• 한국해양학회지:바다
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• 제3권4호
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• pp.228-233
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• 1998

본 연구는 비측량용 사진기를 이용한 근거리 사진측정법을 적용하여 해빈단면을 추정하는 방법을 제시한다. 수평면 위에 고정된 비디오로부터 획득한 경사비디오영상을 해석하는 방법을 기초로 다음 두 가지 관점을 고려하여 경사사진 해석에 적합한 방정식을 유도하였다. (1) 사진기가 광축에 대하여 회전되는 것을 허용하였다. (2) 정확도를 향상시키기 위하여 렌즈왜곡을 비롯한 사진 계통상의 오차를 보정하는 단순한 오차모형을 도입하였다. 수정된 방정식을 검증하기 위하여 1998년 2월에 동해시 해빈에서 사진촬영과 정밀한 수준측량을 수행하였다. 그 결과 근거리 사진측정을 통한 해빈단면 추정값과 실제 측량값 사이의 수직거리에 대한 RMS 오차는 10 cm 이내였다.

• 한국정밀공학회지
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• 제29권6호
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• pp.693-701
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• 2012

In this study, a small wind turbine airfoil specialized for national wind condition was designed in order to develop the furling control type HAWT. And then a flow analysis was carried out based on the blade drawing which was designed to characterize of the developed airfoil. The result of the flow analysis showed that the torque on the 3 blades was 180.23N.m. This is equivalent to an output power of 5.66kw and an output efficiency of 0.44. Then we produced and constructed a 3kW - furling control type HAWT by getting the system unit design technology such as the specialized furling control device. By operating this turbine, we could get 3kW of the rated power at a wind speed of 10.5m/s through the ability test. Cut-in wind speed was 2m/s, generator efficiency was 92% at the rated power output. Sound power level was 87.2dB(A). Also we observed that the output power was limited to 10.5m/s with furling system operation.

• 한국도로학회논문집
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• 제10권4호
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• pp.247-255
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• 2008

현행 도로설계의 기준이 되는 "도로의 구조 시설 기준에 관한 규칙 해설 및 지침"에서는 설계속도에 따라 도로 선형별 최소 설계기준을 정하고 있으며, 이 기준을 만족시키면 교통안전성 이 확보되는 것으로 규정하고 있다. 이러한 설계기준에 적용되고 있는 개별 설계요소들은 원칙적으로 차량 및 운전자 특성을 감안하여 설치기준이 정립되었으나, 설계요소간의 연관성 또는 일관성에 대한 깊이 있는 연구를 통해 제반 기준이 정립된 것은 아니다. 결과적으로, 현재의 도로설계기준이 개별 설계 요소들의 조합에 의해 결정되는 도로의 안전성, 일관성 문제를 모두 고려하지는 못하였다. 따라서, 본 연구에서는 기존의 설계기준에 내재된 문제점을 인지하고 해결을 위해 우선적으로 3차원 가속도를 고려한 선형 설계방안에 대한 연구를 수행하였으며, 이를 통해 더욱 안전하고 조화로운 도로건설을 유도하고자 한다.

• 한국금형공학회:학술대회논문집
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• 한국금형공학회 2008년도 하계 학술대회
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• pp.23-26
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• 2008

In order to examine the deformation characteristics of Al circular pipe underthe biaxial compression, the horizontal biaxial compression die for the experiment was manufactured. From this, in the various compressive strain rate (1 mm/min. ${\sim}$ 400 mm/min.)conditions, the circular pipes, which were made by Al materials, were investigated based on the properties change of cross section area, punch load and deformation behavior. The tensile and compressive strains were evaluated from micro Vickers hardness tester. From these results, the punch load and deformation characteristic of Al circular pipes were highly changed in the compressive strain rate about 200 mm/min. The Al circular pipes had the tendency that the punch load decreased with increasing the compressive strain rate. In addition, following as the change of the shape and position of neutral axis due to the deformation proceeding of the circular pipe, the special point of the internal circular pipe at maximum load showed the maximum deformation strain and the maximum measured hardness value. The CAE (computer aided engineering) simulation using Deform-2D program was performed on the circular pipe in order to know and verify the exact compressive deformation behavior. From these results, the experimentally measured results were reasonably in good agreement with the simulation results.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제29권3호
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• pp.173-181
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• 2003

Purpose : This study was intended to evaluate the positional relationship between the hyoid bone and the mandible in patients with mandibular protrusion after mandibular set-back surgery by means of 3D-CT. Materials and methods : Preoperative(3 weeks before) and postoperative (6 weeks after) 3D-CT & cephalogram were taken on 32 patients(12 male, 20 female, mean age of 23.2) treated by bilateral sagittal split osteotomy with rigid fixation. The angular measurement on 3D-CT basilar view were deviation of Me & H, long axis angle of left & right cornu majus. The lineal measurement on 3D-CT basilar view were composed of intercondylar line and coordinates(x,y) of Me & H. The angular & lineal measurement of lateral cephalogram were composed of mandibular plane angle, SNA, SNB, ANB, FH-NA & FH-NB, and coordinates(x,y) of B, Pog, Me & H, PAS, Lpw, MPH and IAS. On the frontal cephalogram, deviation of Me were evaluated. Results : The mean mandibular set-back was 8.0mm horizontally and mandibular plane angle was slightly increased. The hyoid bone was displaced postero-inferiorly, the distance between MP(mandibular plane) and H(hyoid bone) was increased and the posterior airway space values (PAS, Lpw, IAS) were decreased. The coordinates Me(x,y), H(x,y) and deviation angle Me'& H' were revealed the strong positive correlation. Conclusion : The results revealed that the horizontal, vertical and transverse relationship of the mandibular and the hyoid bone movements were significantly correlated in patients performed mandibular set-back surgery.

• Imaging Science in Dentistry
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• 제41권4호
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• pp.155-159
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• 2011

Purpose : This study was performed to determine the prevalence of maxillary canine impaction on a basis of a single panoramic radiograph in Bangladeshi population. Materials and Methods : A random sample of seven hundred panoramic radiographs was collected from the patient record of a dental clinic. All the selected panoramic radiographs were taken from January 2009 to August 2010 by a single panoramic radiograph machine with the same exposure time (19 seconds) for all radiographs. One hundred and twenty panoramic radiographs were excluded to minimize the selection bias. In a dim lit room, an observer assessed the radiographs on a standard radiographic light box. The position of the impacted maxillary canine was recorded in line with the longitudinal axis of a tooth using the edge of a metal ruler. Data were subsequently put on SPSS 11.5 software and chi-square (${\chi}^2$) tests were applied to find out the association. Results : Among 580 panoramic radiographs it was found that impacted maxillary canines were present in only 7 (1.2%) radiographs. A statistical significant difference was found between the age of the patients and the vertical position of the impacted canines (p=0.000) and between the age of the patients and the horizontal position of the impacted canines (p=0.003). Conclusion : The prevalence was found to be low compared with the present study from the limitation of panoramic image. Further study needs to include three-dimensional imaging modality.

• Imaging Science in Dentistry
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• 제38권1호
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• pp.23-27
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• 2008

Purpose: The aim of this study was to evaluate the change in the position of the mandibular condyle within articular fossa by a CBCT after wearing complete denture (CD). Materials and Methods: CBCT of 34 temporomandibular joints were taken from 9 male and 8 female patients with CB $Mercuray^{TM}$ (Hitachi, Japan) before and after wearing a CD for rehabilitation. Position of mandibular condyle within articular fossa at centric occlusion was evaluated with $Vimplant2.0^{TM}$ (CyberMed, Korea) on the central parasagittal view and curved panoramic coronal view of the condylar head. A statistical evaluation was done with SPSS. Results: The range of anteroposterior positional rate (AP) of condylar head within articular fossa was -16-5 and -10-12 respectively on the right and left sides. Before wearing CD, the AP rate showed discrepancy between right and left sides (p<0.05). After wearing CD, both condyles showed a tendency to decrease in posterior condylar position (right side; p<0.05). The average discrepancy between right and left side in mediolateral positional rate (MD) was 15.5 and 4.5 respectively before and after wearing CD. The improvement was observed in mediolateral relationship of both condylar heads after wearing CD (p< 0.01). Before wearing CD, the average horizontal angle of long axis of condylar head was $79.6{\pm}2.7^{\circ}\;and\;80.1{\pm}5.7^{\circ}$ respectively on the right and left sides. After wearing CD, both condyles were rotated in the same direction in average on axial plane. Conclusion: We observed with CBCT the significant clinical evidence in case of positional change of mandibular condyle after wearing complete denture.

• Steel and Composite Structures
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• 제35권4호
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• pp.475-494
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• 2020

Presented are experimental results from 24 full-scale push test specimens to study the behaviour of composite beams with trapezoidal profiled sheeting laid transverse to the beam axis. The tests use a single-sided horizontal push test setup and are divided into two series. First series contained shear loading only and the second had normal load besides shear load. Four parameters are studied: the effect of wire mesh position and number of its layers, placing a reinforcing bar at the bottom flange of the deck, normal load and its position, and shear stud layout. The results indicate that positioning mesh on top of the deck flange or 30 mm from top of the concrete slab does not affect the stud's strength and ductility. Thus, existing industry practice of locating the mesh at a nominal cover from top of the concrete slab and Eurocode 4 requirement of placing mesh 30 mm below the stud's head are both acceptable. Double mesh layer resulted in 17% increase in stud strength for push tests with single stud per rib. Placing a T16 bar at the bottom of the deck rib did not affect shear stud behaviour. The normal load resulted in 40% and 23% increase in stud strength for single and double studs per rib. Use of studs only in the middle three ribs out of five increased the strength by 23% compared to the layout with studs in first four ribs. Eurocode 4 and Johnson and Yuan equations predicted well the stud strength for single stud/rib tests without normal load, with estimations within 10% of the characteristic experimental load. These equations highly under-estimated the stud capacity, by about 40-50%, for tests with normal load. AISC 360-16 generally over-estimated the stud capacity, except for single stud/rib push tests with normal load. Nellinger equations precisely predicted the stud resistance for push tests with normal load, with ratio of experimental over predicted load as 0.99 and coefficient of variation of about 8%. But, Nellinger method over-estimated the stud capacity by about 20% in push tests with single studs without normal load.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.396-401
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• 2004

In this paper, a 1MW HAWT(FIL-1000) rotor blade has been designed by BEMT(Blade Element Momentum Theory) with Prandtl's tip loss. Also, a 3-D flow and performance analysis on the FIL-1000 rotor blade has been carried out by using the 3-D Navier-Stokes commercial solver (CFX-5.7) to provide more efficient design techniques to the large-scale HAWT engineers. The rated power and itsapproaching wind velocity at design point (TSR=7.5) are 1MW and 9.99m/s respectively. The rotor diameter is 54.5m and the rotating speed is 26.28rpm. Airfoils such as FFA W-301, DU91-W-250, DU93-W-210, NACA 63418, NACA 63415 consist of the rotor blade from hub to tip. Recent CFX version, 5.7 was adopted to simulate 3-D flow field and to analyze the performance characteristics of the rotor blade. Entire mesh node number is about 730,000 and it is generated by ICEM-CFD to achieve better mesh quality The predicted maximum power occurringat the design tip speed ratio is 931.45kW. Approaching to the root, the inflow angle becomes large, which causesthe blade to be stalled in the region. Therefore, k-$\omega$ SST turbulence model was used to predict the quantitative flow information more accurately. Application of commercial CFD code to optimum blade design and performance analysis was proved to be more effective environment to HAWT blade designers.

• 한국추진공학회지
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• 제18권4호
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• pp.43-49
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• 2014

국소적 정상초음파장의 교란이 관내 메탄/공기 예혼합화염의 전파속도 및 화염구조에 미치는 영향을 규명하기 위한 실험적 연구를 수행하였다. 슐리렌가시화기법을 이용하여 정상초음파 유무에 따른 화염선단 발달과정의 변이를 상세히 관찰하였다. 정상초음파가 개재할 때, 기연부에서 가로방향의 줄무늬가 생성되었고, 연소반응의 촉진으로 화염의 속도는 증가하였으며, 화염의 발달과정이 부력의 영향으로부터 자유로워져 화염선단의 상하 대칭성을 유지하려는 경향을 보인다.