• Structural Engineering and Mechanics
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• 제20권4호
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• pp.451-463
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• 2005

Structural members commonly employed in marine and off-shore structures are usually fabricated from plates and shells. Collision of this class of structures is usually modeled as plate and shell structures subjected to dynamic impact loading. The understanding of the dynamic response and energy transmission of the structures subjected to low velocity impact is useful for the efficient design of this type of structures. The transmissions of transient energy flow and dynamic transient response of these structures under low velocity impact are presented in the paper. The structural intensity approach is adopted to study the elastic transient dynamic characteristics of the plate structures under low velocity impact. The nine-node degenerated shell elements are adopted to model both the target and impactor in the dynamic impact response analysis. The structural intensity streamline representation is introduced to interpret energy flow paths for transient dynamic response of the structures. Numerical results, including contact force and transient energy flow vectors as well as structural intensity stream lines, demonstrate the efficiency of the present approach and attenuating impact effects on this type of structures.

• 한국지반환경공학회 논문집
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• 제16권3호
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• pp.5-13
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• 2015

해일에 의한 바닷물의 월류는 방조제 구조물에 피해를 유발시킨다. 지금까지 발생된 마운드 형태 방조제의 파괴 유형 조사 결과, 육지 쪽 마루부 파손과 선단부의 세굴이 대표적인 파괴 사례로 지목되었다. 이와 같은 파괴를 유발하는 가장 큰 원인은 월류에 의해 발생된 압력과 유속이다. 본 연구에서는 에너지 관점에서 마운드 형태 방조제에서 압력과 유속을 산정할 수 있는 이론해를 제안하고 검증하였다. 이를 위해 방조제 마루부와 선단부에 흐름을 유사정적비회전류로 보고 동심원유선이 형성된다고 가정하였다. 한계흐름조건과 베르누이정리를 이용하여 방조제 마루부와 배면 선단부에서의 작용하는 압력 및 유속 산정식을 유도하였다. 이들 식을 이용하여 동심원유선 및 월류고를 가정하여 마루부와 선단부에서 압력과 유속을 산정하였다. 그 결과 마루부에서는 부의 압력이 선단부에서는 양의 압력이 각각 크게 작용하는 것으로 나타났으며 유속에 의한 전단응력도 작용하는 것을 확인하였다. 또한 제안된 이론해의 적용 한계에 대한 고찰도 이루어졌다.

• 한국시조학회지:시조학논총
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• 제24집
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• pp.223-258
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• 2006

본고는 음악상으로서의 시조 분류이다. 잣수에 의한 문학상 분류와는 달리 시조창은 선율에 따라 달라진다. 문학상으로는 단시조 중시조 장시조의 분류가 일반적이나 시조창은 평시조 지름시조 사설시조로의 분류가 일반적이다. 같은 시조창이면서 다른 명칭으로 불리워지고 있는 경우가 있고 다른 종류이면서 같은 명칭으로 불리워지고 있는 경우가 있어 시조창의 명칭에 대한 논의가 필요한 실정에 놓여있다. 몇몇 국악인들에 의해 시도는 되고 있으나 개념에 대한 구체적인 논증 없이 이루어지고 있어 이에 대한 체계적인 고구가 필요한 실정이다. 현재의 번다한 명칭들을 정리하고 시조의 분류 체계를 세우고자하는 데에 본고의 목적이 있다. 필자는 고악보와 현행 시조보, 기존 이론을 검토, 평시조 계열 지름시조 계열 사설시조 계열로 일단 3대별하고 여기에 현재 불리워지고 있는 시조창들이 어떤 계열에 속하는 것인가를 몇 가지 원칙에 의해 분류해보았다. 필자가 조사한 현행 시조 명칭 67가지를 필요한 16개의 명칭으로 줄여 분류했다. 이는 현재 불리워지고 있는 명칭들이 같은 시조이면서 표음이 다른 것도 있고 다른 시조이면서 같은 명칭으로 불리워지는 것들도 있다. 이의 복잡, 번다함을 피하기 위해 문학과 음악상의 개념을 고려, 일부 용어들을 정리했다. 1) 평시조 계열 : 평시조, 중허리 시조, 우조시조, 파연곡 2) 지름시조 계열 : 지름시조, 남창지름시조, 여창지름시조, 반지름시조, 온지름시조, 우조지름시조, 사설지름시조, 휘몰이 시조 3) 사설시조 계열 : 사설시조, 반사설시조, 각시조, 좀는 평시조 아직도 배자, 형태, 음계, 타장르와의 영향 관계 등 적지 않은 음악상의 작업들이 남아있고 그에 대한 이론 축척이 시급한 실정이다. 이러한 음악적인 부분들은 전문가, 국악인들의 면밀한 검토와 연구를 필요로 하고 있다 차후의 논문을 기대할 수밖에 없음을 밝혀둔다.

• 복식
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• 제28권
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• pp.65-84
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• 1996

The purpose of this study is to analyze the relation between the beauty of human body and the fashion illustration in each period And I attained my object through the investigation of features and changes of illustration which is given a vivid description of the features and development of ideal humam body beauty. By various methods I studied this subject. Frist I refered to sundry records Secondly I investiated the fashion illustrations which are included in Vogue. On the basis of this data I grasped the ideal types of human body beauty which is founded during the social change in each 10 years. And I analyzed the relation be-tween the ideal type and fashion illustration which show the change of fashion. The summary of result is as follows. 1. In the early part of the 20th century the beauty of human body is represented with the figure of large-sized beauty which emphasize shoulder and bust. And fashion ikllustration show 9 life-size broad shoulder full bust lim waist and hourglass silhouette. 2, In the 1910s the swell of strength vanishes gradually and shoulder and sleeve are straight type. And fashion illustration show 7 life-size high waist line. And that is tublar sil-houette of high waist and streamline shape in which bust and hip are not emphasized. 3. In the 1920s the ideal type of human body beauty is straight type which shows flat bust and unexaggerate hip. And fashion illus-tration is about 8 life-size tublar silhouette of low waist and lunger and slimmer and young style in which bust and hip are not emph-asized. 4. In the 1930s the ideal is womamly slim and long style. Fashion illustration is about 8 life-size and slim & long silhouette in which waist line is emphasized and bust and hip line come out. 5. In the 1940s the ideal type is womamly style which has narrow shoulder rich bast and slim waist. And fashion illustration is about 7 life-size and hourglass silhouette which has unartificial shoulder slim waist and empha-sized bust. 6. In the 1950s the ideal type is that of ro-bust health which emphasize build and muscu-lar system. And fashion illustration is 8.5 life-size and show full bust and made waist slimmer. That is sheath silhouette. 7. In the child who has full face with large eyeball slender and long leg: narrow and immatured body comparatively big head. And fashion illus-tration is 7 life-size and show slim and long neck flat bust long and slim limbs and big head. That is H type silhouette. 8. In the 1970s the ideal type is high stat-ure flat breast small hip and wide shoulders. And fashion illustration is wide shoulders and slim waist as 11 life-size and straight sil-houete. 9. In the 1980s the ideal type is extremely emphasized breadth of shoulder because healthy body and muscle are recognized as the symbol of ideal attractiveness. And fashion il-lustration is about 8.5 life-size and show mus-cular slim type that is slim silhouette. 10 At the present time the ideal type is slim and tall type which is empasized healthy beauty. And fashion illustration is 12 life-size which has healthy body and skin So that is slim and long type.

• Journal of Advanced Marine Engineering and Technology
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• 제38권10호
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• pp.1244-1250
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• 2014

The temperature of the main engine cabin of commercial vessel is very high. The material SS-316L undergoes creep damage at temperatures exceeding $450^{\circ}C$. It is essential to maintain the highly stressed engine cabin below the creep regime. Hence, seawater is employed in this kind of maritime vehicles as cooling liquid. It obtains the thermal energy at the cooling pipe line after passing through main engine cooling system. To harness the energy in the seawater, a turbine can be installed to absorb the energy in the seawater before being released into the sea. In this study, a cooling pipe line is selected to apply the tubular type hydro turbine for transferring the energy. Numerical analysis for investigating the performance and the internal flow characteristics of the tubular turbine is conducted. The results show that the maximum efficiency of 85.8% is achieved although the efficiency drops rapidly at partial flow rate condition. The efficiency descends slowly at the condition of excess flow rate. There is a relatively wide operating range of flow rate of this turbine to keep high efficiency at the excess flow rate condition. For the internal flow of the turbine, there is uniform streamline on the suction and pressure sides of the blade at the design point. However, the secondary flow appears at the suction and pressure sidesat the excess flow rate.In addition, it appears only at pressure side at the partial flow rate condition.

• 대한기계학회논문집B
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• 제22권1호
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• pp.12-24
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• 1998

The paper presents the mechanism of secondary flows and the associated total pressure losses occurring in turbine cascades with turning angle of about 127 and 77 degree. Velocity and pressure measurements are taken in seven traverse planes through the cascade passage using a prism type five hole probe. Oil-film flow visualization is also conducted on blade and endwall surfaces. The characteristics of the limiting streamlines show that the three dimensional separation is an important flow feature of endwall and blade surfaces. The larger turning results in much stronger contribution of the secondary flows to the loss developing mechanism. A large part of the endwall loss region at downstream pressure side is found to be very thin when compared to that of the cascade inlet and suction side endwall. Evolution of overall loss starts quite early within the cascade and the rate of the loss growth is much larger in the blade of large turning angle than in the blade of small turning angle.

• Korea-Australia Rheology Journal
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• 제16권3호
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• pp.117-128
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• 2004

The effect of molecular parameters on the steady vortex behaviors in the inertial viscoelastic flow past a cylinder has been investigated. FENE-CR model was considered as a constitutive equation. A recently developed iterative solution method (Kim et al., (in press)) was found to be successfully applicable to the computation of inertial viscoelastic flows. The high-resolution computations were carried out to understand the detailed flow behaviors based on the efficient iterative solution method armed with ILU(0) type pre-conditioner and BiCGSTAB method. The discrete elastic viscous split stress-G/streamline upwind Petrov Galerkin (DEVSS-G/SUPG) formulation was adopted as a stabilization method. The vortex size decreased as elasticity increases. However, the vortex enhancement was also observed in the case of large extensibility, which means that the vortex behavior is strongly dependent upon the material parameters. The longitudinal gradient of normal stress was found to retard the formation of vortex, whereas the extensional viscosity played a role in the vortex enhancement. The present results are expected to be helpful for understanding the inertial vortex dynamics of viscoelastic fluids in the flow past a confined cylinder.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 추계학술발표회
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• pp.27-30
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• 2001

Flow and transport at fracture intersections, and their effects on network scale transport, are investigated in three-dimensional random fracture networks. Fracture intersection mixing rules complete mixing and streamline routing are defined in terms of fluxes normal to the intersection line between two fractures. By analyzing flow statistics and particle transfer probabilities distributed along fracture intersections, it is shown that for various network structures with power law size distributions of fractures, the choice of intersection mixing rule makes comparatively little difference in the overall simulated solute migration patterns. The occurrence and effects of local flows around an intersection (local flow cells) are emphasized. Transport simulations at fracture intersections indicate that local flow circulations can arise from variability within the hydraulic head distribution along intersections, and from the internal no flow condition along fracture boundaries. These local flow cells act as an effective mechanism to enhance the nondiffusive breakthrough tailing often observed in discrete fracture networks. It is shown that such non-Fickian (anomalous) solute transport can be accounted for by considering only advective transport, in the framework of a continuous time random walk model. To clarify the effect of forest environmental changes (forest type difference and clearcut) on water storage capacity in soil and stream flow, watershed had been investigated.

• 항공우주기술
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• 제3권2호
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• pp.197-207
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• 2004

현재 개발중인 스마트 무인기는 일반적인 헬리콥터와 같이 수직이착륙이 가능할 뿐만 아니라 고정익기와 같이 고속의 비행이 가능함을 목표로 하고 있다. 그러므로 흡기구는 여러 비행조건에서 엔진이 제 효율을 낼 수 있도록 충분한 공기를 흡입하루 수 있어야 함은 물론이고 비행체의 운행속도에 따라서도 그 효율이 어느 이상 저하되지 않도록 설계되어야 한다. 본 논문에서는 고속 비행체에 적합한 pitot 형태와 엔진 특성에 따른 플레넘 챔버를 장착한 흡기구를 설계하였다. 그리고 CFD-ACE를 이용하여 설계된 흡기구의 성능 해석을 수행하였으며 엔진 내부에서의 swirl과 distortion을 조사하고 압력손실에 대해서 연구하였다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 추계 학술대회논문집
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• pp.95-99
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• 2004

The developing Smart UAV in KARI supposes high speed flight as like a conventional plane, as well as vertical takeoff and landing as like a helicopter. Therefore, the air intake system should be designed to provide the sufficient air flow to the engine and the maximum possible total pressure recovery at the engine intake screen over a wide range of flight conditions. For this purpose, we designed the intake system using a pilot type intake model and plenum chamber In this paper, we designed the intake model and analyzed the performance of designed intake system using the general-purpose commercial CFD code, CFD-ACE+ For 3-D calculation, we generated mesh using the unstructured gird and used $\kappa-\epsilon$ turbulence model. The analysis results of the total pressure variation and the velocity distribution was illustrated in this paper. The pressure recovery and distortion coefficient at a plane coincident with the compressor inlet were calculated and streamline variation through the intake system was investigated at the worst condition as well as the standard flight condition.