle alcohol 500, and 1500, and a-cellulose. and to examine the possibility of substitution of amide groups for carboxyl group and/or hydroxyl group which were commercial high absorbent polymer by comparing the absorption characteristics of the polymers. Polyacrylamide has high absorptive power and water retention, but has low gel strength and poor absorption rate. The rest of polymers were similiar to ${\alpha}$-cellulose in every respect. Thus, polyacrylamides could be replaced with polyacrylic acid and polyvinyl alcohol which are presently a high absorbent polymers. In comparing the absorption characteristics and the absorptive power of the polymers-anionic polyacrylamide, cationic polyacrylamide, polyacrylic acid, polyvinyle alcohol. a-cellulose-the absorptive power was in inverse proportion to the gel strength and absorption rates, affected by the particle size and pH change.

• 한국소음진동공학회논문집
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• 제14권8호
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• pp.668-674
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• 2004

The possibility of global noise reduction by the sound power control through selection of distribution and impedance of absorptive materials is discussed. It is necessary to investigate the relation between the global sound energy in the field and the total sound power radiated by sources. In the previous work,$^{(1.2)}$ the authors presented a useful design method to change boundary condition that can be useful to reduce noise in acoustically small enclosures. Changing boundary condition Is related to not only enclosure’s geometrical shape but also acoustical treatment on walls for example, attaching of impedance patches (ex: absorptive material). In many practical situations, we often meet situation to change acoustical treatment on walls. The possibility of total acoustic potential energy(globa1 noise) reduction by acoustic source power control is examined in an acoustically small cavity Using acoustic energy balance equation, the relation between global noise control performance and absorptive material’s arrangement/impedance is deduced. Numerical simulation is performed to interpret its physical meaning in terms of absorbent’s distribution and impedance.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.688-691
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• 2004

We have studied the possibility of global noise reduction by the sound power control through selection of distribution and impedance of absorptive materials. It is necessary to investigate the relation between the global sound energy in the field and the total sound power radiated by sources. In the previous work (1,2), the authors presented a useful design method to change boundary condition that can be useful to reduce noise in acoustically small enclosures. The possibility of total acoustic potential energy reduction by acoustic source power control is examined in an acoustically small cavity. Using acoustic energy balance equation, the relation between global noise control performance and absorptive material's arrangement/impedance is deduced. Numerical simulation is performed to interpret its physical meaning in terms of absorbent's distribution and impedance.

• 반도체디스플레이기술학회지
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• 제16권4호
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• pp.36-40
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• 2017

With an attempt to enhance the visibility of laser beam, we have investigated a black matrix with scattering particles by ray tracing simulations. As the scattering particle density is increased, the detected power by the receiver is increased, thereby enhancing the visibility. In reality, the visibility is reduced with increasing incident angle (away from the normal incidence) of laser beam, a phenomenon also observed by ray tracing simulations. It is due to the fact that the mean path is increased within a highly absorptive BM layer or a smaller number of rays hit the BM area when the incident angle is high. Embedding a number of scattering particles into BM may bring in crosstalk among pixels. However, it is negligible because scattered rays inside highly absorptive BM are re-scattered due to the high scattering particle density, decreasing the power of scattered rays into the active areas.

• 기술경영경제학회:학술대회논문집
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• 기술경영경제학회 1999년도 제15회 하계 학술발표회 논문집
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• pp.176-202
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• 1999

Korea has exerted her efforts to assimilate nuclear power technology, and reportedly localized 95 percent of nuclear power technology by 1995. This paper investigates the evolution of nuclear power program in Korea to exploit the development process of the nuclear power industry and key factors for the technological localization of nuclear power plant. In developing countries, an imitative catching-up process can be shown as a course for developing the absorptive capacity of foreign technology, which depends on prior knowledge base and the intensity of effort. The process of technological learning consists of five stages including preparation, implementation of foreign technology, acquisition of peripheral technology, acquisition of core technology, and improvement f foreign technology. Moreover, this paper discusses six essential factors that have influenced the successful achievement of technological localization of nuclear power plants in Korea. They include the role and strategies of the government, the leading role of utility firm, the development and cooperation of the related organizations, the development of human resources and their efforts, market conditions and the assistance of foreign donors, and social conditions. Finally, this paper discusses about implications offered by the Korean experience for other developing countries.

• Journal of Power Electronics
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• 제16권6호
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• pp.2221-2230
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• 2016

Voltage and frequency stability issues occur in existing centralized power system due to the high penetration of renewable energy sources, which decrease grid absorptive capacity of them. The grid-connected inverter that mimics synchronous generator characteristics with inertia characteristic is beneficial to electric power system stability. This paper proposed a novel three-phase four-wire grid-connected inverter with an independent neutral line module that mimics synchronous generators. A mathematical model of the synchronous generator and operation principles of the synchronverter are introduced. The main circuit and control parameters design procedures are also provided in detail. A 10 kW prototype is built and tested for further verification. The primary frequency modulation and primary voltage regulation characteristics of the synchronous generator are emulated and automatically adjusted by the proposed circuit, which helps to supports the grid.

• 한국생산제조학회지
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• 제9권2호
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• pp.66-71
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• 2000

Laser induced surface hardening of Tool steel(STC5) can be achieved either with or without surface melting. In trans-formation hardening as the surface is heated to a temperature below its melting point and is rapidly cooled solidified microstructures are usually much finer and stronger than those of the base matals. For this reason surface modification of tool steel by YAG laser irradiation has been studied as a function of processing parameters such as power density pulse width defocusing distance and molten depth. The high energy density changes and refines the microstructure of the near surface layer. In the case of beam passes martensite formed in the melt zone exhibited very high vickers hardness values. Molten depth and width depend on defocusing distance and energy of black color painting is more absorptive than other color painting.

• 한국음향학회지
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• 제6권2호
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• pp.54-61
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• 1987

실험실이 아닌 일반음장에서 음향인텐시티법을 이용하여 공조덕트 소기기의 감음성능 평가방법을 검토하였다. 음향인델시티법에 의한 감음량 측정치는 음압법에 의한 측정치보다 이논치와 비교적 잘 일치하였으며, 음향인텐시티법은 음압법에 비하여 음장조건에 따른 영향을 비교적 적게 받는 것으로 나타났다.

• 한국전자파학회논문지
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• 제13권5호
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• pp.451-458
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• 2002

6-18 GHz 주파수대역에서 사용되는 흡수형의 SP3T 및 SP8T 스위치 모듈을 설계 및 제작하였다. 스위치 모듈에 사용된 MMIC 칩의 에피구조는 저 손실과 고 전력용으로 설계되었다. 최대입력전력은 SP3T 스위치 모듈이 2 W이고 SP8T 스위치 모듈이 1 W이다. 200 nsec의 고속 스위칭을 위한 구동회로를 모듈에 내장하였다. 모듈의 최대삽입손실은 SP3T 및 SP8T에 대해 각각 2.8 dB, 4.2 dB로 측정되었다. 입ㆍ출력포트간 분리도는 모두 55 dB 이상을 얻을 수 있었다. 두 스위치 모듈은 전자전 시스템에 적용하기 위한 관련 환경시험을 모두 통과하였다.

• 한국벤처창업학회:학술대회논문집
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• 한국벤처창업학회 2007년도 춘계학술대회
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• pp.35-64
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• 2007

중소기업의 기술혁신 역량을 강화하기 위한 각종 정부 정책과 투자의 지속적인 확대에도 불구하고 우리나라의 산학연 협력 수준은 선진국에 비해 아직도 상당히 미홉한 것으로 평가되고 있다. 또한 기술혁신성과에 영향을 미치는 기업 내부요인에 대해 다양한 요인이 제시되고 있지만, 산학연 기술협력과 기술혁신성과 간의 관계에 대한 기존 연구에서는 산학연 기술협력과 성과 간의 직접적인 영향(상관)관계만을 고려하고 있으며, 기업 내부요인들에 의해 그 효과가 어떻게 달라지는지는 분석하고 있지 않다. 따라서 본 연구에서는 산학연 기술협력이 중소기업의 기술혁신 성과를 높이기 위해서 어떤 중소기업을 지원해야 하며, 증소기업들이 어떤 내부적인 노력을 해야 하는가를 우리나라 증소제조업을 대상으로한 실증분석을 통해 규명하고자 한다. 분석 결과, 산학연 기술협력과 흡수 능력 중 혁신적 인적자원관리 시스템이 기술혁신성과에 정(+)의 영향을 끼쳤다. 또한 산학연 기술협력과 혁신적 인적자원관리 시스템 간에 정(+)의 상호작용 효과가 존재하는 것으로 나타났다. 이 연구는 정책적으로 산학연 기술지원을 할 때 기업의 기술개발강도만을 갖고 판단할 것이 아니라 기업 내부적으로 혁신 창출을 위한 노력, 즉 혁신적 인적자윈관리 시스템이 갖추어져 있는지 고려해 볼 필요가 있음을 시사한다. 경영 측면에서는 중소기업에 내부 자원과 능력의 한계가 존재하므로 외부자원을 충분히 활용함으로써 기술혁신성과를 높이는 것이 중요하다는 시사점을 제공한다.