• 기술혁신연구
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• 제12권2호
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• pp.67-97
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• 2004

Practical experience with technology implementation of the upgrading of very small village industries in India suggests that innovation failures are not merely a result of the lack of proper interaction between the users and suppliers of technologies under implementation, but also a result of adoption of the primitive conception of competitiveness in their practice of technology development. The approach of promoting the small producers to become individually competitive by using labour intensive, small-scale intermediate technologies is proving to be totally inadequate for the achievement of technological efficiency in a dynamic sense. Guided by a primitive notion of competitiveness, the suppliers of intermediated technologies are thus being led into limiting their technological efforts in the sectors of direct interest to the rural industrial clusters to the transitional objectives of mainly poverty alleviation. Consequently they have not been able to target the small producers of these village industries for the objectives of business growth. This paper posits that under competitive conditions the self-employed small producer has not only to come together for access to resources, but also has to emerge as a multi-sectoral collective of producers, co-operating in production. With the aim to draw lessons that are generic and have policy implications for the development of innovation systems for local economy based rural industrial clusters and value chains, the author analyses in this paper the experience of innovation in technological systems for the sectors of leather, fruits and vegetable processing and agro processing by the People's Science Movement with the help of the Ministry of Science and Technology and other sectoral ministries in India where rural poor were required to pool the resources and capabilities for raising the scale and scope of their collective production organization.

• Structural Engineering and Mechanics
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• 제84권3호
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• pp.375-391
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• 2022

This paper discussed and analyzed the interfacial stress distribution characteristic of adjacent cracks in Carbon Fiber Reinforced Polymer (CFRP) plate strengthened concrete slabs. One un-strengthened concrete test beam and four CFRP plate-strengthened concrete test beams were designed to carry out four-point flexural tests. The test data shows that the interfacial shear stress between the interface of CFRP plate and concrete can effectively reduce the crack shrinkage of the tensile concrete and reduces the width of crack. The maximum main crack flexural height in pure bending section of the strengthened specimen is smaller than that of the un-strengthened specimen, the CFRP plate improves the rigidity of specimens without brittle failure. The average ultimate bearing capacity of the CFRP-strengthened specimens was increased by 64.3% compared to that without CFRP-strengthen. This indicites that CFRP enhancement measures can effectively improve the ultimate bearing capacity and delay the occurrence of debonding damage. Based on the derivation of mechanical analysis model, the calculation formula of interfacial shear stress between adjacent cracks is proposed. The distributions characteristics of interfacial shear stress between certain crack widths were given. In the intermediate cracking region of pure bending sections, the length of the interfacial softening near the mid-span cracking position gradually increases as the load increases. The CFRP-concrete interface debonding capacity with the larger adjacent crack spacing is lower than that with the smaller adjacent crack spacing. The theoretical calculation results of interfacial bonding shear stress between adjacent cracks have good agreement with the experimental results. The interfacial debonding failure between adjacent cracks in the intermediate cracking region was mainly caused by the root of the main crack. The larger the spacing between adjacent cracks exists, the easier the interfacial debonding failure occurs.

• 한국결정성장학회지
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• 제31권6호
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• pp.270-275
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• 2021

ZnO는 출발물질인 황산아연과 알칼리 침전제인 NaOH와 Na₂CO₃에 의해 생성된 아연 중간생성물의 변이 거동과 결정화 조건에 따라 제조하였다. ZnO 결정화를 위해 아연 중간생성물인 Zn₄(OH)₆SO₄·H₂O, Zn₅(OH)₆(CO₃)₂·H₂O를 각각 400℃, 800℃에서 1시간 하소하였고, 하소 온도는 열중량 분석을 기반으로 하였다. 아연 중간생성물인 Zn₄(OH)₆SO₄·H₂O은 400℃에서 Zn₄(OH)₆SO₄·H₂O, ZnO 결정상이 혼재됨을 확인하였고, 800℃에서 완전히 열분해되어 순수한 ZnO만 형성되었다. Na₂CO₃와 반응하여 생성된 아연 중간생성물인 Zn₅(OH)₆(CO₃)₂·H₂O는 400℃ 이상에서 완전한 ZnO의 결정상을 확인하였다. Na₂CO₃와 반응을 통해 상대적으로 낮은 하소 온도에서 나노 입자의 ZnO를 합성할 수 있었다.

• 한국터널지하공간학회 논문집
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• 제22권2호
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• pp.171-183
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• 2020

이 연구의 목적은 대심도 복층터널 Test Bed 구조물에 대한 슬래브의 사전 구조안전성 평가를 통해 슬래브의 가설시와 공용하중 작용시에 발생 가능한 문제점과 개선점을 미리 분석하는 것이다. 대심도 복층터널의 설계 및 시공기술개발의 성과물을 Test Bed 구축을 과정을 통해 검증하고 확인할 수 있으며, 엔지니어 및 일반인들의 학습현장으로도 활용할 수 있어 지하공간 개발의 시기를 더욱 앞당길 수 있는 계기가 마련될 것이다. 특히, 원형의 대심도 복층터널 단면 내부에 구축되는 슬래브는 시공방법과 사용하는 시공장비에 따라 설계하중이 달라지며, 이번 Test Bed 구조체는 그 내부에 상부 슬래브 및 풍도슬래브를 전용 가설장비를 이용하여 설치하는 동안 가설장비하중과 상·하부 슬래브에 공용하중으로 가정된 KL-510의 3등급 트럭하중을 하중조합별 작용위치를 달리하며 상·하부 슬래브에 각각 재하하여 그 영향을 분석하였다.

• 한국세라믹학회지
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• 제44권2호
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• pp.124-131
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• 2007

In this study, first the ADU gel particle, an intermediate for final $UO_2$ kernel of a HTGR nuclear fuel, was prepared from sol-gel method using the broth solution which was made by mixing of the uranyl nitrate, poly vinyl alcohol and tetra-hydrofurfuryl alcohol. The prepared dried-ADU gel particles were converted to the $UO_2\;via\;UO_3$ from thermal treatment with the 4% $H_2$ atmosphere. The sizes of the spherical liquid droplets appeared $1900{\sim}2100{\mu}m$, and the harmony between the flow rate of the broth solution and the frequency and the amplitude of a vibrating system are important factors for the spherical ADU gel particles via the mono size spherical droplets. From the XRD and FT-IR analyses, the prepared ADU gel particles were judged to be a $UO_3{\cdot}xNH_3{\cdot}yH_2O$ form, and the most important factor during the thermal treatment of the dried-ADU gel particle must be avoided a rapidly heating rate in the range of $180{\sim}400^{\circ}C$, and the heating rate should be kept below $5^{\circ}C/min$.

• 방사성폐기물학회지
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• 제6권4호
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• pp.329-346
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• 2008

중저준위 방사성폐기물의 영구처분을 위하여 건설되는 월성원자력환경관리센터의 1단계 폐쇄후 안전성평가에 대하여 기술하였다. 처분시설의 건설운영허가를 위하여 작성된 안전성평가에 대하여 평가개요, 처분시설의 폐쇄개념, 처분부지에 대한 지하수 유동특성을 이용하여 평가를 위한 시나리오의 개발과정과 도출된 평가대상 시나리오에 대한 개념을 기술하였다. 폐쇄후 안전성평가 모델링을 위한 평가도구, 입력인자와 개별 시나리오에 대한 핵종누출 모델링, 기체발생 및 기체이동 모델링, 인간침입 모델링과 생태계 모델링에 대하여 기술하였다. 처분시설의 폐쇄후 안전성 평가시나리오에 대하여 국내 규제치를 만족하는 것으로 평가되었으며 향후 처분시설 안전성에 대한 불확실성 저감과 신뢰성 증진을 위한 노력을 지속적으로 수행할 예정이다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권5호
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• pp.2427-2445
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• 2016

In contrast to traditional "store-and-forward" routing mechanisms, network coding offers an elegant solution for achieving maximum network throughput. The core idea is that intermediate network nodes linearly combine received data packets so that the destination nodes can decode original files from some authenticated packets. Although network coding has many advantages, especially in wireless sensor network and peer-to-peer network, the encoding mechanism of intermediate nodes also results in some additional security issues. For a powerful adversary who can control arbitrary number of malicious network nodes and can eavesdrop on the entire network, cryptographic signature schemes provide undeniable authentication mechanisms for network nodes. However, with the development of quantum technologies, some existing network coding signature schemes based on some traditional number-theoretic primitives vulnerable to quantum cryptanalysis. In this paper we first present an efficient network coding signature scheme in the standard model using lattice theory, which can be viewed as the most promising tool for designing post-quantum cryptographic protocols. In the security proof, we propose a new method for generating a random lattice and the corresponding trapdoor, which may be used in other cryptographic protocols. Our scheme has many advantages, such as supporting multi-source networks, low computational complexity and low communication overhead.

• 한국식품과학회지
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• 제4권4호
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• pp.265-270
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• 1972

혼성육(混成肉)을 원료(原料)로 한 IM식품(食品)을 제조함에 있어서 그 제조조건(製造條件)을 확립(確立)하고 제품(製品)의 효과 기호성(嗜好性) 및 저장성(貯藏性)을 검토하였다. 즉 마쇄(磨碎)한 오징어와 돈육(豚肉)의 혼성육(混成肉)(1 : 1)을 조미성형(調味成型)하여 간장에 20분간 끓이고, $80^{\circ}C$로 가온(加溫)한 glycerol에 20분 동안 담근다음, $60^{\circ}C$에서 70분간 열풍건조(熱風乾燥)함으로써 부드럽고 기호성이 좋은 제품(製品)을 얻을 수 있었다. 본(本) 시제품(試製品)을 polyethylene(0.05 mm). polypropylene(0.05 mm) 및 Al foil에 각각 포장한 후 $37^{\circ}C$, 포화습도(飽和濕度)의 incubator에 42일간 저장하는 동안에 총균수(總菌數)는 1 g당 230에서 각각 40, 20 및 10으로 감소하였고 같은 조건으로 6개월간 장기 저장한 시료도 마찬가지로 감소경향을 나타내었으며 그 내용물은 식용(食用)함에 있어서 새로 만든 제품에 비하여 손색이 없었다.

• 대한치과기공학회지
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• 제39권1호
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• pp.43-52
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• 2017

Purpose: Physical and chemical properties of gold is most suitable to be restored of teeth to its original state. Recently zirconia was used instead of gold because of esthetical and intimacy of human body. Because of high strength and high abrasion resistance of zirconia, all zirconia artificial tooth lead to wear the original tooth of opposite site. To preserve this original tooth, zirconia artificial tooth covered with dental ceramic glass was used. When joining the zirconia core and dental ceramic glass, difference of their thermal expansion coefficient and wetting ability is generated the residual stress at interface lead to crack. In order to solve this problem, intermediate layer what is called zir-liner was imported to decrease the residual stress and increase the bonding strength. Methods: In this study, to identify the optimum conditions for manufacturing process, various methods to rough the surface of zirconia core were adopted, and vary the thickness of interlayer, and analyzed bond strength. Results: Bond strength of sanding specimens group showed higher than that of non-sanding specimens group, and once applied intermediate layer with sanding specimens showed highest bond strength with 28 MPa. SEM photomicrographs of zirconia cores fired at $1500^{\circ}C$ showed parallel straight lines in sanding and pockmarked surface in blasting surfaces as abrasion traces. Observation of the destruction section after shear test by SEM were carried out. Liner applied non-sanding group and non-liner applied sanding group all showed interfacial crack. Sandblasting group with non-liner showed remained dental ceramic glass on the surface of zirconia. Sandblasting group with once applied liner showed partially remained liner and dental ceramic glass on the surface of zirconia. XRD analysis revealed that sandblasting group showed higher monoclinic peaks than other specimens group and this result was due to the high collision energy for stress induced phase transformation. Conclusions: A study on the improvement of bonding strength between zirconia and dental ceramic glass steadily carried out for the future to practical use.

• 대한방사선기술학회지:방사선기술과학
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• 제46권2호
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• pp.151-157
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• 2023

The purpose of this study was to develop an assist device that could correct and support patient position during biopsy on computed tomography (CT) using 3D printing technology. The development method was conducted in the order of 3D design, 3D output, intermediate evaluation for product, final assist device evaluation. The 3D design method was conducted in the order of prior research data survey, measurement, primary modeling, 3D printing, output evaluation, and supplementary modeling. The 3D output was the 3D printer (3DWOX 2X, Sindoh, Korea) with additive manufacturing technology and the polylactic acid (PLA) materials. At this time, the optimal strength was evaluated to infill degree of product as the 3D printing factors into 20%, 40%, 60%, and 80%. The intermediate evaluation and supplementation was measured noise in the region of interest (ROI) around the beam hardening artifact on the CT images. We used 128-channel MDCT (Discovery 75 HD, GE, USA) to scan with a slice thickness of 100 kVp, 150 mA, and 2.5 mm on the 3D printing product. We compared the surrounding noise of the final 3D printing product with the beginning of it. and then the strength of it according to the degree of infill was evaluated. As a result, the surrounding noise of the final and the early devices were measured at an average of 3.3 ± 0.5 HU and 7.1 ± 0.1 HU, respectively, which significantly reduced the noise of the final 3D printing product (p<0.001). We found that the percentage of infill according to the optimal strength was found to be 60%. Finally, development of assist devices for CT biopsy will be able to minimize artifacts and provide convenience to medical staff and patients.