• Journal of Environmental Science International
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• v.4 no.5
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• pp.387-402
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• 1995

An attempt was made to study the subdivision of Korea by the annual amount and the annual change pattern of monthly precipitation days(that is one of the important elements of the precipitation characteristics), using the mean values for the years 1961-1990 at the 68 stations. The amplitudes of annual change were normalized and using these values, the principal component analysis was applied to determine the annual change patterns. The results show that they are expressed by the combinations of the three change patterns in almost whole regions of Korea. As a result, the annual change pattern of precipitation days in Korea is classified into 8 types from A to e, in detail, 36 types from A0 to e$\circled2$.And regional division of precipitation days in Korea is divided into 13 regions from I a to IIIC, into detail, 41 regions from I no to IIICl.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.2
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• pp.52-59
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• 1993

This study is investigated of tensile and fatigue strength for advanced composite materials under hygrothermal environment. The materials used are two types of Carbon/Epoxy reinforced composite materials i.e., 13$0^{\circ}C$ cure-type composite T-1/347, and 18$0^{\circ}C$ cure-type MM-1/982X. These are composed by cross-ply laminates. Test condition is the distilled water of 8$0^{\circ}C$. The separate absorption contents estimated by the Fick's diffusion rule are similar to the experiment results. The tensile strength of T-1/347 wet specimens more increased than that of dry ones, but that of MM-1/982X decreased. The fatigue strengthes of both T-1/347 and MM-1/982X wet specimen more decreased than those of dry specimens.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.9
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• pp.1295-1303
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• 1993

We present an 1-out-of-n noninteractive OT(Oblivious Transfer) protocol based on the Diffle-Hellman assumption and a new fair exchange scheme of secret information among multi-users. Using the noninteractive OT protocol and the fair exchange scheme, we also present a new digital multisignature scheme based on Fiat-Shamir signature scheme and analyze its security. Owing to its concurrency, viability, and dishonesty detectablility, the proposed digital multisignature scheme is applicable to electronic multi-user contract systems.

• Proceedings of the KAIS Fall Conference
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• 2006.05a
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• pp.587-592
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• 2006

코팅은 플라스틱의 표면의 물성과 렌즈의 광학적 성능을 높이기 위해 필요하다. Allyl diglycol carbonate계열 렌즈 표면의 물성과 광학적 성능을 개선하기 위하여 3-glycidoxypropyltrimethoxysilane(GPTS), methyltrimethoxysilane(MTMS) 및 tetraethyl orthosilicate(TEOS)의 몰 비를 변화시켜 유-무기 하이브리드 재료로 사용하였다. Sol-gel 공정에 의한 flow코팅하여, $140^{\circ}C$에서 4시간 경화하였다. 코팅 렌즈는 투과율, 부착력, 연필경도, 내마모성, 내온수성 및 내약품성을 평가하였고 GPTS, MTMS 및 TEOS의 몰비가 각각 1: 1: 2일 때 가장 우수한 것으로 나타났다.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.533-536
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• 2005

Drying shrinkage and strength of the redispersible SBR and PAE powder-modified mortars were experimentally investigated. Results of the study that the drying shrinkage rapidly increased until 7 days of age and it was then saturated to the value of about $1\~2\times10^{4}$ after 14 days. It turned out that the polymer-cement ratio exerted more influence on the drying shrinkage than the content of powder shrinkage-reducing agent did. Flexural (compressive) strength of the mortar increased (decreased) as the polymer-cement ratio increased and it was 7$\~$11 (23$\~$39) MPa at 7 days of age. The average (maximum) increasing (decreasing) rate turned out to be about 10 (30) $\%$. As in the drying shrinkage case, the polymer-cement ratio exerted more influence on both flexural and compressive strengths than the content of powder shrinkage agent did.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.537-540
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• 2005

Durability of the polymer-modified mortars using the redispersible SBR and PAE powder-modified mortars were experimentally investigated. Results of a previous study were used to determine the mix proportion that optimized the strength, and the freezing-thawing resistence, the carbonation depth and the chloride intrusion depth of the mortar for various polymer-cement ratios were studied. After 300 freezing-thawing cycles, the rate of weight reduction decreased from 7 to below 2 $\%$ as the polymer-cement ratios increased from 0 to 15 $\%$, and, on the 150 cycle basis, durability index increased from 60 to 98. Carbonation depth decreased from initial value of 5.5 to about 2.5 mm and chloride intrusion depth did from 3.5 to 1.5 mm

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.5
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• pp.35-41
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• 1998

This paper presents a decoupling controller of the missile seeker scan loop with a spin-stabilized platform. A precise seeker motion with respect to the scan command is essential for the higher acquisition probability of the target. As the seeker scan loop is a deeply cross-coupled two input two output system, an accurate pointing or scanning for each axis to the target is very difficult, even though provided with the help of a high performance controller. When a decoupling control is applied to the seeker scan loop, the cross-coupling between two axes can be reduced to a remarkable amount. As a low order of controller is required for the real time operation, a PI controller with decoupling filter is suggested and compared with other controllers. A linearized dynamic model of seeker scan loop is used and validated through the comparison of experimental results of step responses.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.727-730
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• 2004

The purpose of this study is to evaluate the fundamental properties of fine type cement grouts with redispersible polymer powders. Cement grouts with redispersible polymer powders are prepared with various polymer-cement ratios, and tested. for flow, water absorption, drying shrinkage, flexural and compressive strengths. From the test results, flow of the cement grouts with EVA and Va/VeoVa polymer powers decreased with increasing elapsed time. Regardless of polymer type, the flexural strength of the cement grouts tends to increase with increase in polymer-cement ratio. The maximum compressive strengths of the cement grouts are obtained at a polymer-cement ratio of $5\%$.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.106-107
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• 2013

The purpose of this study is to characterize the bonding properties between reinforced bar and re-emulsion polymer cement mortar through the pull off test. The properties of polymer cement mortar before and after hardening were measured. Spiral reinforced steel bar was used to control the brittleness fracture of test specimens. In addition polymer content as experimental factors, the types of reinforced bar and corrosion were considered as well. Non linear FEM analysis was carried out to expect the behavior of bonding interface under the certain load.

• Information and Communications Magazine
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• v.30 no.1
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• pp.33-38
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• 2012

스마트시대는 전 산업분야, 더 나아가 사회 전반에 IT가 활용, 재생산되어 인류 삶의 질을 보다 향상시키는 시대로 정의할 수 있다. 이를 위한 기술(스마트 기술)의 혁신은 타산업과의 융합은 물론, IT산업발전을 위한 총체적(holistic)접근이 요구되며, 단기적이고 금전적인 성과를 지향하기 보다는 비금전적(non-financial)이며, 사회성과 등 미래 성과를 지향하는 특징을 가지고 있다. 본고에서는 스마트시대 기술 진화방향을 생태계(CPND) 활성화 차원에서 조망하고, 혁신을 위한 R&D 전략을 기술도메인의 발굴 및 선택을 위한 기획전략, 효과적 성과창출을 위한 수행전략 그리고 효율성 제고를 위한 성과 활용전략으로 구분하여 제시하였다. 즉, 미래 스마트시대에 부합하는 기술혁신을 견인하기 위해서는 물리적 공간/아날로그적 형식에서 가상(Virtual) 공간/디지털 형식으로, 폐쇄적 플랫폼에서 개방형 플랫폼으로, 음성/데이터중심에서 지능화된 디바이스로, 대인통신에서 사물통신으로 진화하는 메가트렌드를 고려하여, 지향점에 따른 차별적 기획체계 구축, 다양한 가치생성방식의 활용, 성과극대화형 R&D 수행방식 수립, 그리고 특허경영과 같은 활용체계 구축 등의 R&D 전략이 필요함을 제시하였다.