• 한국운동역학회지
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• 제28권3호
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• pp.181-185
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• 2018

Objective: The purpose of this study was to investigate the effect of types of drive-in initial steps in basketball on technical factors, to provide basic information for the enhancement of basketball skill. Method: Ten men (age: $24.70{\pm}2.26years$; height: $181.00{\pm}5.72cm$; weight: $75.70{\pm}8.23kg$; career length: $10.00{\pm}3.59years$), each with a career length of over five years and no history of injury to the lower extremities within the prior six months, participated in this study. They were asked to perform four types of drive-in movements at $35{\sim}60^{\circ}$, wearing their own shoes, after running from a start line 5 m away and catching a basketball passed by an expert passer. The drive-in movements were measured by eight infrared cameras (Oqus 300, Qualisys, Sweden). Collected raw data were used to calculate total initial step time, displacement, velocity, center of mass (COM) height, and COM velocity. Results: Total initial step displacement and velocity of cross drive-ins (JC, SC) were greater than that of direct drive-ins (JD, SD; p < .05). COM velocity of cross drive-ins (JC, SC) was also greater than that of direct drive-ins (JD, SD; p < .05). Conclusion: Our results indicated that cross drive-ins, regardless of stop step type, are more effective than direct drive-ins. This is because cross drive-ins are technically bold due to less influence from walking violations and double dribble rules in basketball. However, using one-sided movement is too difficult to play in competitive game; therefore, basketball players should develop the ability to choose appropriate movement frequency.

• 한국전산구조공학회논문집
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• 제18권3호
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• pp.277-289
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• 2005

본 논문은 강사장교의 극한강도를 다루고 있다. 강사장교의 극한강도를 평가하기 위하여 비선형 비탄성 해석 접근법과 분기점 좌굴 고유치해석 접근법인 유효접선탄성계수$(E_f)$법을 사용하여 예제를 수행하였다. 이를 위하여 초기형상을 고려한 실용적인 비선형 비탄성 해석기법을 제시하였다. 초기형상 해석 시각 형상해석 단계마다 보-기둥 부재의 부재력 대신 개선된 구조물형상을 고려하였다. 보-기둥 부재의 기하학적 비선형은 안정함수를 사용하여 고려하였고, 재료적 비선형은 CRC 접선계수와 포물선 함수를 사용하여 고려하였다. 또한, 케이블 부재의 기하학적 비선형은 할선탄성계수 값을 사용하여 고려하였다. 본 연구에서 제안한 해석기법으로 예측된 하중-변위 곡선들이 다른 연구에 의한 결과들과 비교 검증 되었으며, 제시된 3차원 강사장교 모델들에 대하여 제안한 해석기법과 비탄성 좌굴해석을 사용하여 극한강도를 비교하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2003년도 춘계공동학술대회논문집
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• pp.21-26
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• 2003

지금까지의 탄성설계 개념에서 진전하여 소성을 고려한 탄소성 설계 개념의 설계적용이 필요하다 본 연구에서는 선체의 대표적인 구조물인 판을 대상으로 일반적인 하중형증분법 및 변위형증분법과 같은 비선형해석 기법과 호장증분법과 Newton-Raphson법을 병용한 증분형해법을 비교하였다. 특히. 초기처짐의 형태에 따른 해석을 통하여 초지처짐의 형상에 따른 판의 탄소성거동을 규명하였다 압축하중을 받는 박판구조물은 초기좌굴후 거동과 2차좌굴후 거동이 구조물 전체에 미치는 영향이 매우 크며 이러한 복잡한 거동을 구하기 위해서 해석방법으로는 범용 유한요소해석 프로그램인 ANSYS를 이용하였고 특히 호장증분법은 좌굴점에서의 복잡한 비선형 거동을 추정하기 위하여 적용하였다.

• 한국전산구조공학회논문집
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• 제25권4호
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• pp.347-354
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• 2012

형상기억합금의 복원력 및 복원량은 열 하중 및 기계적 하중으로 인한 마르텐사이트 상에서 오스테나이트 상으로의 상변이에 의한 상변형률 발생에 기인한다. 복원력 및 복원량은 초기 형상 및 하중 부여 방식에 따라 차이가 발생하는데 적절한 설계 전략없이 상변형률에만 의지한 경우 큰 복원력은 발생할 수 있어도 큰 복원량을 기대하기는 어렵다. 이는 형상기억합금의 큰 복원력과 작은 복원량 간의 비대칭성에 기인하며 형상기억합금의 효율적인 이용에 걸림돌이 된다. 본 연구에서는 형상기억합금의 상변이로 발생하는 복원량을 극대화하는 방안으로 형상기억합금 선이 이중으로 감겨있는 이중 나선 구조 형상기억합금 스프링을 제안한다. 그리고 열 하중에 의해 발생하는 복원량을 예측하고 단일 나선 구조 형상기억합금 스프링과 비교 분석하여 이중 나선 구조 형상기억합금 스프링이 단일 나선 구조 형상기억합금 스프링보다 성능 비대칭성을 보다 완화시킬 뿐만 아니라 복원력 대비보다 큰 복원량을 가짐을 보였다.

• Clinics in Shoulder and Elbow
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• 제24권1호
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• pp.9-14
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• 2021

Background: Recent studies about completely displaced midshaft clavicle fractures have reported that their nonunion/malunion rates were significantly higher in conservatively treated patients compared to surgically treated patients. The purpose of this study was to evaluate the factors associated with treatment decisions for midshaft clavicle fractures and also the factors that affect patient satisfaction with their treatment choice. Methods: We retrospectively reviewed the records of 75 patients who had been diagnosed with a midshaft clavicle fracture and were treated conservatively at a single institution between March 1, 2013, and December 31, 2014. Their medical records were reviewed to investigate the severity of the initial vertical displacement. A telephone survey was carried out to identify the presence of any patient-perceived deformity and determine if the patient eventually underwent surgery and whether the patient would prefer surgery if the injury recurred. Results: Significantly more patients with vertical displacement ≥100% (9/28) eventually underwent surgery compared to patients with vertical displacement <100% (3/32, p=0.028). Patients with vertical displacement ≥100% (13/28) were significantly more likely to prefer surgery compared to patients with vertical displacement <100% (7/32, p=0.044). Among the conservatively treated patients, nine of 32 participants with a patient-perceived deformity and one of 16 without a patient-perceived deformity responded that they would prefer to receive surgery in same situation in the future (p=0.079). Conclusions: Patients with a midshaft clavicle fracture with vertical displacement of ≥100% may eventually require surgical treatment. When conservative treatment is carried out, the long-term patient results may be unsatisfactory due to perceived residual deformities.

• Geomechanics and Engineering
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• 제14권5호
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• pp.459-466
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• 2018

By conducting uniaxial loading cycle tests on the coal rock with outburst proneness, the dilatation characteristics at different loading rates were investigated. Under uniaxial loading and unloading, the lateral deformation of coal rock increased obviously before failure, leading to coal dilatation. Moreover, the post-unloading recovery of the lateral deformation was rather small, suggesting the onset of an accelerated failure. As the loading rate increased further, the ratio of the stress at the dilatation critical point to peak-intensity increased gradually, and the pre-peak volumetric deformation decreased with more severe post-peak damage. Based on the laboratory test results, the lateral deformation of the coals at different depths in the #1302 isolated coal pillars, Yangcheng Coal Mine, was monitored using wall rock displacement meter. The field monitoring result indicates that the coal lateral displacement went through various distinct stages: the lateral displacement of the coals at the depth of 2-6 m went through an "initial increase-stabilize-step up-plateau" series. When the coal wall of the working face was 24-18 m away from the measuring point, the coals in this region entered the accelerated failure stage; as the working face continued advancing, the lateral displacement of the coals at the depth over 6 m increased steadily, i.e., the coals in this region were in the stable failure stage.

• 한국생산제조학회지
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• 제24권2호
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• pp.251-255
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• 2015

Thermal deformation, such as bending and twisting, occurs among the polymer parts of air-conditioner indoor units because of repetitive temperature change during heating operation. In this study, a numerical method employing finite-element analysis to efficiently simulate the thermal deformation of an assembly is proposed. Firstly, the displacement of an actual assembly produced by thermal deformation was measured using a 3D optical measurement system. The measurement results indicated a general downward sag of the assembly, and the maximum displacement value was approximately 1 mm. The temperature distribution was measured using a thermographic camera, and the results were used as initial-temperature boundary conditions to perform temperature-displacement analysis. The simulation results agreed well with the measured data. To reduce the thermal deformation, the stiffness increased 100%. As the results, the maximum displacement decreased by approximately 5.4% and the twisting deformation of the holder improved significantly.

• 한국지반공학회논문집
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• 제33권2호
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• pp.17-26
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• 2017

해상구조물, 송전탑 등을 지지하는 말뚝기초는 바람, 조류, 파랑 등의 영향으로 횡방향 반복하중을 지배적으로 받으며, 이는 말뚝 주변 지반에 영구수평변위를 발생시켜 구조물의 안정성 및 기능성을 저해한다. 본 연구에서는 횡방향 반복하중에 의해 발생하는 말뚝의 영구수평변위를 평가하기 위하여, 서로 다른 세 가지 상대밀도(40%, 70%, 90%)로 조성된 건조 및 포화 모래지반에서 모형말뚝시험을 수행하였다. 모형시험 결과, 모든 시험조건에서 말뚝에 재하 된 횡방향 반복하중은 말뚝 주변 지반에 영구수평변위를 발생시켰다. 누적된 영구수평변위의 크기는 말뚝에 재하되는 횡방향 반복하중의 크기 및 재하횟수가 증가함에 따라 증가하였지만, 1회 재하로 인하여 발생되는 영구수평변위의 증가량은 점차 감소하였다. 또한, 말뚝에 발생하는 영구수평변위는 지반의 상대밀도가 클수록 작게 발생하고, 지반이 포화되면 크게 발생되는 것으로 평가되었다. 추가적으로, 누적 영구수평변위를 최초 재하 시 발생한 영구수평변위로 정규화한 영구수평변위를 평가하였으며, 이를 모래지반의 상대밀도, 횡방향 반복하중의 재하횟수에 관한 식으로 나타내었다.

• 대한치과교정학회지
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• 제18권2호
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• pp.367-385
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• 1988

In case of skeletal Class III malocclusion with underdeveloped maxilla, the extraoral orthopedic force for the stimulation of maxillary growth or anterior reposition of the maxilla has been used clinically for the improvement of facial skeletal relationship. The purpose of this investigation was to examine the initial reaction of maxillofacial complex to the maxillary protraction by using extraoral orthopedic force. The dried human skull was used and this investigation was done by means of double exposure holographic interferometry. The protraction forces placed on the canine or the first molar were parallel, $10^{\circ}$ downward, $20^{\circ}$ downward to the occlusal plane. Fringe pattern of each protraction condition was compared and analized. The results were as follows: 1. Each maxillofacial bone displaced saparately. 2. More displacement was shown at the area of the teeth and the alveolar bone. 3. A counterclockwise rotation of the maxilla wa decreased by downward protraction and especially 20 degree downward protraction from the canine showed least rotation. 4. On the zygomatic arch, outward bend was observed and this effect was decreased by downward protraction. 5. On the zygomatic bone, the counter clockwise rotation was increased by the downward protraction. 6. When maxillary expansion was applied at the same time, outward and upward displacement with counterclockwise rotation was observed on the maxilla. 7. The lateral pterygoid plate of sphenoid bone was affected by maxillary protraction.

• Structural Engineering and Mechanics
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• 제59권3호
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• pp.431-454
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• 2016

In this paper, the nonlinear static and free vibration analysis of Euler-Bernoulli composite beam model reinforced by functionally graded single-walled carbon nanotubes (FG-SWCNTs) with initial geometrical imperfection under uniformly distributed load using finite element method (FEM) is investigated. The governing equations of equilibrium are derived by the Hamilton's principle and von Karman type nonlinear strain-displacement relationships are employed. Also the influences of various loadings, amplitude of the waviness, UD, USFG, and SFG distributions of carbon nanotube (CNT) and different boundary conditions on the dimensionless transverse displacements and nonlinear frequency ratio are presented. It is seen that with increasing load, the displacement of USFG beam under force loads is more than for the other states. Moreover it can be seen that the nonlinear to linear natural frequency ratio decreases with increasing aspect ratio (h/L) for UD, USFG and SFG beam. Also, it is shown that at the specified value of (h/L), the natural frequency ratio increases with the increasing the values amplitude of waviness while the dimensionless nonlinear to linear maximum deflection decreases. Moreover, with considering the amplitude of waviness, the stiffness of Euler-Bernoulli beam model reinforced by FG-CNT increases. It is concluded that the R parameter increases with increasing of volume fraction while the rate of this parameter decreases. Thus one can be obtained the optimum value of FG-CNT volume fraction to prevent from resonance phenomenon.