• 대한기계학회논문집
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• 제18권12호
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• pp.3276-3286
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• 1994

In most direct contact liquid-liquid heat exchangers, oil or hydrocarbon with a density less than water is normally used as dispersed working fluid. The main difficulty that arises with this arrangement lies in the control of the interface at the top of the column. When it is connected with a solar collector which uses water as its working fluid, the main difficulties arise from the fact that the water can be frozen during winter time. In order to solve these problems and to demonstrate the technical feasibility of a direct contact liquid-liquid heat exchanger, liquids heavier than water with low freezing temperature has been utilized as dispersed phase liquids in a small laboratory scale model made of pyrex glass. In the present investigation, dimethyl phthalate(C/sub 6/H/sub 4/)COOCH/sub 3/)/sub 2/) and diethyl phthalate (C/sub 6/H/sub 4/(CO/sub 2/C/sub 2/H/sub 5/)/sub 2/) are utilized as heavy dispersed phase working fluids. The results of the present investigation the technical in the utilization of heavier dispersed working liquid in the spray-column liquid-liquid heat exchanger for a solar system. The overall average temperature difference along the column is found to be almost half of the initial temperature difference between the dispersed and the continuous phase. Despite the fact that the two phthalates tested in the experiment differ significantly in some of their physical properties, the volumetric heat transfer coefficients in terms of dispersed fluid superficial velocities were found to be similar for both phthalates tested.

• Korean Chemical Engineering Research
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• 제51권2호
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• pp.245-249
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• 2013

천연가스액 회수공정 중 프로판, 부탄, 이소 부탄의 분별증류 과정의 에너지 효율을 향상시키는 방안으로 일반 분리벽형 증류탑 이중배열(DDWC), 일반 분리벽형 증류탑(DWC)과 탑저 분리벽형 증류탑(BDWC)의 순차배열 및 일반 분리벽형 증류탑에 탑정증기 재압축 히트펌프가 탑저 분리벽형 증류탑에 조합된 복합배열을 제안하고 그 성능을 분석하였다. 그 결과 이러한 배열들이 일반 증류배열과 비교하여 재비기와 응축기에서의 에너지 소모를 상당량 줄여주는 효과를 가지는 것을 확인하였으며 소요되는 증류탑의 수와 직경이 줄어들게 되어 투자비용이 대폭 절감될 수 있음을 알 수 있었다. 또한 탑저 분리벽형 증류탑에 탑정증기 재압축 히트펌프를 조합하는 내부 및 외부 열통합 조합을 통하여 가장 많은 운전비용 절감을 달성할 수 있음을 확인하였다.

• Korean Chemical Engineering Research
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• 제50권3호
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• pp.505-510
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• 2012

기포탑 반응기에서의 기체 체류량은 기포의 크기 분포 및 상승 속도와 밀접한 연관성을 갖는다. 따라서 많은 연구자들에 의하여 기포탑 반응기 내에 기포의 크기를 제어하기 위한 연구들이 진행되어 왔다. 본 연구에서는 스파져 이외의 영역에서도 기포의 거동을 제어하고 기체 체류량을 증진시키기 위하여 다단형 기포탑 반응기를 사용하였다. 특히, 3 종류의 서로 다른 크기의 반응기를 사용하여 다단 다공판이 기포의 유동 특성에 미치는 효과를 확인하였다. 나아가 개별 기포가 다공판을 통과하였을 때의 쪼개짐 빈도수 및 크기 분포 변화에 대하여 관찰함으로써 다공판의 영향에 대한 이해를 넓혔다. 또한 다양한 다공판 배치 형태에 따른 유동 특성을 관찰함으로써 다단형 기포탑 반응기에서의 다공판 설치에 대한 기준을 제시할 수 있었으며, 이를 바탕으로 높이 22 m, 직경 0.36 m의 벤치 스케일 다단형 기포탑 반응기를 제작하여 그 성능을 확인하였다.

• 한국농촌건축학회논문집
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• 제12권3호
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• pp.19-26
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• 2010

This study is aimed to look into the craftsmanship non-educated constructors in Korean-style secondary stations(Gong-So) of Naepo region which is located in the northwestern Chungcheongnam-do. Although the area was persecuted as one of three cradles of Korean Catholicism, Catholic activities flourished there. The 13 cases of Korean-style secondary stations were selected through a survey report list about modern cultural assets of Chungcheongnam-do published in december 2004. This study examined the methods of plan layout and framework of Gong-So to look into craftsmanship of non-educated constructors, the results are as follows; The methods of plan layout are divided into three types according to existence and arrangement of inner column(Nae-Ju); 'Layout with Nae-Ju' is considered as the primary form of Korean-style Gong-So with using regular Nae-Ju. 'Layout with the different position of the center between Nae-Ju and exterior column(Oe-Ju)' and 'layout without Nae-Ju' is appeared in Korean-style Gong-So which is important to assembly and alter function. The methods of framework are appeared variously according to different plan layout for securing worship space. The unusal beam(Chung-Ryang) is used to solve different spans of altar and narthex. When space was formed widely without Nae-Ju, diagonal members and M letter type rafters are used, they are influenced by the technique of western wooden roof truss.

• Steel and Composite Structures
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• 제4권4호
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• pp.303-315
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• 2004

Frame composed of concrete-filled steel tubular columns and I-shaped steel beam has been researched in order to development reasonable connection details. The present paper describes the results of an experimental program in four different connection details. The connection details considered include through-bolt between I-shaped steel beams and concrete-filled steel tubular columns and two details of welded connections. One of the welded connection details is stiffened by angles welded in the interior of the profile wall at the beam flange level. The specimens were tested in a cruciform loading arrangement with variable monotonic loading on the beams and constant compressive load on the column. For through-bolt details, the contribution of friction and bearing were investigated by embedding some of the bolts in the concrete. The results of the tests show that through-bolt connection details are very ductility and the bearing is not important to the behavior of these moment connections. The angles welded in the interior of the profile wall increase the strength and stiffness of the welded connection detail. In addition, the behavior curves of these connections are compared and some interesting conclusions are drawn. The results are summarized for the strength and stiffness of each connection.

• Coupled systems mechanics
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• 제3권4호
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• pp.367-384
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• 2014

The study deals with the physical modeling of a typical single storeyed building frame resting on pile foundation and embedded in cohesive soil mass using the finite element based software SAP-IV. Two groups of piles comprising two and three piles, with series and parallel arrangement thereof, are considered. The slab provided at top and bottom of the frame along with the pile cap is idealized as four noded and two dimensional thin shell elements. The beams and columns of the frame, and piles are modeled using two noded one dimensional beam-column element. The soil is modeled using closely spaced discrete linear springs. A parametric study is carried out to investigate the effect of various parameters of the pile foundation, such as spacing in a group and number of piles in a group, on the response of superstructure. The response considered includes the displacement at the top of the frame and bending moment in columns. The soil-structure interaction effect is found to increase the displacement in the range of 38 -133% and to increase the absolute maximum positive and negative moments in the column in the range of 2-12% and 2-11%. The effect of the soil- structure interaction is observed to be significant for the type of foundation and soil considered in this study. The results obtained are compared further with those of Chore et al. (2010), wherein different idealizations were used for modeling the superstructure frame and sub-structure elements (foundation). While fair agreement is observed in the results in either study, the trend of the results obtained in both studies is also same.

• 한국산학기술학회논문지
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• 제14권2호
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• pp.927-935
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• 2013

최근 지진의 발생빈도가 과거에 비해서 증가하면서 교량 구조물에도 내진성능에 대한 연구가 활발하게 진행되고 있다. 그 중 교량 하부 구조물의 경우에는 횡방향 하중에 저항하기 위하여 소성힌지 부분에 심부 구속 횡철근을 배근하여 횡방향 구속 효과를 증대시키고 있다. 이것은 심부 구속 횡철근 배근을 통하여 교각에 필요한 강성 및 연성을 확보하여 내진성능을 향상시키고자 하는 것이다. 현재 심부구속 횡방향 철근량 산정에 대한 설계 기준은 국내의 도로교 설계 기준과 국외의 대다수 설계 기준이 동일한 설계 기준을 사용하고 있고, 이는 중실 철근 콘크리트 기둥을 대상으로 제안되어 있다. 이 식을 내부 구속 중공 RC 기둥에 그대로 적용하기에는 그 구성 요소가 상이하고 거동 특성이 다르기 때문에 무리가 따른다. 본 연구에서는 내부 구속 중공 RC 기둥에 현행 기준을 적용하였을 때의 해석적 방법에 의한 변위 연성도 분석을 통하여 특성을 분석하고 경제성 있고 합리적인 설계가 될 수 있도록 수정식을 제안하였다.

• Archives of Plastic Surgery
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• 제35권5호
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• pp.574-580
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• 2008

Purpose: Philtral deformity is a stigma of secondary cleft lip nose. It occurs from the false arrangement of orbicularis oris muscle and the scar of previous operation. Various methods have been used to correct this deformity. We successfully corrected philtral deformity using overlapping of orbicularis oris muscle flap. Methods: From November 2000 to August 2007, we performed 39 cases of correction of philtral deformity in secondary cleft lip nose with overlapping of orbicularis oris muscle flap. Their age ranged from 5 to 53 years old. Existing scar tissue of previous operation was deepithelialized and preserved as scar flap. Lateral orbicularis oris muscle flap was elevated, advanced and overlapped upon medial muscle flap after dissection of orbicularis oris muscle of both sides. Reconstruction of philtral column was made from overlapping area by fixation of end part of lateral muscle flap to the point between philtral dimple and column. The degree of muscle flap advancement was decided by correction state of lateral muscle bulging. Correction of nostril floor depression or whistle deformity was also performed with preserved scar flap, if necessary. Results: Realignments of orbicularis oris muscle were possible in the majority of the patients and final results of philtral reconstruction were satisfactory mostly. Correction of nostril floor depression and whistle deformity was also achieved. Additional correction was performed later to 4 patients in whom insufficient reconstruction was noted. No significant complication was observed. Conclusion: More natural and symmetric philtrum was acquired with overlapping of orbicularis oris muscle flap. To the authors' knowledge, it is an easy and effective method for correction of philtral deformity through anatomical rearrangement of distorted orbicularis oris muscle with relatively simple procedure.

• Steel and Composite Structures
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• 제25권1호
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• pp.117-126
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• 2017

The component method is an analytical approach for investigating the moment-rotation relationship of steel connections. In this study, the component method was improved from two aspects: (i) load analysis of mechanical model; and (ii) combination of spring elements. An optimized component method with more reasonable component models, spring arrangement position, and boundary conditions was developed using finite element analysis. An experimental testing program in two major-axis and two minor-axis connections under symmetrically loading was carried out to verify this method. The initial rotational stiffness obtained from the optimized component method was consistent with the experimental results. It can be concluded that (i) The coupling stiffness between column and beam flanges significantly affects the effective height of the tensile-column web. (ii) The mechanical properties of the bending components were obtained using an equivalent t-stub model considering the bending capacity of bolts. (iii) Using the optimized mechanical components, the initial rotational stiffness was accurately calculated using the spring system. (iv) The characteristics of moment-rotation relationship for beam to column connections were effectively expressed by the SPRING element analysis model using ABAQUS. The calculations are simpler, and the results are accurate.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.213-216
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• 2008

슬래브에 폴리스티렌을 이용한 경량폼을 적용할 경우, 슬래브 중량이 감소함에 따라 보다 경간이 증가하거나 슬래브 지지 부재 크기가 감소될 수 있다. 하지만 플랫플레이트 구조에서 경량폼을 사용한 슬래브는 기둥주위 위험단면에서의 뚫림전단성능이 저하될 수 있다. 그러나 이에 관한 내력산정을 위한 기준이 없으며, 기존 연구 또한 부족한 실정이다. 본 논문은 폴리스티렌 경량폼을 사용한 슬래브-기둥 접합부의 뚫림전단내력을 파악하기 위하여 실시한 뚫림전단 실험에 관한 것이다. 주요 변수는 기둥의 크기, 폴리스틸렌 폼의 배치형태, 전단보강 유무 등으로 총 4개 실험체를 계획하였다. 실험을 통하여 균열 및 파괴모드, 하중-변위곡선, 뚫림전단강도 등을 분석함으로써 경량폼을 사용한 슬래브의 뚫림전단 성능을 파악하였다.