• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.589-590
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• 2008

• Digital Contents
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• no.4 s.131
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• pp.28-35
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• 2004

지난해 국내 디지털콘텐츠(DC) 기업들은 DC 시장의 빠른 성장에도 불구하고 많은 부침을 겪어야 했다. 엔씨소프트, NHN, 웹젠, 오위즈 등 각 부문 리딩컴퍼니들은 괄목할만한 성장을 거뒀지만 훨씬 많은 기업들은 매출 부진의 늪에 빠져, 수익감소에 허덕여야 했다. 특히 PC게임 및 애니메이션 기업들은 연이은 흥행실패에 따라 아예 사업구조를 전환하는 등 대안 마련에 부심해야 했다. 상장 · 등록된 기업들을 중심으로 DC기업들의 성적표를 살펴보고, 이들의 2004년 행보를 전망해 봤다.

• The Korean Publising Journal, Monthly
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• s.104
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• pp.24-25
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• 1992

지방자치제도가 정착된 사회에서 공공도서관은 지방정부의 책임하에 발전돼 왔다. 즉, 선진국의 도서관들은 시미니들의 적극적인 참여속에 그 지역의 요구에 맞는 프로그램, 건물, 장서 등을 개발할 수 있는 제도적 장치가 마련돼 있어서 관주도적인 획일적인 도서관 운영은 볼 수 없다. 우리도 지자제시대에 걸맞는 제도를 도입해야 한다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.526-529
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• 2009

In this study, we analyze the characteristic of burning classified by a propellant according to a flux of an oxidizer to analyze propellant regression distance in accordance with a thrust control and burning time of hybrid rocket using hybrid combustor of Lab-Scale. To control a flux of an oxidizer, we design flow control system to regulate the mount of opening and shutting of a needle valve by a driving of stepping motor by a combination the needle valve with stepping motor. We derive the relationships between mass flow rate and regression rate according to a propellant through the oxidizer flux change. While doing the thrust control, we estimate regression distance through the oxidizer flux in accordance with thrust and confirm the creditability through the actual thrust control burning experimentation.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.1
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• pp.40-47
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• 2010

In this study, basic research on the thrust control by controling oxidizer mass flow rate of a $GO_2$/PE hybrid rocket is presented. For this purpose, hybrid rocket system including oxidizer flow control system and data acquisition system was developed. To control oxidizer mass flow rate, we used needle valve with stepping motor which was controled by LabVIEW program. During the fundamental experiments, this system managed to follow the pre-programmed (20 N - 10 N - 20 N - 0 N) thrust level.

• Fire Science and Engineering
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• v.17 no.3
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• pp.55-60
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• 2003

This study established analysis theory for flow characteristics prediction of the spray nozzle and predicted discharge and discharge type of the spray nozzle from numerical analysis. It could know that discharge type of the spray nozzle from prediction data determine to position of nozzle and needle, and flow characteristics prediction of the spray nozzle could know that the characteristics according to shape of nozzle and needle is decided. New model of the spray nozzle that can maximize efficiency of fire suppression from flow characteristics and prediction data of the spray nozzle is presented. The result of this study utilize to data necessary to develop new model of the spray nozzle. Also the result of this study wish to contribute to resource technology security of the spray nozzle, technique ripple effect enlargement of same kind industry and technical development activation of fire protection field etc.

• Journal of ILASS-Korea
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• v.21 no.3
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• pp.121-129
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• 2016

The advantages of the common rail fuel injection system architecture have been recognized since the development of the diesel engine. In common rail systems, a high-pressure pump stores a reservoir of fuel at high pressure up to and above 2000 bar. And solenoid or piezoelectric valves make possible fine electronic control over the fuel injection time and quantity, and the higher pressure that the common rail technology makes available provides better fuel atomization. In this study, the direct needle-driven piezo injector was investigated for accomplishing injection pressure of 1800 bar by optimal design by simplification of component and changing number of springs and plates of DPI. It was found that a direct needle-driven piezo injection system features the prototype DPI for passenger vehicle to operate at 1800 bar of injection pressure.

• Journal of Fashion Business
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• v.22 no.1
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• pp.71-81
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• 2018

This study aims at exploring how the existing stereotypes of needlework, which has long been regarded as a tribute to domestic labor and hobbies which are the purview of women, have come into play in the current trend of convergence among various fields, techniques and materials. This research examines these trends based on cases in two categories applied to the fields of art and space use products. In the field of art, it can be seen that needlework is applied in a variety of ways in the overall diffusion of craftivism, which is a way of asserting opinions about politics and societies. In yarn bombing and performance art, not only do needlework experts, but also, artists of other genres, underscore their propensity of carrying out projects that take advantage of the basic principles of needlework and various physical properties. Various needlework projects applied to the space use products showed the tendency to interact with the spectator or the user as a basic element through examples of playscape, which has the function of being used for relaxation and play. The study was able to confirm the tendency of interior products, which are made from needlework to furniture and tableware directly, and the tendency of materials' expansion. Based on this research, we are going to explore the possibilities for diverse new fusion attempts in fashion and textiles, as well as art, craft and design fields, in the future.

• Tribology and Lubricants
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• v.35 no.4
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• pp.237-243
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• 2019

Through this study, we investigate the effects of ultrasonic nanocrystal surface modification (UNSM) technology on the fatigue life of needle roller bearings. The fatigue life of untreated and UNSM-treated needle roller bearings is evaluated using a roller fatigue tester at various contact stress levels under oil-lubricated conditions. We can ascertain that the fatigue life of an UNSM-treated needle roller bearing was extended by approximately 34.3% in comparison with an untreated one, where the effectiveness of UNSM technology diminishes with increasing contact stress. The surface roughness and surface hardness of needle roller bearings before and after being treated by UNSM technology are compared and discussed to understand the role of UNSM technology in improving the fatigue life of needle roller bearings. In addition, a fractograph of the damaged bearings is observed using a scanning electron microscopy to shed light on the fracture mechanisms of bearings under different contact stress levels. We can therefore conclude that the application of UNSM technology to the needle roller bearings improves the fatigue life by reducing the friction coefficient and increasing the wear resistance; this may be attributed to a reduction in surface roughness from 0.5 to $0.149{\mu}m$ and an increase in surface hardness from 58 to 62 HRc.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.2 s.31
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• pp.59-66
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• 2004

This paper presents a novel fabrication process for a tapered hollow metallic microneedle array using backside exposure of SU-8, and analytic solutions of critical buckling of a tapered hollow microneedle. An SU-8 meta was formed on a Pyrex glass substrate and another SU-8 layer, which was spun on top of the SU-8 mesa, was exposed through the backside of the glass substrate. An array of SU-8 tapered pillar structures. with angles in the range of $3.1^{\circ}{\sim}5^{\circ}$ was formed on top of the SU-8 mesa. Conformal electrodeposition of metal was carried out followed by a mechanical polishing using a pianarizing polymeric layer. All organic layers were then removed to create a metallic hollow microneedle array with a fluidic reservoir on the backside. Both $200{\mu}m\;and\;400{\mu}m$ tall, 10 by 10 arrays of metallic microneedles with inner diameters of the tip in the range of $33.6{\sim}101\;{\mu}m$ and wall thickness of $10{\mu}m\;-\;20{\mu}m$ were fabricated. Analytic solutions of the critical buckling of arbitrary-angled truncated cone-shaped columns are also presented. It was found that a single $400{\mu}m$ tall hollow cylindrical microneedle made of electroplated nickel with a wall thickness of $20{\mu}m$, a tapered angle of $3.08^{\circ}$ and a tip inner diameter of $33.6{\mu}m$ has a critical buckling force of 1.8 N. This analytic solution can be used for square or rectangular cross-sectioned column structures with proper modifications.