• 기술혁신학회지
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• 제1권2호
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• pp.231-244
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• 1998

The purpose of this analysis is to clarify the direction and nature of the future leading industries in Korea. Existing studies were analyzed in depth and their implications are as follows. Existing studies have not given a careful consideration for the structural adjustment of Korean economy and the atmosphere for the growth of prospective leading industries. In relation to the structural adjustment, the accomplishment of high value-added in existing industries and the promotion for high-tech industries as well as service industries should be the future direction of the future leading industries. In order to create atmosphere for the growth, it is crucial to achieve a social consensus about the nature of the prospective leading industries and is necessary to continue a concrete research on the related industries.

• International Journal of Aeronautical and Space Sciences
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• 제18권2호
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• pp.215-221
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• 2017

An electromagnetic (EM) wave absorber reduces the possibility of radar detection by minimizing the radar cross section (RCS) of structures. In this study, a radar absorbing structure (RAS) was applied to the leading edge of a blended wing body aircraft to reduce RCS in X-band (8.2~12.4GHz) radar. The RAS was composed of a periodic pattern resistive sheet with conductive lossy material and glass-fiber/epoxy composite as a spacer. The applied RAS is a multifunctional composite structure which has both electromagnetic (EM) wave absorbing ability and load-bearing ability. A two dimensional unit absorber was designed first in a flat-plate shape, and then the fabricated leading edge structure incorporating the above RAS was investigated, using simulated and free-space measured reflection loss data from the flat-plate absorber. The leading edge was implemented on the aircraft, and its RCS was measured with respect to various azimuth angles in both polarizations (VV and HH). The RCS reduction effect of the RAS was evaluated in comparison with a leading edge of carbon fabric reinforced plastics (CFRP). The designed leading edge structure was examined through static structural analysis for various aircraft load cases to check structural integrity in terms of margin of safety. The mechanical and structural characteristics of CFRP, RAS and CFRP with RAM structures were also discussed in terms of their weight.

• 한국가시화정보학회지
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• 제19권3호
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• pp.106-114
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• 2021

In the present study, we investigate the flow characteristics of a paraglider canopy with leading-edge tubercles by performing force measurement and surface flow visualizations. The experiment is conducted at Re = 3.3×10⁵ in a wind tunnel, where Re is the Reynolds number based on the mean chord length and the free-stream velocity. The canopy model with leading-edge tubercles has flow characteristics of a two-step stall, showing an earlier onset of the first stall than the canopy model without leading-edge tubercles. However, the main stall angle of the tubercled model is much larger than that of the canopy model without tubercles, resulting in a higher aerodynamic performance at high angles of attack. The delay in the main stall is ascribed to the suppression of separation bubble collapse around the wingtip at high angles of attack.

• 한국항공운항학회지
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• 제14권4호
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• pp.48-59
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• 2006

This Study focused on the process of technology transfer for the aircraft development program by the strategic alliance. Especially, this study showed how the learning firms absorb new technology from the foreign leading company. This case study concludes that teachability, asset specificity, relation capital with partner, information sharing system in organization and knowledge base are key factors for absorbing the new technology from the technology leading partner.

• ETRI Journal
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• 제45권2호
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• pp.267-276
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• 2023

R&D strategies of companies with low and high technological levels are discussed based on the concept of technology convergence and divergence. However, empirically detecting enterprise technology convergence in the distribution of enterprise technology (total productivity increase) over time and identifying key change factors are challenging. This study used a novel statistical indicator that captures the internal technology distribution change with a single number to clearly measure the technology distribution peak as a change in critical bandwidth for enterprise technology convergence and presented it as evidence of each technology convergence or divergence. Furthermore, this study applied the quantitative technology convergence identification method. Technology convergence appeared from the separation of total corporate productivity distribution of 69 IT companies in Korea in 2019-2020 rather than in 2015-2016. Results indicated that when the total technological level was separated from the technology leading and technology catch-up, IT companies were found to be pursuing R&D strategies for technology catch-up.

• 센서학회지
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• 제32권1호
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• pp.10-15
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• 2023

It is well known that polycrystalline ceramics fabricated via the templated grain growth method along a desired crystallographic direction, generally along [001], exhibits enhanced piezoelectric response. Generally, the piezoelectric properties of textured ceramics depend on the degree of texture, as piezoelectric properties peak in single crystals. Therefore, understanding the relationship between the degree of texture and piezoelectric properties is fundamental. Here, we present state-of-the-art textured piezoceramics by focusing on critical issues such as the quality of templates used for texturing and proper evaluation of the degree of texture analysis. The relationship between the degree of texture and its impact on the properties of textured materials is exclusively defined by the Lotgering factor (L.F.) calculated from the X-ray diffraction profiles. Additionally, we show that L.F. is not a suitable indicator of the degree of texture, contrary to previous interpretations. This statement was further supported by the fact that the true degree of texture can be better quantified by the multiples of random distribution. This argument was justified by comparing the quantitative values of the degree of texture obtained from both methods to those of the piezoelectric charge coefficient of textured and random ceramics.

• Journal of Ship and Ocean Technology
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• 제8권2호
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• pp.13-19
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• 2004

Jet flows applied tangential to a foil surface near the leading and/or trailing edges increase the lift of the foil by delaying the separation also known as the Coanda effects. Many experimental and numerical studies have proven the effectiveness of Coanda effects on circulation control and the effects have been found to be useful in practical application in many aerodynamics fields. Most of the previous works have studied the effects of the jet blowing near the trailing edges and investigated the influence of jet momentum on lift. A few experimental studies, however, focused on the separation bubble that develops near the leading edge and applied jet flow the edge to remove the bubble but only to find decrease in lift. In the present paper, a Coanda foil of 20% thickness ellipse with modified rounded leading and trailing edges was investigated, and the flow around the foil was numerically studied. The blowing around the leading edge only decreased the lift, as the experiments showed, but the suction considerably increased the lift.

• Journal of Mechanical Science and Technology
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• 제18권3호
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• pp.481-490
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• 2004

Steady state flow calculations are executed for turbo-pump inducers of modern design to validate the performance of Tascflow code. Hydrodynamic performance of inducers is evaluated and structure of the passage flow and leading edge recirculation are also investigated. Calculated results show good coincidence with experimental data of static pressure performance and velocity profiles over the leading edge. Upstream recirculation, tip leakage and vortex flow at the blade tip and near leading edge are main sources of pressure loss. Amount of pressure loss from the upstream to the leading edge corresponds to that of whole pressure loss through the blade passage. The viscous loss is considerably large due to the strong secondary flow. There appears more stronger leading edge recirculation for the backswept inducer, and this increases the pressure loss. However, blade loading near the leading edge is considerably reduced and cavitation inception delayed.

• 한국산학기술학회논문지
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• 제22권1호
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• pp.214-220
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• 2021

소형 무인 지상 차량은 폭발물 제거 작전, 대테러 작전, 화재 진화 및 소방정찰, 재해·재난지역 정찰 및 접적 지역 감시 등의 위험한 임무를 수행하기 위해 사용되고 있다. 기술 선도국인 미국, 영국, 프랑스, 독일, 이스라엘 등에서는 군사 분야뿐만 아니라 민간 분야에서 활용하기 위해 다양한 무인 지상 차량을 개발하여 운용하고 있다. 개발된 체계는 실 운용 과정에서 수집된 데이터와 연관된 추가 요구사항을 기반으로 더욱 업그레이드되고 있으며, 향후 소형 무인 지상 차량 개발에 있어 기술 선도국의 개발 동향은 중요한 지표로 활용될 수 있다. 본 연구에서는 기술 선도국에서 운용 중인 소형 무인 지상 차량의 개발 동향 및 임무를 분석하였다. 군사 및 민간 분야에서 다양한 임무를 수행하고 있는 소형 무인 지상 차량을 대상으로 체계에 적용된 정찰 능력, 특수기능 등의 능력과 다양한 임무 형태에 따른 체계 운용 목적을 분석하였다. 기술 선도국의 소형 무인 지상 차량 개발 동향을 토대로 향후 군사 및 민간 분야에서 소형 무인 지상 차량 개발에 필요한 기능 및 설계 특성에 대해 논한다.

• 농촌지도와개발
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• 제13권2호
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• pp.277-286
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• 2006

The study aims at analysing the practical effects of "blended learning system" and participatory research methodology. The business programs are running by RDA. Even though many leading farms have been tried on binding technology and agribusiness, however business of farms in Korea are still in the beginning stage. The business program for leading farms of RDA is not only education program but also participatory research program. This program consist of on-line and off line, seminar and business homework etc. The main results of this paper are as follows: 1) to make organization of farms to accomplish business goals 2) to find out solution for urgent problems and subjects of farm management 3) to construct system for leading farms and on-line communities 4) to practice profitable business model for leading farms. Farms needs are not only technology transference, but business model for success of farm management.