• 대한산업공학회지
• /
• 제27권4호
• /
• pp.413-423
• /
• 2001

Low back disorders (LBDs) are one of the most common and costly work-related musculoskeletal disorders. One of the major possible risk factors of LBDs is to work with static and awkward trunk postures, especially in a complex trunk posture involving flexion, twisting and lateral bending simultaneously. This study is to examine the effect of complex trunk postures on the postural stresses using a psychophysical method. Twelve healthy male students participated in an experiment, in which 29 different trunk postures were evaluated using the magnitude estimation method. The results showed that subjective discomfort significantly increased as the levels of trunk flexion, lateral bending and rotation increased. Significant interaction effects were found between rotation and lateral bending or flexion when the severe lateral bending or rotation were assumed, indicating that simultaneous occurrence of trunk flexion, lateral bending and rotation increases discomfort ratings synergistically. A postural workload evaluation scheme of trunk postures was proposed based on the angular deviation levels from the neutral position. Each trunk posture was assigned numerical stress index depending upon its discomfort rating, which was defined as the ratio of discomfort of a posture to that of its neutral posture. Four qualitative action categories for the stress index were also provided in order to enable practitioners to apply corrective actions appropriately. The proposed scheme is expected to be applied to several field areas for evaluating trunk postural stresses.

• 한국통신학회논문지
• /
• 제34권3C호
• /
• pp.268-273
• /
• 2009

홍채 인식은 홍채 패턴 정보를 이용하여 사람의 신원을 확인하는 생체 인식 기술이다. 이러한 홍채 인식 시스템에 있어 조명의 영향이나 동공의 크기, 머리의 기울어짐 등으로 인해 발생될 수 있는 홍채 패턴의 변화에 대해 무관한 특징을 추출하는 것은 중요한 과제이다. 본 논문에서는 국부적 방향 히스토그램을 이용해 조명의 변화나 홍채의 회전에 강인한 홍채인식 방법을 제안하였다. 제안된 방법은 특징 추출 및 특징 비교 시 회전에 대해 별도의 처리가 필요하지 않아 고속의 특징 추출 및 특징 비교가 가능하며 성능도 기존의 방법과 대등함을 실험을 통하여 확인하였다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 추계학술대회논문집 II
• /
• pp.817-825
• /
• 2001

The natural frequencies of a flexible spinning disk misaligned with the axis of rotation are studied in an analytic manner. The effects of misalignment on the natural frequency need to be investigated, because the misalignment between the axis of symmetry and the axis of rotation cannot be avoided in the removable disks such as CD-R, CD-RW or DVD disks. Assuming that the in-plane displacements are in steady state and the out-of-plane displacement is in dynamic state, the equations of motion are derived for the misaligned spinning disk. After the exact solutions are obtained for the steady-state in-plane displacements, they are plugged into the equation for the dynamic-state out-of-plane motion. The resultant equation is a linear equation for the out-of-plane displacement, which is discretized by the Galerkin method. Based on the discretized equations, the effects of the misalignment are analyzed on the vibration characteristics of the spinning disk, i.e., the natural frequencies and the critical speed

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
• /
• 제14권8호
• /
• pp.763-767
• /
• 2008

본 논문에서는 모바일 환경에서의 3D 그래픽 처리에 효과적인 고성능/저전력의 CORDIC 구조를 구성하기 위하여 각도 기반 검색(ABS)과 스케일링 효과를 고려한 검색(SCS)과 같은 두 가지 오프라인 벡터링 방법을 제안하고 이를 통해 연산의 반복횟수를 줄이는 알고리즘을 개발한다. ABS 알고리즘은 3차원 벡터를 두 각으로 표현하고 이를 검색의 기준으로 삼았고, SCS 알고리즘은 단위 벡터를 기준으로 하여 벡터 회전 시에 최소의 반복 연산만으로도 원하는 회전을 수행할 수 있는 최적의 기본각 회전 시퀀스를 오프라인으로 미리 검색하여 적용한다 본 논문에서 제안하는 ABS, SCS 알고리즘을 통해 지연을 각각 50% 감소시킬 수 있었으며, 이와 함께 voltage scaling 기술을 적용하여 전력 소모를 크게 감소시킬 수 있음을 논의한다.

• 한국유체기계학회 논문집
• /
• 제17권4호
• /
• pp.53-58
• /
• 2014

Vacuum pump transfers waste that is pulverized by integrated macerator. For this reason, unlike ordinary pump systems, there is a rotating macerator ahead of impeller for pulverizing. It is hard to predict numerical solution because area of Inlet flow path changes according to the rotation angle of the integrated macerator. So, in this study, the verification of performance evaluation method of Marine vacuum pump were numerically studied by commercial ANSYS CFX 13.0 software. We select a model of performance evaluation for study, and we analyze change of inlet flow path of integrated macerator according to rotation angle. We generate 5 model sets according to rotation angle of the integrated macerator. And we evaluate their performance by numerical analysis. Then, we analyze internal flow field and performance according to rotation angle of the integrated macerator based on numerical analysis result. In addition, we compared with experimental data for validity of numerical result by using steady state analysis.

• 천문학회보
• /
• 제45권1호
• /
• pp.60.3-61
• /
• 2020

We perform disk-halo decomposition of the Large Magellanic Cloud (LMC) using a novel HI velocity field extraction method, aimed at better deriving its HI kinematics and thus the dark matter density profile. For this, we use two newly developed galaxy kinematic analysis tools, BAYGAUD and 2DBAT which have been used for the kinematic analysis of resolved galaxies from Australian Square Kilometre Array (ASKAP) observations like WALLABY which is an all-sky HI galaxy survey in southern sky. By applying BAYGAUD to the combined HI data cube of the LMC taken with the Australia Telescope Compact Array (ATCA) and Parkes radio telescopes, we decompose all the line-of-sight velocity profiles into an optimal number of Gaussian components based on Bayesian MCMC techniques. From this, we disentangle turbulent non-circular gas motions from the overall rotation of the galaxy. We then derive the rotation curve of the LMC by applying 2DBAT to the separated circular motions. The rotation curve reflecting the total kinematics of the LMC, dark and baryonic matters is then be combined with the mass models of baryons, mainly stellar and gaseous components in order to examine the dark matter distribution. Here, we present the analysis of the extracted HI gas maps, rotation curve, and J, H and K-band surface photometry of the LMC.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.2457-2460
• /
• 2003

There is a great demand to manipulate biological cell autonomously since biologist should spend much time to obtain skillful manipulation techniques. For this purpose, we propose a cell chip to control, carry, fix and locate the cell. In this paper, we focus on the cell rotator to rotate individual biological cell based on a micro fluidics technology. The cell rotator consists of injection hole and rotation well to rotate a biological cell properly. Under the variation of flow rate in injection hole, the angular velocity of a biological cell is evaluated to find the feasibility of the proposed rotation method. As a practical experiment, Zebrafish egg is employed. Based on this research, we find the possibility of non-contact rotation way that can highly reduce the damage of the biological cell during manipulation. To realize an autonomous biological cell manipulation, a cell chip with manipulation well and micro channel in this research will be utilized effectively in near future.

• Clinics in Shoulder and Elbow
• /
• 제3권1호
• /
• pp.26-32
• /
• 2000

Purpose : The aim of this study is the assessment of the clinical outcomes after percutanous pinning of unstable two-parts fracture of surgical neck in humerus. Materials and Methods: This study was based on thirteen cases of non-comminuted unstable surgical neck fracture of humerus among 19 cases, which followed-up more than one year. Follow-up averaged 29 months. We treated with percutaneous pinning techniques and assessed clinical outcomes. Functional evaluation was performed using the standard method of research committee of American Shoulder and Elbow Surgeons(ASES). Results: Last follow-up ROM of shoulder joint were 142 degrees of forward elevation, 57 degrees of external rotation, 72 degrees of external rotation in 90 degrees abduction, and T8 of internal rotation. Pain scale was l(range : 0∼3). ASES scores was 86.2(range : 63.3~98.3). Patient satisfaction based on ASES were excellent in 6 cases, good in 5 cases, fair in 1 case, poor in 1 case. A case of fair result was caused by limitation of motion in shoulder joint and poor case was paraplegia patient after traffic accident. Conclusion : Percutaneous pinning is recommended for non-comminuted unstable fracture of surgical neck in humerus.

• Steel and Composite Structures
• /
• 제22권3호
• /
• pp.613-625
• /
• 2016

The joints of the new prefabricated concrete assemble beam-column joints are put together by the hybrid joints of inserting steel under post-tensioned and non-prestressed force and both beams and columns adopt prefabricated components. The low cyclic loading test has been performed on seven test specimens of beam-column joints. Based on the experimental result, the rotation capacity of the joints is studied and the $M-{\theta}$ relation curve is obtained. According to Eurocode 3: Design of steel structures and based on the initial rotational stiffness, the joints are divided into three types; by equivalent bending-resistant stiffness to the precast beam, the equivalent modulus of elasticity $E_e$ is elicited with the superposition method; the beam length is figured out that satisfies the rigid joints and after meeting the requirements of application and safety, the new prefabricated concrete assemble beam-column joints can be regarded as the rigid joints; the design formula adopted by the standard of concrete joint classification is theoretically derived, thereby providing a theoretical basis for the new prefabricated concrete structure.

• 제어로봇시스템학회논문지
• /
• 제22권2호
• /
• pp.83-88
• /
• 2016

In this paper, a design method for a logistics transportation robot based on a modular conveyor rack and path planning considering the environment of a logistics center is proposed. The driving part of the logistics transportation robot is designed and the working method of lifter for the transportation function is explained. The design of the modular conveyor rack is also described and an algorithm for a logistics transportation robot using a modular conveyor rack is suggested. The $A^*$ algorithm is improved by using the concept of rotation cost and the initial state of the transportation robot's characteristics. We experimented with a four-step transportation algorithm for a logistics transportation robot using a modular conveyor rack and showed that the proposed method can be used successfully in a logistics center. In addition, we verified the effectiveness of the improved $A^*$ algorithm considering the rotation cost and the initial state of the robot.