• 한국공간구조학회논문집
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• 제7권6호
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• pp.61-68
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• 2007

대공간구조에서 접합부의 신뢰도는 매우 중요하다. 접합부에 사용되는 고력볼트의 나사부 유효단면적은 축부단면적보다 작고 볼트 축부에 락핀용 구멍이 있기 때문에 볼트 나사부 또는 락핀용 구멍에 응력집중 현상이 발생하여 취성 파단이 발생할 우려가 높다. 특히 접합부는 직렬형 구조로 이루어져 있다. 따라서 접합부에서의 극한상황시 파괴유형은 필히 취성파괴를 피해야 하며 연성파손으로 유도해야 한다. 따라서 본 연구에서는 볼 조인트 접합부의 소성변형능력을 향상시키고 현장에서 발생할 수 있는 시공오차의 흡수가 가능하도록, 볼트의 나사부나 핀부의 취성파단 없이 소성변형능력 향상을 목표로 하였다. 에너지흡수형 볼트를 사용함으로써 소성변형능력이 향상된 스페이스 프레임의 접합상세를 제안하였다.

• Journal of Oral Medicine and Pain
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• 제48권4호
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• pp.152-158
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• 2023

Purpose: This pilot study aimed to evaluate changes in joint space (JS) using cone-beam computed tomography (CBCT) images of patients diagnosed with temporomandibular joint (TMJ) osteoarthritis (OA) and to determine the association between occlusal changes and JS. Methods: CBCT images were used to measure the anterior, superior, and posterior JSs of the sagittal plane. The differences in JS values over time and between groups were compared. The percentage change in the anteroposterior position of the mandibular condyle between groups was also analyzed. Results: Thirty-four subjects (mean age=43.91±20.13), comprising eight males (23.5%) and 26 females (76.5%), were divided into 18 patients with no change in occlusion (NCO) and 16 patients with a change in occlusion (CO) during TMJ OA. The JS measurements of the study subjects showed a decrease in anterior joint space (AJS) values over time. There was no difference in JS measurements between the groups at T1 and T2. AJS values measured at T1 were lower in the CO group than in the NCO group, but the difference was not statistically significant. In both groups, a posterior position of the mandibular condyle was initially observed with high frequency. However, there is a statistically significant difference in CBCT images taken after occlusal changes, with an increased frequency of condyles observed in the anterior or central positions. Conclusions: In conclusion, AJS decreased over time in TMJ OA, and the mandibular condyle became more anteriorly positioned with occlusal changes. Therefore, clinicians should diligently monitor mandibular condyle morphology and JS using CBCT, along with the patient's clinical symptoms, to treat and control TMJ OA effectively.

• Journal of Mechanical Science and Technology
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• 제16권8호
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• pp.1053-1063
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• 2002

This paper presents a robust nonlinear controller for a f degree of freedom (DOF) parallel manipulator in the task space coordinates. The proposed control strategy requires information on orientations and translations in the task space unlike the joint space or link space control scheme. Although a 6 DOF sensor may provide such information in a straightforward manner, its cost calls for a more economical alternative. A novel indirect method based on the readily available length information engages as a potential candidate to replace a 6 DOF sensor. The indirect approach generates the necessary information by solving the forward kinematics and subsequently applying alpha-beta-gamma tracker With the 6 DOF signals available, a robust nonlinear task space control (RNTC) scheme is proposed based on the Lyapunov redesign method, whose stability is rigorously proved. The performance of the proposed RNTC with the new estimation scheme is evaluated via experiments. First, the results of the estimator are compared with the rate-gyro signals, which indicates excellent agreement. Then, the RNTC with on-line estimated 6 DOF data is shown to achieve excellent control performance to sinusoidal inputs, which is superior to those of a commonly used proportional-plus-integral-plus-derivative controller with a feedforward friction compensation under joint space coordinates and the nonlinear controller under task space coordinates.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 1999년도 제1회 학술대회논문집(KIASC 1st conference 99)
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• pp.89-92
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• 1999

A small scale joint sample of Nb3Sn CICC was fabricated by sub-cable to sub-cable joining. This joint was produced by parallel insertion of one end of each sub-cable into the sub-cable space of the other side of cable, which can decrease the equivalent electrical resistance at the joint is expected to have average properties, dc resistance and ac losses, in view of the shapes of ITER type joint and strand to strand joint. The 3.8nOhm of dc resistance was measured in the range of 10-200A transport current. The normalized resistivity of the joint was about 6.7 $\mu}$Ohm-$^mm{2}$. Considering the normalized resistivity, the full scale joint prepared by sub-cable to sub-cable joining may have similar joint dc resistance with other conventional full scale joints with a shorter joining length.

• 대한기계학회논문집
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• 제18권1호
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• pp.85-92
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• 1994

With the wide application of fiber-reinforced composite meterial in aircraft space structures and robot arms, the design and manufacture of composite joints have become a very important research area because they are often the weakest areas in composite structure. In this paper, the torque transmission capacities of the adhesive tubular single lap joint and double lap joint were studied. The stress and torque transmission capacity of the adhesive joints were analyzed by the finite element method and compared to the experimental results. The torque capacity of the double lap joint was increased 2.7 times over that of the single lap joint. Also, the fatigue limit of the double lap joint was increased 16 times over that of the single lap joint.

• 대한견주관절학회:학술대회논문집
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• 대한견주관절학회 2004년도 연수강좌
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• pp.176-179
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• 2004

Arthroscopy of the stiff elbow joint is a technically difficult procedure because of the decreased joint space of the elbow joint. even to experienced surgeons. Problems encountered include limited access of instrument to the intra-articular ,pace and an increased risk of cartilage injury in the contracted elbow joint. This study describes a novel transarticular approach for elbow arthroscopy that allow, the safe and effective creation of the proximal medial and lateral portals.

• ETRI Journal
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• 제26권5호
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• pp.384-390
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• 2004

We propose a new bandwidth-efficient technique that achieves high data rates over a wideband wireless channel. This new scheme is targeted for a multiple-input multiple- output orthogonal frequency-division multiplexing (MIMO-OFDM) system that achieves transmit diversity through a space frequency block code and capacity enhancement through the iterative joint processing of zero-forcing detection and maximum a posteriori (MAP) decoding. Furthermore, the proposed scheme is compared to the coded Bell Labs Layered Space-Time OFDM (BLAST-OFDM) scheme.

• 대한물리의학회지
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• 제11권1호
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• pp.93-105
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• 2016

PURPOSE: The purpose of this study was to determine the effect of corrective exercise on hip joint range of motion, lower limb alignment, radiographs of hip and knee joints, and quadriceps muscle activity in a patient with knee joint valgus deformity. METHODS: A single-subject A-B-A experimental design was used to determine the effects of therapeutic exercise. The single-subject was a 27-year-old male, who presented with knee joint valgus deformity. Corrective exercise program was performed for 40 min/day twice a week for 12-week. Range of motion (hip flexion, extension, abduction, adduction, internal rotation, and external rotation), lower limb alignment test (Q-angle, rear foot alignment, and leg length), standing anterior-posterior radiographs (neck shaft angle and knee joint space), and quadriceps muscle activity of both lower limbs were measured before (A 1), after 6 weeks (B 1) and after 12-weeks (B 2) of corrective exercise and after 6 weeks of exercise completion (A 2). RESULTS: Hip range of motion increased in all directions of both sides at B 2 and A 2 compared to at A 1. Q-angle of both side and leg length discrepancy decreased at B 2 and A 2 compared to at A 1. Neck shaft angle and knee joint space of both sides improve at B 2 and A 2 compared to at A 1. Quadriceps of both side muscle activities improved at B 2 and A 2 compared to at A 1. CONCLUSION: We demonstrated that corrective exercise increases range of motion, and improves lower limb alignment and muscle activity in a patient with knee joint valgus deformity.

• 한국터널지하공간학회 논문집
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• 제3권2호
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• pp.3-12
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• 2001

본 논문은 절리암반 터널의 안정성 해석을 위한 2차원 개별요소모델링방법에 대한 개선방안을 제안하였다. 먼저, 절리군과 터널의 상대방위를 고려하여 터널단면상에서 불연속거동이 가능한 절리군을 구별하는 기준을 제시하였다. 이 기준에 따라 불연속거동이 가능한 절리군은 개별요소(암석블록)의 변이 되도록 하고 그 외 절리군은 암석블록의 탄성특성을 보정하는 방법을 제시하였다. 또한, 주어진 절리의 기하학적 특성에 대해서 절리의 방위편차와 유한길이를 고려한 복잡한 모델과 절리의 평균방위와 무한길이를 고려한 단순한 모델의 특성을 분석하였다. 그 결과, 후자의 모델이 일관성 있는 터널의 국부적 파괴양상과 명료한 암반의 불연속거동을 보여줌으로써 터널설계목적에 적절함을 확인하였다.

• 한국생산제조학회지
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• 제25권6호
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• pp.492-497
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• 2016

Teaching an industrial robot is still a dangerous and time-consuming process. It is expected that a robot can track a trajectory that is repeatedly taught by a human operator. Teaching a robot in joint space is easier than that in Cartesian space or a work space because the robot will never lose its stability when it is taught and operated in a joint space. However, it is very easy for a robot to lose its stability when it is taught in a work space. This is because of the singular points problem in kinematics for manipulators. Thus, experts should teach a given task to a robot in a careful manner. A new algorithm that avoids the problem of singular points is proposed. Using this proposed method, a user can freely teach a robot without the chance of instability in an entire work space.