• 전기학회논문지
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• 제64권7호
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• pp.1012-1018
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• 2015

The studies on the operating performance analysis or design about the fixed tilt angle flat-plate photovoltaic (PV) system are still lively going off. However the operating property analysis about the arch type PV system which means PV array were designed as round type is dissatisfied. In this paper, we theoretically established the factors which are cause of the deterioration in performance of arch type PV system. In addition, we use the Solar Pro simulation tools to design both flat-plate type and arch type 30kW PV systems. The simulations about arch type PV system applied two ways such as central inverter and string inverter were conducted. The performance ratio (PR) of the PV system with flat-plate type shows the highest value 74[%] when the tilt angle is 30°. In case of arch type, when applying central inverter method, PR value shows approximately 73[%] and no more difference with arch type of the PV array. This value shows 1[%] decrease compare with the flat-plate type. However when applying string inverter methods, the average PR value shows 80 % and 6% improved than the central inverter method.

• 대한치과보철학회지
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• 제41권1호
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• pp.61-70
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• 2003

The purpose of this study was to investigate the contact angles and wettability of conventional dental stones and improved dental stones and newly developed dental stones on several impression materials. Materials included in this study were several dental stones and newly developed dental stone ; 2 type III stones (Snow Rock, New Diastone), 6 type IV stones(Crystal Rock, Vel Mix, Fuji Rock, Tuff Rock, Resin Rock and newly developed dental stone) and 1 type V stone (Die Keen). Contact angles on the impression materials were measured with contact angle measuring device. Ten specimens for each material, total 180 specimens were made on void entrapment model. The two impression materials (Handae, GC) were used to produce 9 groups of die stone casts form void entrapment model. Voids in the stone casts were counted under a stereoscopic microscope. The grad for the reproduction ability of each materials on the void entrapment model was calculated from the casts by one examiner. From the experiment, the following results were obtained : 1. The newly developed stones showed smallest contact angle. Type III dental stone had larger contact angles than type IV and V stones. Contact angle was much affected by the impression materials. 2. Resin containing die materials such as Tuff Rock and Resin Rock had smallest void number than any other groups. 3. In comparing reproduction parameters, Tuff Rock and Resin Rock presented superior results, while Vel Mix showed lowest reproduction ability.

• 한국융합학회논문지
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• 제8권7호
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• pp.219-224
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• 2017

본 논문은 탄소섬유로 구성된 아치형태의 시험편에 인장각도가 작용할 때 내부의 섬유구조에서 발생되는 등가응력과 변형량에 관한 것이다. CFRP는 무수히 많은 각 섬유가 하나의 축으로 작용하며 이를 통해 금속과 비교할 때 높은 비강도와 비강성을 가질 수 있다. 본 연구에서 사전연구에 의해 최적 적층각도는 $60^{\circ}$로 구성된 아치형 구조에서 반경에 따른 응력분포를 결과를 검토하며 같은 적층각도에서 그 반경이 증가할수록 내구성이 낮아짐을 알 수 있다. 이를 통해 본 연구 결과를 적층 각도에 따른 아치형 구조의 설계에 적용함으로써, 파손방지와 내구성 향상을 위한 안전설계에 기여할 수 있으며, 패드 형상의 디자인적인 요소를 융합기술에 접목하여 그 미적인 감각을 나타낼 수 있다.

• 대한족부족관절학회지
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• 제11권2호
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• pp.226-231
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• 2007

Purpose: To evaluate the clinical outcomes and radiographic results of open reduction and internal fixation for intraarticular calcaneal fractures. Materials and Methods: We reviewed 20 cases of calcaneal fractures managed with open reduction and internal fixation from March 2003 to January 2005. We used the computed tomographic classification system proposed by Sanders et al to classify these fractures. Preoperative and postoperative Bohler's angle, heel height (calcaneal facet height) and calcaneal length, calcaneal width were measured. The Creighton-Nebraska Health Foundation Assessment score was used for clinical evaluation. Results: There were 12 cases of type II fractures, 5 of type III fractures and 3 of type IV fractures. The mean clinical score was 84.3 for type II, 82.6 for type III and 56.1 for type IV. The mean preoperative $B{\ddot{o}}hler$ angle was $6.1^{\circ}$ and final was $22.8^{\circ}$. The mean preoperative calcaneal facet height was 76.6 mm and final was 80.3 mm (The mean calcaneal facet height was changed from preop 76.6 mm to postop 80.3 mm). The mean preoperative calcaneal length was 88.2 mm and final was 92.6 mm. The mean preoperative width was 38.1 mm and final was 35.6 mm. Conclusion: Open reduction and internal fixation showed good results for type II and III fractures, but for type IV fractures the clinical result was significantly worse than the other types. However, type IV fractures still had restoration of (should be restored in) $B{\ddot{o}}hler's$ angle, calcaneal facet height, calcaneal length and width which may be helpful in later subtalar fusion.

• 복식
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• 제62권1호
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• pp.76-89
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• 2012

This study was performed to offer the basic data for the design of farm shoes. 265 Korean female farmers aging between the 40s to the 80s volunteered for this study and we measured 40 items on each foot with the 3D foot scanner. First, the differences between farmers' feet and non-farmers' feet were analyzed. Farmers' feet were thicker in the instep areas, but had lower arch height than non-farmers' feet. In addition, farmer's feet were tilted to the inside. Next, eight factors were extracted among the 40 measuring items, and the classification criteria of the foot shape was analyzed. The important factors were: size of foot length and volume of ankle, malleolus height and size, volume of the front part of ankle, medial & lateral ball width, and vertical size of foot. Third, three clusters according to the foot shapes were categorized by cluster analysis of eight factor scores. Foot type 1 was medium in foot length, big in thickness, large in lateral ball width, small in toe 1 angle, and tilted to the inside. Foot type 2 was long and slim, and big in toe 5 angle. Foot type 3 was short in foot length, medium in volume of the front part of ankle, large in medial ball width, and big in toe 1 angle. Despite its shortness, foot type 3 was thick and showed severe deformation in toe 1. Lastly, the frequency distributions of the foot types in each age group were analyzed. Female farmers of the forties showed high frequency in type 1 and other age groups showed high frequency in type 2. The older female farmers showed higher frequency of type 3.

• 한국산학기술학회논문지
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• 제14권6호
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• pp.2773-2779
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• 2013

본 연구에서는 인체의 대퇴부 두께에 따른 다양한 무릎뼈의 굴곡각도가 가능하고 사용이 편리한 새로운 보조기구를 개발하고 유용성을 평가하고자 하였다. 검사 대상자는 연구 목적에 동의하고 과거 무릎 관련 질병이 없는 정상인 중 넙다리 둘레가 얇은 A 그룹과 두꺼운 B 그룹을 선발하였다. 무릎뼈의 축방 영상을 획득하기 위해 무릎굴곡각도를 $5^{\circ}$씩 증가시켜 $35^{\circ}$, $45^{\circ}$, $55^{\circ}$로 설정하였으며, 각 각도별로 X-선 입사각도를 $40^{\circ}$, $50^{\circ}$, $60^{\circ}$로 변화시켜 9 개의 검사 조합으로 검사하였다. 그 결과, 사용이 편리하고 체형변화에 적응할 수 있도록 다양한 무릎관절 각도가 가능한 검사대 일체형 무릎뼈 방사선영상검사 보조장비를 개발하였다. 그리고 이 보조장비를 이용하여 A 그룹에서는 무릎굴곡 각도가 $45^{\circ}$에서 X-선 입사 각도가 $60^{\circ}$와 $50^{\circ}$ 그리고 B 그룹에서는 X-선 입사 각도가 $60^{\circ}$에서 무릎굴곡 각도가 $35^{\circ}$와 $45^{\circ}$에서 우수한 영상이 도출되었다. 향후 다양한 체형의 환자들의 검사에 매우 유용할 것으로 사료된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.802-804
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• 2002

An analysis of the skeleton type BLDC motor is presented. The single phase skeleton type BLDC motor consists of the stator, rotor with the permanent magnet, and drive circuit with hall sensors that detect the rotor position. The major factors for the initial starting, efficiency, and torque ripples of the skeleton type BLDC motor are the detent groove of the stator and the lead angle of the phase voltage. The performance characteristics according to the angle and height of the detent groove is analyzed. The optimum lead angles of the phase voltage with the torque ripple and motor efficiency is described using the finite element method.

• 한국자동차공학회논문집
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• 제9권1호
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• pp.20-27
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• 2001

A variable configuration tracked vehicle(VCTV) is developed to reduce turning energy and improve climbing ability for stairs. This mechanism has four track T-type frames. By changing the driving direction, each track T-type frame rotates to minimize the contact area with ground. It also has better performance than other VCTV in energy consumption of turning. Futhermore this mechanism is more stable than other VCTV on the rough terrain. When climbing stairs, each track T-type frame rotates to obtain a front attack angle and keep stability on steep stairs. The design parameters of components of track T-type frames are optimized to enhance the performance of climbing stairs. Performance indices include a stable angle, a climbing ability, a height of the vertical obstacle. In case that the overall length of the mechanism is 0.2m, it is required that the radius of the wheels should be 5mm and the length track contacted with he ground should be 0.09m to climb higher and steeper stairs.

• 자원환경지질
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• 제31권6호
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• pp.547-555
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• 1998

A new trigonometrical method for calculating total slip (T) of faulting is presented. The parameters for the calculations are used rake of fault striation, strike and dip of fault and of index planar structure such as bedding plane. The faults are groupped into three types. The direction of plunging of fault striation is out of a range ${\pm}90^{\circ}$ to the bedding dip direction in $360^{\circ}$ system, which is groupped into the type I. Meanwhile, the case of the direction lies in the above range can be separated into two different types, type II and type III, according to relative largeness of the angles rake of fault striation and i (see text). The type II has smaller rake than angle i and the type III has larger rake than angle i. Here I propose a few equations for calculating not only total slip (T) but strike slip (L) or dip slip (S) of the faulting. The equations are adapted selectively to the types of fault mentioned before. The limitation of the method is that the equations do not fit to polyphase faulting.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.873-878
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• 2000

Semiconductor packaging technology is changed rapidly according to the trends of the micro miniaturization of multimedia and information equipment. For I/O limitation and fine pitch limitation, DIP and SOP/QFP are replaced by BGA/CSP. This is one of the surface mount technology(SMT). Solder ball is bumped n the die pad and connected onto mounting board. In ball bump formation, vacuum suction type ball alignment process is widely used, However this type has some problems such as ionization, static electricity and difficulty of fifo(first-input first-out) of solder balls. Seesaw type is reducing these problems and has a structural simplicity and economic efficiency. Ball cartridge velocity and ball aligned plate angle are Important variables to improve the ball alignment Process. In this paper, seesaw-type CSP solder ball loader is developed and the optimal velocity and plate angle are proposed.