• 대한치과보철학회지
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• 제43권4호
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• pp.528-543
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• 2005

Statement of problem: Repeated delivery and removal of abutment cause some changes such as wear, scratch or defect of hexagonal structure. It may increase the value of rotational freedom(RF) between hexagonal structures. Purpose: The purpose of this study was to evaluate surface changes and rotational freedom between the external hexagon of the implant fixture and internal hexagon of abutment after repeated delivery and removal under SEM and toolmaker's microscope. Materials and methods: Implant systems used for this study were 3i and Avana. Seven pail's of implant fixture, abutment and abutment screws for each system were selected and all fixtures were perpendicularly mounted in liquid unsaturated polyesther with dental surveyor. Each one was embedded beneath the platform of fixture. Surfaces of hexagonal structure before repeated closing and opening of abutment were observed using SEM and rotational freedom was measured by using toolmaker's microscope. Each abutment was secured to the implant future by each abutment screw with recommended torque value using a digital torque controller and was repeatedly delivered and removed by 20 times respectively. After experiment, evaluation for the change of hexagonal structures and measurement of rotational freedom were performed. Result : The results were as follows; 1. Wear of contact area between implant fixture and abutment was considerable in both 3i and Avana system. Scratches and defects were frequently observed at the line-angle of hexagonal structures of implant fixture and abutment. 2. In the SEM view of the external hexagon of implant fixture, the point-angle areas at the corner edge of hexagon were severely worn out in both systems. It was more notable in the case of 3i systems than in that of Avana systems. 3. In the SEM view of the internal hexagon of abutment, Gingi-Hue abutment of 3i systems showed severe wear in micro-stop contacts that were machined into the corners to prevent rotation and cemented abutment of Avana systems showed wear in both surface area adjacent to the corner mating with external hexagon of implant fixture. 4 The mean values of rotational freedom between the external hexagon of the implant fixture and internal hexagon of abutment were 0.48$\pm$0.04$^{\circ}$ in pre-tested 3i systems and 1.18$\pm$0.25$^{\circ}$ after test, and 1.80$\pm$0.04$^{\circ}$ in pre-tested Avana systems and 2.61$\pm$0.16$^{\circ}$ after test. 5. Changes of rotational freedom after test shouted statistical)y a significant increase in both 3i and Avana systems(P<0.05, paired t-test). 6. Statistically, there was no significant difference between amount of increase in the rotational freedom of 3i systems and amount of increase in that of Avana ones(P>0.05, unpaired t-test). Conclusion: Conclusively, it was considered that repeated delivery and remove of abutment by 20 times would not have influence on screw joint stability. However, it caused statistically the significant change of rotational freedom in tested systems. Therefore, it is suggested that repeated delivery and remove of abutment should be minimal as possible as it could be and be done carefully Additionally, it is suggested that the means or treatment to prevent the wear of mating components should be devised.

• 대한관절경학회지
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• 제7권1호
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• pp.92-95
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• 2003

34세 남자 환자로 등산중 실족으로 발생한 전방십자인대의 완전파열로 자가 슬괵건을 이용한 경핀 고정법으로 전방십자인대 재건술을 시행하였다. 술후 경과는 양호하였으나 술후 3개월째 굴신 신전 운동 시 슬부 후측면의 동통과 지속적인 관절내 부종 소견을 보였으며 수차례의 관절천자와 약물투여에도 반응이 없었다. 컴퓨터 단층 촬영 상후방 피질 골의 천공이 관찰되어 술후 6개월째 이차관절내시경 수술을 시행하였다. 내시경 소견상 경핀고정물의 전방부 1/3에 일치되는 투명한 이물질과 대퇴경골관절면의 연골의 손상이 관찰되었으며 이물 제거 후 증세는 호전되었다. 경핀 터널의 잘못된 위치가 실패의 원인이라고 생각되었으며 경핀고정법을 이용한 전방십자인대 재건술시, 슬관절 과굴곡 상태에서 예각의 대퇴 터널을 만들어 후방 피질 골을 두껍게 남기고, 핀 홀을 만들 때 경핀가이드를 횡상과축보다 $10\~20$도 외회전시켜야 대퇴골 후방피질골의 천공을 방지할 수 있어 조기 실패를 예방할 수 있다고 생각된다.

• 구강회복응용과학지
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• 제24권1호
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• pp.29-40
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• 2008

본 연구의 목적은 10-12세 성장기 아동에서 측두하악장애의 증상과 징후 및 부정교합의 유병율과 이의 상관관계에 대해 알아보고자 하였다. 연구를 위해 강릉시에 위치한 6개 초등학교의 10-12세 아동 465명(남자 233명, 여자 232명)을 대상으로 간이병력조사와 간이임상검사를 시행하였다. 조사 결과, 측두하악장애 증상 중 두통의 유병율(34.6%)이 가장 높았으며, 여자(40.4%)가 남자(28.8%)보다 유의성 있게 높았다. 그 밖의 측두하악장애 증상은 연령 증가에 따라 혹은 성별에 따라 유의한 차이가 없었다. 측두하악장애 징후 중 단순관절음의 유병율(32.9%)이 가장 높았으며, 연령 증가에 따라 유의한 증가를 보였다. 악관절 촉진시 측방 압통의 유병율은 18.1%이었으며, 연령 증가에 따라 유의한 증가를 보였다. 근육 촉진시 압통에서 교근의 유병율(15.1%)은 전측두근과 후측두근 보다 높았으며, 연령 증가에 따라 유의성 있는 증가를 나타냈다. 개구제한의 유병율은 30.3%를 차지하였으며, 연령 증가에 따라 유의성 있는 증가를 보였다. 모든 측두하악장애 징후의 유병율은 성별에 따른 유의한 차이를 보이지 않았다. Angle's I급 부정교합(73.3%)이 가장 흔하였으며, 다음으로 III급 (12.9%), II급 1류 (11%), II급 2류 (2.8%) 순을 보였다. 각각의 교합상태의 유병율은 성별에 따라 유의성 있는 차이는 없었다. 측두하악장애 증상 및 징후에 관련된 교합상태는 II급 1류와 III급 부정교합이었다 (p<0.05). 본 연구결과는 성장기 아동에서 측두하악장애 증상 및 징후가 높은 유병율을 나타내, 성장기 아동의 측두하악관절 평가가 중요함을 시사한다.

• 한국운동역학회지
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• 제12권2호
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• pp.51-63
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• 2002

본 연구는 200m 경기의 곡선주로에서 직선주로 진입 시 나타나는 운동학적 특성을 파악하기 위해 실시하였다. 이를 위해 단거리 육상선수 4명을 대상으로 실시하였으며 곡선주로에서 직선주로로 연결되는 구간 10m를 설정하여 비디오 카메라로 촬영하였다. 공간의 좌표를 이미알고 있는 통제점 틀을 사용하여 분석구간을 모두 포함할수있도록 설치하였으며 대상자 별로 5번씩 실시하여 이중 가장 좋은 기록을 보인 동작을 실제 분석하였다. 10m 구간에서 대상자들은 평균 4.5${\pm}$0.41번의 보폭을 보이는 것으로 나타났으며, 소요시간은 1.42${\pm}$0.04sec.를 보였다. 평균보폭의 신장비는 1.25${\pm}$0.20%를 보였으며, 평균속도는 7.06${\pm}$0.19m/s를 보였다. 곡선주로에서 직선주로로 연결되는 구간에서 인체중심변위는 곡선의 안쪽 코스를 따라 이동하고 있었으며 외측(오른쪽)에 위치하는 다리의 변위가 내측(왼쪽)에 위치하는 다리의 변위보다 크게 나타났다. 좌우측 손분절 속도에서 내측에 위치하는 왼손의 속도보다는 외측에 위치하는 오른손의 속도가 다소 빠르게 나타났는데, 곡선주로에서는 외측에 위치하는 팔의 속도를 크게하여 질주방향으로 나아가는 것으로 나타났다. 어깨관절각도는 상완이 전측에 위치할 때 보다는 후측에 위치할 때가 보다 큰 각도를 보이고 있었으며 몸통측면각도는 곡선주로의 외측에 위치하는 오른발이 이지할 때 보다는 내측에 위치하는 왼발이 이지할 때 더 작은 값을 보이고 있었으며 직선주로에 근접할수록 몸통 측면각도가 작아지는 것으로 나타났다. 몸통회전각은 외측에 위치하는 오른발이 지지할 때 몸통을 전방으로 회전시켜 나아가는 것으로 나타났다.

• 대한통합의학회지
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• 제8권4호
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• pp.223-230
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• 2020

Purpose : The purpose of this study was to examine the effects of tools (i., extracorporeal shock wave therapy, massage gun, and foam roller) on range of motion, muscle tone and pain threshold among patients with hamstring stiffness. Methods : Fourteen participants with hamstrings stiffness were recruited. Interventions were performed 6 times, and each session was for 30 seconds using the three tools. The range of motion, muscle tone, and pain threshold were measured. The order of the use of the three tools was randomly determined. The foam roller was made to move from the bottom of the hip crease to the upper part of the back of the hamstring. Additionally, velocity 5 vibration stimulation was performed on the hamstring using a massage gun. Moreover, vibration stimulation was performed on the hamstring with extracorporeal shock wave therapy 5 minutes, 5 Hz, and 1,500 strokes. The flexibility of the posterior thigh muscle was based on maintaining the knee and hip joints in a 90 ° bend in the supine position. The joint angle of the knee was measured, when the knee was actively extended, at the maximum point where the posterior thigh muscle was stretched. The elasticity of the posterior thigh muscle was measured while the subject was prone and in a relaxed state without any force. Measurements were made at the muscle abdominal area of the semitendinosus muscle of the posterior femur, and the area to be measured was marked with a pen. The measurement of the tenderness threshold of the posterior femur was measured using a tenderness meter(Commander Algometer, J-Tech, USA). The force value at the point at which the pressure sensation change to pain was measured after applying vertical pressure to the posterior femur muscle, which was the halfway point between the ischial tuberosity and the popliteal surface of the subject lying on their stomach. Results : The extracorporeal shock wave therapy increased stiffness and, muscle tone, and caused changes in the pain threshold, whereas the other two tools had no effect on these indices. Conclusion : Extracorporeal shock wave therapy has important effects on range of motion and muscle stiffness and can be used in warmup protocols.

• 한국운동역학회지
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• 제13권3호
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• pp.81-98
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• 2003

The purpose of this study is to closely examine kinematic characteristics by jump phase of Li Xiaopeng motion in horse vaulting and provide the training data. In doing so, as a result of analyzing kinematic variables through 3-dimensional cinematographic using the high-speed video camera to Li Xiaopeng motion first performed at the men's vault competition at the 14th Busan Asian Games, the following conclusion was obtained. 1. It was indicated that at the post-flight, the increase of flight time and height and twisting rotational velocity has a decisive effect on the increase of twist displacement. And Li Xiaopeng motion showed longer flight time and higher flight height than Ropez motion with the same twist displacement of entire movement. Also the rotational displacement of the trunk at peak of COG was much short of $360^{\circ}$(one rotation) but twist displacement showed $606^{\circ}$. Likewise, Li Xiaopeng motion was indicated to concentrate on twist movement in the early flight. 2. It was indicated that at the landing, Li Xiaopeng motion gets the hip to move back, the trunk to stand up and the horizontal velocity of COG to slow down. This is thought to be the performance of sufficient landing, resulting from large security of rotational displacement of airborne and twist displacement. 3. It was indicated that at the board contact, Li Xiaopeng motion made a rapid rotation uprighting the trunk to recover slowing velocity caused by jumping with the horse in the back, and has already twisted the trunk nearly close to $40^{\circ}$ at board contact. Under the premise that elasticity is generated without the change of the feet contacting the board, it will give an aid to the rotation and twist of pre-flight. Thus, in the round-oH phase, the tap of waist according to the fraction and extension of hip joint and arm push is thought to be very important. 4. It was indicated that at the pre-flight, Li Xiaopeng motion showed bigger movement than the techniques of precedented studies rushing to the horse, and overcomes the concern of relatively low power of jump through the rapid rotation of the trunk. Li Xiaopeng motion secured much twist distance, increased rotational distance with the trunk bent forward, resulting in the effect of rushing to the horse. 5. At horse contact, Li Xiaopeng motion makes a short-time contact, and maintains horse take-off angle close to vertical, contributing to the increase of post-flight time and height. This is thought to be resulted from rapid move toward movement direction along with the rotational velocity of trunk rapidly earned prior to horse contact, and little shave of rotation axis according to twist motion because of effective twist in the same direction.

• 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.

• Design & Manufacturing
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• 제14권1호
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• pp.8-14
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• 2020

In general, auto parts production assembly line is assembled and produced by automatic mounting by an automated robot. In such a production site, quality problems such as misalignment of parts (doors, trunks, roofs, etc.) to be assembled with the vehicle body or collision between assembly robots and components are often caused. In order to solve such a problem, the quality of parts is manually inspected by using mechanical jig devices outside the automated production line. Automotive inspection technology is the most commonly used field of vision, which includes surface inspection such as mounting hole spacing and defect detection, body panel dents and bends. It is used for guiding, providing location information to the robot controller to adjust the robot's path to improve process productivity and manufacturing flexibility. The most difficult weighing and measuring technology is to calibrate the surface analysis and position and characteristics between parts by storing images of the part to be measured that enters the camera's field of view mounted on the side or top of the part. The problem of the machine vision device applied to the automobile production line is that the lighting conditions inside the factory are severely changed due to various weather changes such as morning-evening, rainy days and sunny days through the exterior window of the assembly production plant. In addition, since the material of the vehicle body parts is a steel sheet, the reflection of light is very severe, which causes a problem in that the quality of the captured image is greatly changed even with a small light change. In this study, the distance between the car body and the door part and the door are acquired by the measuring device combining the laser slit light source and the LED pattern light source. The result is transferred to the joint robot for assembling parts at the optimum position between parts, and the assembly is done at the optimal position by changing the angle and step.

• 한국강구조학회 논문집
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• 제22권2호
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• pp.109-119
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• 2010

600MPa급 고강도 강관은 항복강도와 항복비에 대한 제한이 따른다. 현재 여러 기준에는 항복강도 360MPa 이하, 항복비 80% 이하를 사용하도록 권장하고 있다. 한계상태에서 고강도 강재의 압축세장비가 저강도 강재보다 작아져 압축지관의 좌굴발생이 야기되기 때문에 압축좌굴에 대한 거동을 이해하는 것은 필수적이다. 또한 각형강관에 대한 많은 실험데이터는 있지만 고강도 원형강관에 대한 실험은 많지 않다. 그래서 이 논문의 주된 목적은 실험에 앞서 원형강관을 유한요소 해석을 통하여 압축 좌굴과 고강도 강재의 접합부 한계상태식에 대한 검증을 통하여 600MPa와 400MPa 강재의 사용성을 알고자 하는 것이다. 이 해석은 구조물의 거동을 이해하기 위하여 폭두께비, 지관각도, 항복비, 편심을 주된 변수로 하여 범용프로그램인 아바쿠스를 사용하여 해석을 수행하였다. 그 결과 같은 하중에서 고강도 강재의 압축지관은 탄성좌굴이 발생하고 저강도 강재는 비탄성좌굴이 발생하는 것을 확인하였고 항복비가 80%이상인 경우 접합부가 취성파괴 되었다. 그리고 고강도 강재에서 주강관의 폭두께비를 변화시켰을 때 주관과 지관의 상대적인 폭두께비로 인해 해석값이 기준값보다 감소함을 알 수 있었다. 그러나 그 외 변수들로 인한 해석상 고강도 강재의 접합부 하중의 변화는 없는 것으로 확인하였다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제37권6호
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• pp.439-447
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• 2011

Introduction: In today's society, the rapid and appropriate care of the dental emergency patients is much more important. So, a retrospective study on the characteristics of emergency dental injuries and diseases will be very meaningful. Materials and Methods: This retrospective clinical study was carried by reviewing the radiographic films and emergency chart of 11,493 patients who had visited the emergency room of Hallym Sacred heart Hospital and were treated in the Department of Oral and Maxillofacial Surgery from January 2006 to December 2010. Results: The male to female ratio was 1.9:1. The highest monthly incidence was observed in May (10.4%) and June (8.9%) and the peak age distribution was the first decade (56.0%), followed by the second decade (16.0%). Trauma was the most common cause in dental emergency patients, followed in order by toothache, odontogenic infection, temporomandibular joint (TMJ) disorder and oral hemorrhage. Soft tissue injury was most prevalent in the trauma group, followed by tooth injury and facial bone fractures. In the tooth injury group, tooth fracture (56.7%) showed the highest incidence followed in order by tooth subluxation (18.2%), tooth concussion (16.9%), tooth avulsion (11.5%) and alveolar bone fractures (3.7%). In the facial bone fracture group, mandibular fractures (81.8%) showed the highest incidence followed in order by maxilla fractures (15.7%), nasal bone fractures (9.0%), zygomaticomaxillary complex fractures (5.4%), orbital bone fractures (2.5%). In mandibular bone fractures, the most common location was the symphysis (70.1%), followed in order by the mandibular angle (33.0%), mandibular condyle (22.8%) and mandibular body (13.6%). In the infection group, a submandibular space abscess (46.2%) was most common followed in order by a buccal space abscess (17.4%), canine space abscess (16.9%) and submental space abscess (12.3%). TMJ dislocation (89.3%) showed the highest incidence in the TMJ disorder group, followed by TMJ derangement (10.7%). In the other group, a range of specific symptoms due to post operation complications, trigeminal neuralgia, chemical burns and foreign body aspiration were reported. Conclusion: For the rapid and appropriate care of the dental emergency patients, well-organized system should be presented in oral and maxillofacial surgery. And it is possible under analysis of pattern and the variation of the dental emergency patients.