• 대한치과보철학회지
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• 제17권1호
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• pp.35-46
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• 1979

A number of experimental studies have been carried out in order to clarify the question as to how temporomandibular joint adapt to the changes of mandibular movement and occlusal equilibration. Recently, the studies on the interrelations between anatomical structure of temporomandibular joint and the state of occlusion have been actively performed in dentistry particularly in prosthodontic field. Author performed extraction of unilateral mandibular molars in 30 mature male rats, and observed histological changes of temporomandibular joint through the light microscope. Following results were obtained. 1. The loss of unilateral teeth gave rise to the changes in the location of condylar head, that is, interior displacement of condylar head in the extraction side and upper displacement in the non-extraction side. 2. Articular disk was compressed by the interior surface of condylar head, resulting in its extension below the condylar neck in the extraction side, and the histological arrangement of the compressed area showed irregular feature. 3. The extension of articular disk below the condylar neck was accompanied with the contraction of muscle fibers which were originated from the articular disk. 4. The cartilage layer of articular fossa to the exterior of the extraction side showed hypertropy. 5. Early in the experiment, the inernal extremity of condylar head of extract ion side showed bone resorption, and cartilage layer of condylar head showed hypertropy. At 12 weeks after experiment, the condylar surface showed flattened, and the cartilage layer of condylar head was replaced by the compact bone. 6. The articular disk showed the formation of pannus in the extraction side as well as in the non-extraction side. 7. The occlusal disturbance due to unilateral missing teeth has brought about the non-inflammatory retrogressive change and osteoarthrotic change late in the experiment.

• 한국해양공학회지
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• 제31권6호
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• pp.419-424
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• 2017

Unlike other leisure boats, a sailing yacht is propelled by wind power using sails that are controlled by the crew. Therefore, the ergonomic design of the equipment that the crew has to operate for sailing might be very important. However, it is difficult to find design rules and regulations for the equipment arrangement of a sailing yacht based on ergonomics. In this study, the arrangement design for the height and side plate angle of a winch for a sailing yacht was examined from an ergonomic design point of view. In a simulation, a Korean male in his 20s was selected as a human model for a grinder. The physical load was analyzed when he was operating a winch using a 3D human simulation. The lower back load showed the highest value when using the grinder at $90^{\circ}$ and $180^{\circ}$. Based on the results for the lower back load when using the grinder with various winch heights, it is suggested that the winch height from the cockpit floor to the top of the winch should be more than 40% of the height of the human operator. In addition, according to the results for the lower back load with various horizontal distances from the body, it is suggested that the side plate angle should be less than $16^{\circ}$.

• 대한치과보철학회지
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• 제15권1호
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• pp.34-42
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• 1977

The author attempted to observed the histological changes of the temporomandibular joints of rabbits by including malocclusion. Thirth-two healthy male rabbits were devided into two groups; control and experimental group. Eight rabbits were kept as control group, while metal crowns were seated on unilateral lower molar teeth of twenty-four rabbits as experimental group. And the interocclusal distance of the incisal edge was kept 1.5mm from the begining to the end of the experimental periods. Rabbits of each group, one of control group and three of the experimental gorup, were killed at the intervals of one day, three days, one week, two weeks, four weeks, six weeks, eight weeks, and twelve weeks after experiment. The temporomandibular joint including condyle head, articular disc and glenoid fossa were excised and decalcified. The decalcified sections were made histologic sections. The results obtained were as follows. 1. The regressive changes of the condylar head were the main reaction in this experiment that consist of decreasing or increasing thickness of the fibrocartilage zone with hyaline degeneration, decreasing of the cellularity of the proliferative zone, and the irregularity of the arrangement of chondrocytes and size of the lacunae of cartilage cells with chondroclasia and osteoclasia in hypertrophic zone. 2. The regressive changes of the condylar surface of the crown seated side were persisted to the end of the experiment. 3. On the non-crown seated side, severe aggressive changes occurred in initial stage, but hyperplastic changes of the condylar surface noted in the middle of the experimental periods. 4. Although aggressive changes occurred in initial stage of experiment on the non-crown seated side, hyperplastic changes of the condylar surface were noted in the middle of the experimental periods, and remodeling appeared at the termination of the experimental periods. 5. The articular disc exhibited pannus formation on both crown seated and non crown seated side from the beginning of the experiment. The pannus persisted throughout the experiment on the crown seated side, but on the non-crown seated side it disappeared from six week group.

• Membrane and Water Treatment
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• 제7권4호
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• pp.297-311
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• 2016

Modeling and simulation of air humidification by hollow fiber membrane contactors are investigated in the current study. A computational fluid dynamic model was developed by solving the k-epsilon turbulence 2D Navier-Stokes equations as well as mass conservation equations for steady-state conditions in membrane contactors. Finite element method is used for the study of the air humidification under different operating conditions, with a focus on the humidity density, total mass transfer flux and velocity field. There has been good agreement between simulation results and experimental data obtained from literature. It is found that the enhancement of air stream decreases the outlet humidity from 0.392 to 0.340 (module 1) and from 0.467 to 0.337 (module 2). The results also indicated that there has been an increase in air velocity in the narrow space of shell side compared with air velocity wide space of shell side. Also, irregular arrangement has lower dead zones than regular arrangement which leads to higher water flux.

• 건축역사연구
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• 제25권1호
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• pp.7-21
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• 2016

The purpose of this paper is to study on the characteristic of site planning of Hadrian's villa. The whole site planning of Hadrian's villa can be divided by different characteristic four groups(I-IV). It is analysed to the whole site plan of such huge complex and the site planning of partial each group which is organically connected each other. The results of this study are as follows: 1. Hadrian's villa was arranged in adapt to natural condition according to a gentle inclination by topography and terrain of the whole site which many different buildings are oriented towards natural landscape of the site and the site surroundings. 2. The site planning of Hadrian's villa is composed of dividing into four groups as plan segmentalized through various land use plan, considering for territory of functional aspect and direction of axis formed by situation and direction of topography and terrain. 3. The concept of site planning to buildings of Hadrian's villa is composed through each other connection; the first, meeting, crossing and merging with each other from arrangement by several axises, the second, change of direction with as the center a part of corner of buildings and the third, facing or inserting system to side and side, side and a part of corner of building.

• 대한기계학회논문집B
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• 제31권6호
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• pp.566-573
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• 2007

Flows around two oscillating cylinders in side-by-side arrangement at Re=185 are simulated using an immersed boundary method. The cylinders oscillate vertically in opposite directions in uniform cross-flow. We describe flow patterns, drag and lift forces by varying distance between two cylinders $(1.4{\leq}g{\leq}2.2,\;1.0{\leq}g{\leq}1.8)$ and oscillating frequency ratios $(f_e/f_o=0.8,\;f_e/f_o=1.0\;and\;f_e/f_o =1.2)$. Wake patterns, drag and lift coefficients are affected by both of frequency ratio and gap between two cylinders. Near wakes of each case are classified with the definition of previous studies.

• 설비공학논문집
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• 제18권9호
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• pp.729-737
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• 2006

Air-side forced convective heat transfer of a plate fin-tube heat exchanger is investigated by experimental measurement and numerical computation. The heat exchanger consists of staggered arrangement of refrigerant pipes of 10.2 m diameter and the pitch of fins is 3.5 m. In the experimental study, the forced convective heat transfer is measured at Reynolds number of 1082, 1397, 1486, 1591 and 1649 based on diameter of refrigerant piping and mean velocity. Average Nusselt number for the convective heat transfer coefficient is also computed for the same Reynolds number by commercial software of STAR-CD with standard $k-{\varepsilon}$ turbulent model. It is found that the relative errors of average Nusselt numbers between experimental and numerical data are less than 6 percentage in Reynolds number of $1082{\sim}1649$. The errors between experiment and other correlations are ranged from 7% to 32.4%. But the correlation of Kim at al is closest to the experimental data within 7% of the relative error.

• 한국광학회지
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• 제33권1호
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• pp.11-21
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• 2022

본 연구에서는 자율주행차의 라이다 센서용 광위상배열(optical phased array, OPA)에서 우수한 신호 품질을 얻을 수 있는 방법에 대해 조사하였다. OPA를 구성하는 광 안테나가 주기적으로 배치되어 있는 경우에는 grating lobe의 형성으로 인해 빔 조향의 범위가 제한된다. 광 안테나가 비주기적으로 배치된 OPA에서는 한 개의 main lobe만 형성되어 넓은 조향 범위가 가능하지만 side lobe에 의한 잡음의 영향으로 신호 품질이 저하된다. 본 논문에서는 이러한 비주기적인 OPA에서 발생하는 잡음을 최소화하고 신호 품질을 향상시키기 위한 최적화 연구를 수행한 결과를 보고한다. 최적화를 위한 목적 함수로는 side-lobe level (SLL)을 이용하였고, SLL이 가장 낮은 안테나 배열을 구하기 위한 최적화 기법으로는 입자 군집 최적화(particle-swarm optimization, PSO), 유전 알고리즘(genetic algorithm, GA), 패턴 검색 알고리즘(pattern-search algorithm, PSA) 등을 적용하였다. 128 채널의 광 안테나 배치로 이루어진 비주기적 OPA에서 위 3가지 최적화 기법을 적용하여 결과를 비교하였다. 전반적으로 PSO와 GA는 서로 유사한 최적화 결과를 보였고, PSA는 이와는 약간 차별적인 특성을 보였다. 최적화가 이루어진 각도가 45도보다 작을 때에는 최적화 각도가 작을수록 모든 조향 각도에서의 평균적인 SLL 값이 증가하는 경향을 보였지만, 최적화가 이루어진 각도가 45도 이상일 경우에는 최적화 알고리즘에 관계없이 -13 dB 이하의 평균 SLL 값을 얻을 수 있었다. 본 연구를 통해 비주기적인 OPA에서 고품질의 신호를 얻기 위한 최적의 안테나 배열을 구하는 데 있어서 PSO, GA, PSA의 최적화 알고리즘이 유용하게 활용될 수 있음을 보였다.

• 건축역사연구
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• 제29권6호
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• pp.29-40
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• 2020

This research is conducted focusing on the 7-Dories type wooden buildings showing different rafter installation. This research found the reason why the rafter configuration look different each other and the relationship the between rafters and the Dory. Factors were compared to determine why the rafter configuration show the formal differentiation. The comparison factors are as follows: 1. The type of rafter installation is related to the longitudinal length of the building. 2. The type of rafter installation is related to the number of Kans on the side of the building and is proportionate. 3. The type of rafter configuration is related to the Dory arrangement and is proportionate. 4. The type of rafter configuration is related to the Dory's vertical arrangement. If the Dory arrangement is small, it is identified as two-stage rafter configuration. And if the Dory arrangement is large, it is identified as three-stage rafter configuration. Eventually, it was confirmed that the rafter configuration were affected by the Dory arrangement.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1996년도 춘계 학술대회논문집
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• pp.105-110
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• 1996

In the present paper, flow fields around two dimensional single and two circular cylinders are analysed by a finite difference method. Navier-Stokes and the continuity equations an solved to simulate the flow fields. A overlapped grid system(the composite of a body boundary-fitted grid system near the body and a rectangular grid system for other flow fields) is used for this calculation. In the use of overlapped grid system, it is most significant thing to exchange the physical quantities from one grid system to the other one continuously, In this research, the linear interpolations of physical quantaties are done for this purpose in the overlapped region. The numerical calculations are carried out for the flows around a circular cylinder and two cylinders to verify the accuracy of present method. The flow fields around two cylinders facing the flow with side by side and tandem arrangement are analysed. The results are compared to other experimental and computational ones done in other single grid system.