• 대한치과보철학회지
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• 제31권4호
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• pp.580-610
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• 1993

The purpose of this study was to analyse the deflection and stress distribution at the supporting bone and it's superstructure by the alteration of angulation between implant and it's implant abutment. For this study, the free-end saddle case of mandibular first and second molar missing would be planned to restore with fixed prosthesis. So the mandibular second premolar was prepared for abutment, and the cylinder type osseointegrated implant was placed at the site of mandibular second molar for abutment. The finite element stress analysis was applied for this study. 13 two-dimensional FEM models were created, a standard model at $0^{\circ}$ and 12 models created by changing the angulation between implant and implant abutment as increasing the angulation mesially and distally with $5^{\circ}$ unittill $30^{\circ}$. The preprocessing decording, solving and postprocessing procedures were done by using FEM analysis software PATRAN and SUN-SPARC2GX. The deflections and von Mises stresses were calculated under concentrated load (load 1) and distributed load(load 2) at the reference points. The results were as follows : 1. Observing at standard model, the amount of total deflection at the distobuccal cusp-tip of pontic under concentrated load was largest of all, and that at the apex of implant was least of all, and the amount of total deflection at the buccal cusp-tip of second premolar under distributed load was largest of all, and that at the apex of implant was least of all. 2. Increasing the angulation mesially or distally, the amounts of total deflection were increased or decreased according to the reference points. But the order according to the amount of total deflection was not changed except apex of second premolar and central fossa of implant abutment under concentrated load during distal inclination. 3. Observing at standard model, the von Mises stress at the distal joint of pontic under concentrated load was largest of all, and that at the apex of implant was least of all. The von Mises stress at the distal margin of second premolar under distributed load was largest of all, and that at the apex of Implant was least of ail. 4. Increasing the angulation of implant mesially, the von Mises stresses at the mesial crest of implant were increased under concentrated load and distributed load, but those were increased remarkably under distributed load and so that at $30^{\circ}$ mesial inclination was largest of all. 5. Increasing the angulation of implant distally, the von Mises stresses at the distal crest of implant were increased remarkably under concentrated load and distributed load, and so those at $30^{\circ}$ distal inclination were largest of all.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제25권4호
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• pp.324-329
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• 1999

The facial esthetics are much affected by nasal changes due to especially its central position in relation to facial outline and so appropriately evaluated should be the functional and esthetic aspects of the nose associated with the facial appearance. Generally, a maxillary surgical movement is known to induce the changes of nasolabial morphology secondary to the skeletal repositioning accompanied by muscular retraction. These changes can be desirable or undesirable to individuals according to the direction and amount of maxillary repositioning. We investigated the surgical changes of bony maxilla and its effects to nasal morphology through the analysis of the lateral cephalogram in the Le Fort I osteotomy. Subjects were 10 patients(male 2, female 8, mean age 22.3 years) and cephalograms were obtained 2 weeks before surgery(T1) and 6 months after surgery(T2). The surgical maxillary movement was identified through the horizontal and vertical repositioning of point A. Soft-tissue analysis of the nasal profile was performed employing two angles: nasal tip projection(NTP), columellar angle(CA). Also, alar base width(ABW) was assessed directly on the patients with a slide gauge. The results were as follows; 1. Both anterior and superior movement above 2mm of maxilla rotated up nasal tip above 1mm. Either anterior or superior movement above 2mm of maxilla made prediction of the amount & direction of NTP changes difficult. Especially, a correlation between horizontal movement of maxilla and NTP rotated-up was P<0.01. 2. Both much highly anterior and superior movement of maxilla is accompanied by more CA increase than either highly. Especially, the correlation between horizontal movement of maxilla and CA change was P<0.05. 3. Anterior and/or superior movement of maxilla was accompanied by the unpredictable ABW widening. 4. The amount of changes of NTP, CA, and ABW is not in direct proportion to amout of anterior and/or superior movement of maxilla. 5. Nasal morphologic changes following Le Fort I osteotomy are affacted by not merely bony repositioning but other multiple factors.

• 대한토목학회논문집
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• 제31권4C호
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• pp.117-125
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• 2011

최근 신뢰성 높은 지반조사를 실시하기 위하여 국부적인 영역에서 해상도 높은 데이터의 획득이 가능한 전기비저항의 활용이 증가하고 있다. 본 연구의 목적은 온도 효과를 고려하여 보다 신뢰성 높은 전기비저항 값의 획득을 위한 현장용 온도 보상형 전기비저항 프로브의 개발 및 현장 적용성 평가이다. 프로브에 삽입된 온도센서는 온도전이 실험결과와 실험시 안정성 등을 고려하여 선단부로부터 15mm, 30mm, 그리고 90mm 지점에 부착하였고, 프로브 관입시 지반의 교란과 기하학적 형상을 고려하여 콘 형태로 제작하였으며 선단부의 각도는 $60^{\circ}$로 결정하였다. 현장실험에 사용되는 표준 콘과의 비교를 위하여 직경은 표준 콘과 동일한 35.7mm로 제작하였으며, 관입 속도도 동일하게 20mm/sec로 적용하였다. 관입 실험 시, 콘이 지반에 관입 되는 순간 약 $4^{\circ}C$의 온도 변화를 관찰하였으며 이를 보정하여 표준 콘에서 획득한 값과 비교하면 전기비저항을 이용한 지반조사시 반드시 온도에 대한 영향을 고려해야 함을 알 수 있었다. 본 연구에서는 현장용 온도보상형 전기비저항 프로브의 개발 및 현장검증을 통하여 관입 실험 시 온도 보정이 반드시 필요함을 보여준다.

• 폴리머
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• 제36권2호
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• pp.155-162
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• 2012

전기방사 방법으로 sulfonated poly(ether ether ketone) (SPEEK) 나노섬유를 제조하고, 압축성형법으로 고분자 전해질막 연료전지(polymer electrolyte membrane fuel cell, PEMFC)용 나노섬유막을 제조하였다. SPEEK의 최대 설폰화율은 95% 이었고 초기 열분해 온도는 약 $280^{\circ}C$로 PEEK 보다 낮았으며 접촉각은 설폰화도가 증가함에 따라 감소하였다. 전기방사 나노섬유의 최적 인가전압, 유속, 방사거리(tip to collector distance, TCD) 및 농도는 각각 22 kV, 0.3 mL/hr, 5 cm, 23 wt% 이었고 평균 섬유직경은 47.6 nm 이었다. 한편, SPEEK 이온교환 나노섬유막의 함수율 및 이온교환용량은 설폰화 시간과 설폰화제 함량이 증가함에 따라 증가하였으며 최적값은 각각 20%, 2.03 meq/g으로 Nafion 117 보다 우수하였다. 막의 전기저항은 설폰화 시간이 증가함에 따라 감소하였고 그 값은 0.58~0.06 ${\Omega}{\cdot}cm^2$로 측정되었다. 또한 막의 수소이온전도도는 설폰화 시간이 증가함에 따라 증가하였으며 최대 0.099 S/cm로 Nafion 117 보다 우수하였다.

• Clinical and Experimental Otorhinolaryngology
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• 제11권4호
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• pp.275-280
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• 2018

Objectives. Middle vault deviation has a significant effect on the aesthetic and functional aspects of the nose, and its management continues to be a challenge. Spreader graft and its modification techniques have been focused, but there has been scarce consideration for removing surplus portion and balancing the upper lateral cartilage (ULC). This study aimed to report the newly invented triangular-shaped resection technique ("triangular resection") of the ULC and to evaluate its efficacy for correcting middle vault deviation. Methods. A retrospective study included 17 consecutive patients who presented with middle vault deviation and underwent septorhinoplasty by using triangular resection at a tertiary academic hospital from February 2014 and March 2016. Their outcomes were evaluated pre- and postoperatively including medical photographs, acoustic rhinometry and subjective nasal obstruction using a 7-point Likert scale. Results. The immediate outcomes were evaluated around 1 month after surgery, and long-term outcomes were available in 12 patients; the mean follow-up period was 9.1 months. Nasal tip deviation angle was reduced from $5.66^{\circ}$ to $2.37^{\circ}$ immediately (P<0.001). Middle vault deviation also improved from $169.50^{\circ}$ to $177.24^{\circ}$ (P<0.001). Long-term results were $2.49^{\circ}$ (P=0.015) for nasal tip deviation and $178.68^{\circ}$ (P=0.002) for middle vault deviation. The aesthetic outcome involved a complete correction in eight patients (47.1%), a minimally visible deviation in seven patients (41.2%) and a remaining residual deviation in two patients (11.8%). Pre- and postoperative minimal cross-sectional areas (summation of the right and left sides) were 0.86 and 1.07, respectively (P=0.021). Fifteen patients answered about their nasal obstruction symptoms and the median symptom score had alleviated from 6.0 to 3.0 (P=0.004). Conclusion. Triangular resection of the ULC is a simple and effective method for correcting middle vault deviation and balancing the ULCs without complications as internal nasal valve narrowing.

• Journal of Korean Dental Science
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• 제4권1호
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• pp.1-5
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• 2011

Purpose: Exact knowledge of the location and dimension of the pulp chamber help to maintain the pulp healthy during operative procedure and also reduces the risk of perforation of pulp chamber during root canal treatment. This in-vivo study was carried out to measure critical morphology of pulp chamber of mandibular molar using intra-oral periapical radiograph. Materials and Methods: Mandibular molar teeth of 56 patients were evaluated. The mandibular molar teeth whose pulp chamber was not violated by caries, restoration, fracture crown and those having closed apex were included in the study. The intraoral periapical radiographs were taken with paralleling angle technique using radio-opaque grid with 1 mm space. This grid was placed directly on the film. Results: In 94% of the mandibular first molars specimens the pulp chamber ceiling was at the level of the cemento-enamel junction. The measurements showing the lowest percentage variance were buccal cusp to furcation (approximately 11%) and buccal cusp to pulp chamber ceiling (approximately 15%). The distance from the cusp tip to pulp chamber ceiling height was approximately 6.0 mm, the distance from the pulpal floor to the furcation was approximately 3.0 mm, and the average height of a pulp chamber was 1.5 to 2.0 mm. Conclusion: The exact knowledge of distances of pulp chamber from various anatomical landmarks helps in proper assessment of root canals and ultimately avoids the failure of root canal treatment.

• Journal of Biosystems Engineering
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• 제10권1호
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• pp.13-23
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• 1985

Spraying method from the paddy-field levee is known to give insufficient penetration of the spray droplets to the rice stem of the densely grown plants, which is generally encountered at the last stage of rice growth. This study was intended to investigate the spraying system to solve this existing problem. As an approach, it was attempted to develop the boom-with-nozzle, between-the-row application system. Several types of nozzles and their different arrangements in the boom were tested in the field to measure the penetration-reaching distance and the uniformity of spray droplet distribution. The results of the study are summarized as follows: 1. Field experiments by the spraying method from the paddy-field levee showed to have practically no penetration of the spray droplets to the portion of the plant stem with the normal flow volume generally applied and thus need for improving present spraying method. 2. It was found that, considering both the uniformity of the spray droplet distribution and performance rate, the most efficient type of nozzle in the between-the-row boom-type spraying system was one that has core-insert hollow-cone with some clearance between the cone and tip. 3. When tested by applying the spraying method of between-the-row, the nozzle pressure did not affect the uniformity of spray droplet distribution. However, the nozzle pressure had a positive effect on the penetrating-reaching distance of the facing side of the rice stem and did not affect much on that of the opposite face of the stem. It was also found that the maximum pressure to affect the penetration-reaching distance was about $10kg/cm^2$. 4. The uniformity of the spray droplet distribution in the between-the-row system was greatly affected by the height and orientation of the nozzles in the boom. Based on experimental work for the different type of the boom-with-nozzle arrangements, it is recommended that the position of nozzle is set at about 0.45 m above the ground and two nozzles in the boom are oriented to be faced with each other with some angle such that the droplet stream from the nozzle would not directly face with each other.

• 대한치과의사협회지
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• 제53권5호
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• pp.368-376
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• 2015

Purpose : The objective of this research was to develop a more simplified drilling procedure with an enhanced implant drill. Materials and Methods : The drill enhanced design factors enabled implantation of Dia. 5.0mm fixture with only 2 times drilling which is more simplified drilling procedure. The enhanced drill was designed with 2 flutes, 2-phase or 3-phase formed drill tip and 25 degrees of helix angle. The proposed drilling procedure (2 times) was compared with a general drilling process (4 times) in terms of temperature changes, cutting time and ISQ value. Results : The simplified drilling procedure indicated less heat than a conventional drilling procedure (p<0.05). The enhanced drill showed significantly shorter drilling time than a conventional drill (p<0.05). On the other hand, higher insertion torque and ISQ value were observed on the the suggested drilling procedure than the conventional drilling procedure (p<0.05). Conclusion : A simplified drilling procedure with the newly designed drill could provide higher effectiveness and safety of dental implant operations under properly controlled external conditions, such as irrigation and RPM of drilling.

• 한국운동역학회지
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• 제12권1호
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• pp.173-191
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• 2002

The purpose of this study was defined efficient throw motion pattern to obtain the quantitative data and to achieve successful bowling through kinetic - kinematic variables on the throw motion. Subject of group composed of three groups : Higher bowlers who are two representative bowlers with 200 average points and one pro-bowler. Middle bowlers who are three common persons with 170 average points. Lower bowler who are three common persons with 150 average points. Motion analysis on throw motion in three groups respectively has been made through three-dimension cinematography using DLT method. Two high-speed video camera at operating 180 frame per secondary. One-way ANOVA has been used to define variable relations. Analyzed result and conclusion are the following : The displacement of back of the hand must have wider difference of each right-left displacement to increase the spin of the ball. In high bowlers group, difference between the front-rear position of back of the hand in case of success and that in case of failure in follow throw is 0.17m. That is to say, momentum in case of success come to increase greatly, compared with that in case of failure. To increase the spin of the ball, the potential difference should be narrower in follow through. In case of the high bowlers, the velocity of the front-rear direction of the back of the hand has been the fastest both in release and follow through, compared with those in other groups, which has contributed to increasing the spin force of the ball. The orders in the resultant velocity of the back of the hand has shown the this : the finger tip$\rightarrow$the back of the hand$\rightarrow$wrist.These orders made the proximal segment support the distal segment. The distal segment has provided the condition to accelerate the velocity. In case of failure, the suddenly increased velocity has caused the failure in the follow through. Acutely flexing the angle of the back of the hand has contributed to lifting to increase the spin of the ball.

• 대한기계학회논문집B
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• 제35권1호
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• pp.67-73
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• 2011

본 연구는 DME-바이오디젤 혼합연료의 분무 및 연소, 배기 특성을 바이오디젤과 비교한 실험적 연구이며 실험연료는 바이오디젤 (BD100)과 중량 기준으로 DME를 20% 혼합한 DME-바이오디젤 혼합연료 (B-DME20)이다. 거시적 분무 특성을 연구하기 위하여 분무 이미지로부터 분무도달거리, 분무각을 측정하였으며, 연소 및 배기 특성은 단기통 직접 분사식 압축착화 기관을 이용하여 분석하였다. 실험결과 바이오디젤과 DME-바이오디젤 혼합연료는 분사율에서는 큰 차이가 없었지만 혼합연료의 경우에 착화지연기간이 짧고 연소압력이 높았으며soot 배출물이 현저하게 줄어들었다.