• Polymer(Korea)
• /
• v.30 no.5
• /
• pp.373-379
• /
• 2006

Polymerizable discotic liquid crystals containing diacetylene and acryloyl groups were formed through hydrogen bonding between phloroglucinol core and polymerizable pyridine derivatives, and their photopolymerization behavior was investigated. The discotic complexes exhibited discotic columnar and rectangular columnar mesophases depending on the number of aromatic rings. Photopolymerization of the discotic complexes was carried out by UV irradiation in the liquid crystalline state. IR and UV-Vis spectroscopy affirmed that diacetylene and acryloyl groups were selectively Polymerized, and that crosslinked polymers containing short conjugated diacetylene oligomers were produced by 1,4-addition. X-ray diffraction experiment showed that the columnar order in the discotic complex containing phenyl-pyridine moiety was maintained after photopolymerization, and that the rectangular columnar order in he discotic Complex with biphenyl units was changed to the lamellar order.

• Solar Energy
• /
• v.18 no.3
• /
• pp.217-228
• /
• 1998

The purpose of this research is to investigate the characteristics of static and total pressure distribution in the upward free water jet system impinged on a downward flat plate. The rectangular nozzle was used and its contraction and aspect ratio was five and about seven respectively. Experimental conditions considered were jet velocity, distance between nozzle and flat plate, height of supplementary water. It was founded that pressure distribution on the flat plate had the Gaussian curve when the pressure at stagnation point and impinging half width were chosen as the scaling parameters. The maximum pressure was shown at the stagnation point. The central impingement velocity decreased with the increment of distance between nozzle and flat plate, and its slop of decay was similar to that of chracteristics decay region in the three-dimensional free jet.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.53-56
• /
• 2008

In this investigation, results of laboratory tests on six reinforce concrete flat plate interior connections with elongated rectangular column support which has been used widely in tall residential buildings are presented. The purpose of this study is to evaluate an effect of column aspect ratio(${\beta}$c=$c_1/c_2$) on the hysteretic behavior under earthquake type loading. The aspect ratio of column section was taken as 0.33${\sim}$3($c_1/c_2$=1/3, 1/1, 3/1). Other design parameters such as flexural reinforcement ratio of slab and concrete strength was kept constant as ${\rho}$=1.0%, 1.5% and $f){ck}$=40MPa, respectively. Gravity shear load($V_g$) was applied by 30 percents of nominal vertical shear strength(0.3$V_o$) of the specimen. Experimental observations on punching failure pattern, peak lateral-load and story drift ratio at punching failure, and stiffness degradation were achieved and discussed in accordance with different column aspect ratio.

• Journal of the Korean Institute of Rural Architecture
• /
• v.5 no.1
• /
• pp.42-61
• /
• 2003

The purpose of this study was to analyze the characteristics of wooden anglican church architecture in Chungcheong area. For this study, I have selected ten anglican churches, and have studied the characteristic through the actual survey and analysis. This study focuses on the architectural characteristics and evolution of wooden anglican church in chungcheong area, based on the actual survey and historical analysis. The results of this study is as follows:1)The shape of plan is long axis composed of the entry and altar. 2)The shape of elevation is composed of the roof form and existence and nonexistence of bell-tower. 3)The shape of section in divided into one kan and three kan way, by the existence and nonexistence of a row of columns in the interior. 4)The structure and design follows roof-framing.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.21 no.3
• /
• pp.145-152
• /
• 2017

The objective of this study is to propose a simple and accurate analytical model for HSS braces. For this purpose, a physical theory model is adopted. Rectangular hollow section steel (HSS) braces are considered in this study. To accurately simulate the cyclic behavior of braces using the physical theory model, empirical equations calculating constituent parameters are implemented on the analytical model, which were proposed in the companion paper. The constituent parameters are cyclic brace growth, cyclic buckling load, and the incidence of local buckling and fracture. The analytical model proposed in this study was verified by comparing actual and simulated cyclic curves of brace specimens. It is observed that the proposed model accurately simulates the cyclic behavior of the braces throughout whole response range.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2005.05b
• /
• pp.649-653
• /
• 2005

유역형상의 변화에 따라서 이동강우가 유출에 미치는 영향을 운동파이론을 적용하여 분석하였으며, 유역형상은 신장형유역과 정4각형유역 및 장방형유역에 대하여 분석하였고, 이동강우 분포형은 균등분포형, 전진형, 지연형, 중앙집중형을 사용하였다. 이와 같은 형상의 유역에 대하여 다양한 이동속도를 가진 강우가 유역내 하천의 상류방향, 하류방향, 횡방향으로 이동할 때 강우분포형에 따르는 유출수문곡선을 모의하여 그 특성을 비교분석하였다. 유출수문곡선의 모양과 첨두시간, 첨두유량은 시간적, 공간적으로 변화하는 강우와 유역형상에 의하여 크게 영향을 받는다. 횡방향의 이동강우에서는 상류방향과 하류방향의 경우보다 더 큰 첨두유량이 발생하며, 하류방향 이동강우의 첨두유량은 상류방향의 첨두유량보다 더 크게 나타났다. 신장형유역의 경우 하류방향 이동강우의 첨두시간은 상류방향과 횡방향의 경우보다 더 지체되며, 수문곡선의 총유출량과 기저시간은 강우속도가 증가함에 따라 감소하였다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2009.05a
• /
• pp.806-809
• /
• 2009

도시주변 하천에서 수공구조물의 설치가 하천흐름에 미치는 영향은 매우 크게 나타난다. 특히 최근 급격한 기온상승에 따른 게릴라성 호우에 의한 홍수시 그 영향은 더욱 크게 나타나 재산, 인명 피해가 증가하고 있는 추세이다. 본 연구에서는 도시주변 하천이며, 관측자료가 풍부한 금강유역의 금남교 지점으로부터 공주대교지점까지 약 14.7km 지점에 대하여 교각의 설치각도가 미치는 영향에 대하여 분석 하였다. 교각의 설치각도에 대한 분석을 위하여 장방형교각(폭${\times}$길이: $3{\times}8m$)으로 가정하여 RMA-2모형을 이용하였으며, 교각의 설치각도는 $0^{\circ}$, $15^{\circ}$, $30^{\circ}$, $45^{\circ}$로 표면유속 및 수위분포에 대한 모의를 하였다. 모의된 결과는 현재 설치되어있는 원형교각(지름: 3m의 병렬교각)의 경우와 교각이 없는 경우를 비교하였고, 유량측정에 의한 관측자료(2003년 6월 20일${\sim}$2004년 6월 20)와 모의자료를 비교하여 매개변수 보정을 실시하였다.

• 유체기계공업학회:학술대회논문집
• /
• 1998.12a
• /
• pp.70-77
• /
• 1998

The rise in pressure across the impeller blade of an axial flow fan depends on the angle of attack. At a low back pressure, the air volume will be large and the angle of attack is small. The gradual increase of the back pressure approached stall zone which is not stationary but travels blade to blade passage. In consequence, a region occurs around these blades with large vibration in the flow. To avoid these stall operation, the stall detector in the axial flow fans has been designed to detect stalling condition with a manometer or differential pressure switch by electric mechanism.

• Journal of Korea Multimedia Society
• /
• v.2 no.1
• /
• pp.80-88
• /
• 1999

In this paper, we propose a Special Memory for Graphics(SMGRA) which accelerates memory access time for graphics operations. The SMGRA has a rectangular array memory architecture which has already proposed by Whelan to process pixels in the rectangle area simultaneously, but the SMGRA should improve address decoding time and reduce the number of address pins by using address multiplexing scheme. The SMGRA has a Z-value comparator in the DRAM which is to convert read-modify-write Z buffer into single-write only operation that improves approximately 50% frame buffer access bandwidth.

• Proceedings of the KIEE Conference
• /
• 2008.04b
• /
• pp.19-21
• /
• 2008

현행 배전선로의 전주근가(1.2m 장방형)는 오거크레인을 이용한 건주공사 완료 후 전주근가 시공을 위한 별도의 인력 또는 백호우 장비가 추가로 투입피어 시공함으로써 인력으로는 공사시간이 장기간 소요되고 백호우장비로는 작업장 환경훼손과 시공원가 상승의 문제점이 있었다. 이러한 문제점을 해소하기 위하여 건주공사에 사용되는 오거크레인의 굴착 직경을 80cm까지 확장 가능한 '신축형 오거크레인용 유압식 확장기'와 원형 굴착공에 시공이 가능한 '아치형 전주근가'를 개발하고 이를 이용한 시공기술을 개발함으로써 동일장소에서 굴착작업이 수반되는 건주작업, 전주근가 매설작업을 가능하게 하여 장비활용성 증대, 작업장 환경개선, 공사기간 단축 및 시공원가 절감 등의 효과가 기대되는 기술을 개발하였다.