• 공업화학
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• 제8권3호
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• pp.473-481
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• 1997

Videomicroscopy를 이용하여 비이온성 계면활성제 수용액과 oleyl alcohol, oleic acid와 같은 극성 오일을 접촉시켰을 때 일어나는 동적 거동을 관찰하였다. Vertical-stage의 현미경을 사용하여 비이온성 계면활성제 수용액상 위에 동일한 부피의 오일상을 주입하여 두 상을 접촉시켰을 때 일어나는 계면활성들, 특히 detergency 결과에 중요한 영향을 미치는 중간상 형성, 확산에 의한 과포화로 인하여 일어나는 자발적 유화 현상 등을 관찰하였다.극성 오일로 각각 oleyl alcohol과 oleic acid를 사용하여 1wt% $C_{12}E_5$ 수용액과의 동적 거동을 관찰한 결과는 동일한 경향을 나타내었다. 즉 운점보다 낮은 온도 조건에서는 오일상과 계면활성제 수용액상의 상호작용이 거의 없는 것을 관찰할 수 있었으며, oleyl alcohol을 사용하여 운점보다 높은 온도 조건인 $35^{\circ}C$, $40^{\circ}C$, $51.7^{\circ}C$에서 실험한 lamellar liquid crystal이 중간상으로 형성되었고 확산에 의한 과포화로 인한 자발적 유화 현상을 관찰할 수 있었다. 또한 oleyl alcohol 시스템에 대한 개략적인 상 평형도를 이용하여 각 온도 조건에서 oleyl alcohol과 계면활성제 수용액상이 접촉할 때 일어나는 중간상의 생성 및 자발적 유화 현상 등의 동적 현상들을 diffusion path를 사용하여 이해하였다.

• 지질공학
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• 제24권1호
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• pp.23-38
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• 2014

아랍에미리트연합(UAE)의 Ruwais지역 Sabkha층 탄산질 모래는 석영질 모래와는 구성성분이 다르며 낮은 외부하중에서 쉽게 입자파쇄가 발생한다. 이러한 지반은 상부하중으로 인한 입자파쇄를 유발하여 추가 침하가 발생하며 전단강도가 감소하게 된다. 이러한 문제에 대한 구체적인 연구를 위하여 표준압밀시험과 삼축압축시험을 수행하여 탄산질 입자의 파쇄에 대한 다양한 공학적 특성을 분석하고자 하였다. 그 결과 탄산질 모래는 선행입자파쇄 정도에 따라서 파괴시 전단 응력의 크기가 다르게 나타났다. 즉, 응력경로를 나타내는 p-q 다이어그램에서 p' > p인 경우가 발생하였으며, 이때 내부 공극이 외부로 노출되어 음(-)의 간극 수압이 발생되었다. 또한, 입자파쇄로 인하여 증가하던 q값이 감소하였다. 삼축압축시험결과 탄산질 모래의 선행입자파쇄 정도에 따라서 압축시 발생되는 간극수압의 형태가 다르게 나타나 Sabkha층 탄산질 모래의 입자파쇄시 나타나는 다양한 거동특성을 알 수 있다.

• 자원환경지질
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• 제27권2호
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• pp.161-170
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• 1994

Jindong Granites are plotted mainly in the region of granodiorite~diorite of the Streckeisen's diagram, while Yucheon-Eonyang Granites and Onjonri Granites in the region of monzo-granite and monzo-granite~granodiorite, respectively. Jindong Granites show a differenciation trend of calc-alkaline magma, and its magmatic evolution from intermediate to acidic rocks, which might form mineralizing solution, is consistant with the general path of the Cretaceous granitic rocks including Yucheon-Eonyang Granites and Onjongri Granites. The differenciation index (D.I.) is 35~80 for Jindong Granites, which is lower than 85~95 of Yucheon-Eonyang Granites and is partly overlapped by 67~84 of Onjongri Granites. There is clear difference in content of some major and trace elements between Jindong Granites of Cu province and the other granitic rocks of Pb-Zn and Mo provinces. Between these metallogenic provicnes, Cu content is high in Jindong Granites near Haman-Gunbuk mineralized zone, while Pb and Zn are relatively abundant in Yucheon-Eonyang Granites and Mo in Onjongri Granites. Therefore, Jindong Granites of the Cu province are distinguishable by chemical compositions and their related geochemical characteristics from the other Cretaceous granitic rocks of Pb-Zn and Mo provinces. However, the content of Cu and Cl in biotite is applicable to distinguish a productive phase from a barren phase of Jindong Granites, because Cu and Cl show a trend to be concentrated in biotite of Jindong Gratites in the Haman-Gunbuk mineralized zone.

• 소성∙가공
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• 제28권6호
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• pp.368-374
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• 2019

The past recent years have seen an increasing use of high-strength steel sheets in the automotive industry. However, the formability and damage prediction of these materials requires accurate acquisition of necking and fracture strains. Digital image correlation (DIC) is used to accurately capture the necking and fracture strains during testing. The fact that single time points of capturing vary with frame rate makes the need for an investigation necessary. For the high-strength steel DP980, the frame-rate dependences of the final necking and fracture strains values are analyzed here. To eliminate the influence of gauge length, the strains were measured locally by DIC. Results for three specimen shapes obtained with frame rates of 1 and 900 fps (frames per second) were considered and based on them, triaxiality failure diagrams (TFD) are established. It was observed that after diffuse necking, the deformation path departed from the initially linear one, and the stress triaxiality grew with ongoing deformation. It was further revealed that the frame rate-dependence of the necking strain was rather low (< 2%), whereas the fracture strain could be underestimated by up to 8% when the lower frame rate of 1 fps was used (compared with 900 fps). In this study, this issue is investigated while taking into consideration the three different triaxialities. These results demonstrate the importance of choosing an appropriate frame rate for the determination of necking and fracture strains in particular.

• 한국전자파학회논문지
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• 제12권2호
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• pp.308-315
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• 2001

본 논문에서, Feedforward 기법을 이용하여 송신 혼변조 왜곡 신호뿐만 아니라 수신 대역 잡음도 감소시킬 수 있는 새로운 전력 증폭기를 제안했다. 대전력 증폭기는 IMT-2000 기지국 송신 주파수 대역에서 구현되었다. 송신 대역 혼변조 왜곡 신호와 수신대역 잡음 신호는 가변 감쇠기와 위상 천이기, 에러 증폭기의 제어에 의해 감소되어진다. 두 개의 루프, 즉 혼변조 왜곡 신호와 수신대역 잡음 신호제거 루프를 포함하고 있는 제안된 전력 증폭기를 사용하면 송신 대역 통과 여파기의 수신 대역 감쇠 특성을 엄격히 하지 않아도 되어 다양한 무선통신 시스템에서 낮은 송신경로 삽입 손실을 가진 듀플렉서를 제공할 수 있다. 전력 증폭기의 2-tone 실험은 5MHz 주파수 간격을 가진 2.14GHz에서 하였고, 수긴 대역 제거 실험은 중심 주파수가 1.95GHz인 60MHz 수신 전체 대역에서 하였다. 실험 결고, 혼변조 왜곡 제거 성능과 수신 잡음 제거 성능이 각각 31 dB와 21dB이상이었다.

• 자원환경지질
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• 제28권1호
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• pp.53-67
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• 1995

Geochemical characteristics of iron-related Ulsan granite was studied in comparison with the Cretaceous granitoids from the metallogenic provinces of copper, lead-zinc and lead-zinc/molybdenum in the Gyeongsang Basin, and the variation of cheminal compositions at the Ulsan granite/serpentinite contact was investigated. Ulsan granite is plotted in the regions of granite and granodiorite of Streckeisen's diagram. It shows differentiation trend of calc-alkali magma, and the magmatic evolution from granodiorite to granite is consistant with the general crystallization path of the Cretaceous the granitoids in Gyeongsang Basin. Differentiation index(D.I.) of Ulsan granite is 86~95, which is higher than those of Jindong granites (D.I.=45~70) and Onjongri granites (D.I.=67~84), and there are differences in the content of some major and trace elements between Ulsan granite and other Cretaceous granitoids. At the Ulsan granite/serpentinite contact $SiO_2$, $K_2O$, $Na_2O$, $Al_2O_3$, Rb, Sr, Ba which are abundant in Ulsan granite decrease toward serpentinite, while T.Fe, MgO, Ni, Cr which are abundant in serpentinite decrease toward Ulsan granite. Therefore, the geochemical characteristics of Ulsan granite is applicable to distinguish iron province from different metallogenic provinces where other Cretaceous granitoids occur in the Gyeongsang Basin, and it is possible to find serpentinite which was intruded by granite on the basis of chemical variations.

• Architectural research
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• 제9권2호
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• pp.27-35
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• 2007

Our nation has a problem with discrimination of income distribution and inefficient of resources distribution caused by real estate price rising from a sudden economy growth and industrialization. Specially, in recent years, there is a great disparity of apartment price between the north and south of the Han river. Because the housing price is decided by the immanent value of a house and neighborhood effects of the regional where the house is situated, the housing price is occurred difference. The purpose of study was to analyze the influence of various factors of housing price. Also, this study tried to predict real estate market and to establish previous effective real estate policy. In this study, we analyzed the differences of housing price determinants about apartment developments between the north and south of the Han river, and found the important factors that affect the housing price using Structural Equation Modeling(SEM). As a result of this study, the older the buildings are, the more the housing price and the housing price rising ratio have increased, in Gang Nam area. This reason is that these have large possibility to be reconstructed and many convenient facilities, in this area. In the case of Kang Buk area, the increase rate of housing price are so low that they couldn't take effect on the housing price and they were declined. So to speak, constructing the infrastructure which takes effect on the increase rate of housing price is very urgent.

• 항공우주시스템공학회지
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• 제10권4호
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• pp.17-25
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• 2016

본 연구에서는 초점면부 영상안정화 기법 중 렌즈 시프팅 영상안정화 기법에 적용될 광학설계를 수행하였다. 렌즈 시프팅 기법은 광학탑재체로 전달되는 미세진동외란을 보상하기 위해 광 경로를 바꿔주는 영상 안정화 기법이다. 실제 위성카메라의 제원을 참고하여 렌즈 시프팅 기법이 적용될 광학계의 요구도를 수립하였으며, 광학설계 프로그램인 Code-V를 이용해 광학계를 설계하였다. 설계된 광학계가 요구 조건을 충족하였는지 검증하기 위해 시야에 따른 광선 수차분석, 스팟 다이어그램 분석, MTF 선도분석을 수행하였다. 최종적으로 설계된 광학계는 슈미트 카세그라인 타입에 필드 플래트너와 진동보상 렌즈가 삽입된 형태이며, 주반사경 직경은 200 mm, GSD 2.87m, 나이퀴스트 주파수에서 MTF 33%으로 광학계 성능요구도를 만족하였다. 본 연구에서 설계된 진동보상렌즈의 입사광선에 대한 진동계수는 0.95~1.00 으로 성능 요구도를 만족하였다.

• 대한기계학회논문집B
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• 제26권5호
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• pp.742-749
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• 2002

Numerical Study with detailed chemistry has been conducted to investigate the flame structure and NOx formation characteristics in oxygen -enhanced(CH$_4$/O$_2$-$N_2$) and oxygen-enhanced-EGR(CH$_4$/O$_2$-$CO_2$) counter diffusion flame with various strain rates. A small amount of $N_2$is included in oxygen-enhanced-EGR combustion, in order to consider the inevitable $N_2$contamination by $O_2$production process or air infiltration. The results are as follows : In CH$_4$/O$_2$-$CO_2$flame it is very important to adopt a radiation effect precisely because the effect of radiation changes flame structure significantly. In CH$_4$/O$_2$-$N_2$flame special strategy to minimize NO emission is needed because it is very sensitive to a small amount of $N_2$. Special attention is needed on CO emission by flame quenching, because of increased CO concentration. Spatial NO production rate of oxygen-enhanced combustion is different from that of air and oxygen-enhanced-EGR combustion in that thermal mechanism plays a role of destruction as well as production. In case CH$_4$/O$_2$-$CO_2$flame contains more than 40% $CO_2$it is possible to maintain the same EINO as that of CH$_4$/Air flame with accomplishing higher temperature than that of CH$_4$/Air flame. EINO decreases with increasing strain rate, and those effects are augmented in CH$_4$/O$_2$flame.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.185-190
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• 2001

Numerical Study with detailed chemistry has been conducted to investigate the flame structure and NOx formation characteristics in oxygen-enhanced$(CH_4/O_2-N_2)$ and oxygen-enhanced-EGR$(CH_4/O_2-CO_2)$ counter diffusion flame with various strain rates. A small amount of $N_2$ is included in oxygen-enhanced-EGR combustion, in order to consider the inevitable $N_2$ contamination by $O_2$ production process or air infiltration. The results are as follows : In $CH_4/O_2-CO_2$ flame it is very important to adopt a radiation effect precisely because the effect of radiation changes flame structure significantly. In $CH_4/O_2-N_2$ flame special strategy to minimize NO emission is needed because it is very sensitive to a small amount of $N_2$. Special attention is needed on CO emission by flame quenching, because of increased CO concentration. Spatial NO production rate of oxygen-enhanced combustion is different from that of air and oxygen-enhanced-EGR combustion in that thermal mechanism plays a role of destruction as well as production. In case $CH_4/O_2-CO_2$ flame contains more than 40% $CO_2$ it is possible to maintain the same EINO as that of $CH_4/Air$ flame with accomplishing higher temperature than that of $CH_4/Air$ flame. EINO decreases with increasing strain rate, and those effects are augmented in $CH_4/O_2$ flame. Complementary study is needed with extending the range of strain rate variation.