• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.231-237
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• 2005

The sizes and structure of micelles and vesicles formed in ammonium dodecyl sulfate (ADS)/octadecyl trimethyl ammonium chloride (OTAC) mixed aqueous solutions were analyzed by small-angle neutron scattering. In micellar regions of pure ADS and OTAC aqueous solution, the spherical micelles were formed at given concentrations and their sizes were 40 and $61{\AA}$, respectively. The structure transition of pure micelles occurred above 300 mM due to the constancy of the intermicellar distance above 250 mM. The coexisting region of mixed micelles and vesicles in phase diagram of mixed system was also assured. It was investigated that vesicle formed spontaneously took a bilayer structure. The lamellar thickness of vesicles decreased with increasing concentration of vesicle samples. However, the size could not be determined for mixed micelle and vesicle above 100 nm due to limitation of low q ranges. Finally, The 9 mM solution of ADS mole fraction 0.9 (${\alpha}$=0.9) showed bilayer structure compared to phase diagram classified into mixed micelle.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2007.12a
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• pp.173-175
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• 2007

부산신항 남컨 배후지준설토 투기장은 국제도시 부산의 관문이 될 부산신항만 입구부에 위치한 관계로 아름답고 튼튼한 호안이 될 수 있도록 하고, 입찰안내서에 제시된 호안법선변경 금지, 호안마루높이 DL.(+)7.50m 유지 조건을 준수하면서 최적의 구조물이 되도록 하였다. 본사업지는 지형적 특성상 복잡한 형태의 고파랑 작용으로 수리학적으로 월파, 반사파, 연파를 제어하는 경사호안 구조물을 도입하였고, 초연약지반이 대심도로 분포하는 특성을 고려하여 개선된 S.C.P 연약지반 처리공법을 적용하여 기초굴착 없는 친환경적이고 배수기능을 향상시킨 융기토 유용형 S.C.P공법을 적용하였다. 호안전구간은 친수개념을 도입하였으며, 호남도 주변 해양생태계 보호를 위하여 미티게이션(mitigation) 개념을 도입하여 환경복원 계획 및 생태형 친수호안을 구상하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.31-33
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• 2003

현재 국외에서는 산업계 및 학계를 중심으로 기존의 IPv4와 연동 가능한 IPv6에 대한 연구를 추진하고 있다. 또한 국내에서도 IETF의 표준화 기술을 중심으로 몇몇 기관에서 고정망 중심의 IPv6 전이 메커니즘을 구현하고 있다. 그러나 연동 기술에 대한 연구가 고정망에 중심을 두고 있어 이동망에서의 연동 구조에 대한 연구는 부족한 현실이다. 이와 같이 국내외적으로 IPv6망에서의 이중 스택 구조는 고정망을 기반으로 연구가 진행되고 있지만, 이동 인터넷 환경에서의 전이 메커니즘에 대한 연구는 부족한 실정이다. 따라서 본 논문에서는 이동 인터넷 환경에서의 전이 메커니즘에 대한 시나리오 제안과 요구사항 분석을 하고, 절기서 제안된 메커니즘들 중 6to4에 이동성을 적응했을 때의 성능 측정 결과를 제시한다

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.3
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• pp.11-18
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• 2018

Due to the recent overpopulation of urban cities, land shortage and soaring land prices have caused an increase in the demand for high-rise buildings. To build buildings on a limited land, the size of the building is important. Displacement control by horizontal loads in a skyscraper is critical to securing stability and usability of structures. Several systems have been proposed for efficient horizontal displacement control, and so far the study continues. Among them, the Outrigger System is a representative of the typical horizontal load resistance system. Although studies have been conducted so far to locate the optimal position of the outrigger, studies of the slenderness ratio of the buildings are still insufficient. Based on the Outrigger-Optimized Position equation, this study induces the calculation of the displacement of the outrigger installation building according to the slenderness ratio.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.2
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• pp.351-358
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• 1993

Recently a high speed spindle system for machine tools has attracted considerable attention to reduce the machining time, to improve the machining accuracy, to perform the machining of light metals and hard materials and to unite the cutting and grinding processes. In this study, a high speed spindle system is developed by applying the oil-air lubrication method, angular contact ball bearings, injection nozzles with dual orifices and so on. And a lubrication experiment for evaluating the performance of the spindle system is carried out. Especially, in order to establish the lubrication conditions related to the development of a high speed spindle system, the effects of oil supply rate, rotational spindle speed and so on are studied and discussed on the bearing temperature rise, bearing temperature distribution and frictional torque. And the effect of spindle system structure on the bearing temperature distribution is investigated.

• Korean Journal of Materials Research
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• v.8 no.6
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• pp.484-492
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• 1998

The formation mechanism of the epitaxial cobalt silicide from Co/Ti/OOO) Si structure has been investigated. The transition temperature of CoSi to CoSi, was found to increase with increasing the Ti interlayer thickness, which may be owing to the occupation of the tetrahedral sites by Ti atoms in the CoSi crystal structure as well as the blocking effect of the Ti interlayer on the diffusion of Co. Also, the Co- Ti-O ternary compound formed at the metal! Si interface at the begining of silicidation, which seems to play an important role in epitaxial growth of Co silicide. The final layer structures obtained after a rapid thermal annealing of the Cot Ti/( 100) Si bi-layer structure turned out to be Ti oxide/Co- Ti-Si/epi-$CoSi_2$/OOO)

• Korean Journal of Materials Research
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• v.8 no.2
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• pp.165-172
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• 1998

Epitaxial ultrathin films of $CoSi_2$ and double heteroepitaxial structure of Si/$CoSi_2$/Si(lll) were prepared on Si(111)-$7\times{7}$ substrate by in situ solid-phase epitaxy in a ultrahigh vacuum(LHV). The phase, chemical composition, crystallinity, and the microsructure of the Si/$CoSi_2$/Si(lll) interface were investigated by 2-MeV $^4He^{++}$ ion backscattering spectrometry, X-ray diffraction, and high-resolution transmission electron microscopy. The growth mode of the Co film was the Stransky-Krastanov type with texture when the substrate temperature was room temperature. A-type $CoSi_2$ ultrathin film was grown by deposition of about 50A Co on Si(ll1)-$7\times{7}$ substrate followed by in situ annealing at $700^{\circ}C$ for 10 min. The matching face relationships were $CoSi_2$[110]//Si[110] and $CoSi_2$(002)//Si(002) with no misorientation angle. The A-type $CoSi_2$/Si(lll) interface was abrupt and coherent. The best epi-Si/epi-$CoSi_2$2(A-type)/Si(lll) structure was obtained by deposition of Si film on the CoSii at $500^{\circ}C$ followed by in situ annealing at $700^{\circ}C$ for 10 min in UHV.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.3
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• pp.15-21
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• 1999

The flow characteristics around KRISO 300K VLCC double-body model have been experimentally investigated in a closed-type subsonic wind tunnel. The local mean velocity and turbulence statistics including turbulent intensity. Reynolds shear stress and turbulent kinetic energy were measured using a x-type hot-wire probe. The measurements were carried out at several transverse stations of the stern and near wake regions. The surface flow was visualized using on oil-film technique to see the flow pattern qualitatively. The flow in the stern and near wake region revealed complicated three-dimensional flow characteristics. The VLCC model shows a hook-shaped wake structure behind the propeller boss in the main longitudinal vortex region. The thin boundary layer at midship was increased gradually in thickness over the stern and evolved into a full three-dimensional turbulent wake.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.2
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• pp.253-264
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• 1998

In this paper, a design method for directional couplers using bilevel microstrip substrates is proposed. This kind of broadside-coupled coupler provides large coupling factors and broadband characteristics which can not be provided by conventional edge-coupled couplers. Physical dimensions needed for design are obtained by numerical analysis of characteristic parameters of the coupler using the least squares residual method, a kind of variational method, and an eigenvalue problem analysis method. A 3[dB] directional coupler is designed by the proposed method at the center frequency of 1 GHz, built, and tested. The validation and accuracy of the method are confirmed by comparing the numerical results with the experimental results.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.47.1-47.1
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• 2010

Mg합금은 모든 구조용 재료 중에서 비강도가 크며 가공성이 가장 우수하여 재료의 실제 적용시에 2차 가공비 측면에서 다른 경량재료에 비해 유리하다. 그래서 경량화를 필요로 하는 최근 산업체의 요구를 충족시킬 수 있는 재료이다. 그러나 마그네슘 합금의 적용이 매우 제한되는 이유는 결정구조가 hcp로서 냉간가공이 어렵고, 강화기구가 석출경화 및 고용강화로 제한되기 때문에 기계적 성질, 즉 강도와 연성이 모두 낮다. 특히 고온에서 기계적 성질이 급격히 저하되기 때문에 구조용 재료로써는 사용이 어렵다. 따라서, 본 연구에서는 고온에서 안정한 MgZn상과 항복강도를 향상시키는 Mg4Ag상의 석출을 보이는 Mg-Zn-Mn-Ag합금의 시효거동 및 미세조직 변화에 대해 검토하고자 하였다. 본 합금의 석출거동, 미세조직 및 경도 변화에 미치는 시효처리의 영향에 관한 연구를 수행하기 위해 Pandat Program을 이용해 열역학적 계산을 통한 상태도 해석 및 석출상을 예측 하였다. 계산된 결과는 DSC실험을 통해 비교 분석함으로써 신뢰성을 확보하였고 미세조직 및 석출상 분석을 위해 OM, SEM 그리고 XRD로 관찰하였다. 또한, 시효처리에 따른 기계적 특성을 분석하기 위해 상온 및 고온 인장시험을 하였고, 인장시험 후 파단면 분석을 통하여 재료의 파괴거동을 분석하였다.