• Korean Journal of Crystallography
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• v.15 no.1
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• pp.29-34
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• 2004

The crystal structure of cholesteryl hemisuccinate ($C_{31}H_{50}O_4$) was investigated by X-ray diffraction method. The cholesterol fragment of the title compound were in good agreement with those for related cholesterol derivatives. The unit cell contains four cholesteryl hemisuccinate molecules that are not related by crystal symmetry and have their tetracyclic system almost parellel to each other. There are two pairs of hydrogen-bonded dimer between A and D molecules and B and C molecules. These two hydrogen-bonded dimers are parallel to the c-axis, and are closely packed.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.10a
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• pp.345-350
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• 2004

In this paper we study the controllability for the nonlinear fuzzy integro-differential equations on E$_{N}$$^{n}$ by using the concept of fuzzy number of dimension n whose values are normal, convex, upper semicontinuous and compactly supported surface in R$^n$. E$_{N}$$^{n}$ be the set of all fuzzy numbers in R$^n$ with edges having bases parallel to axis X$_1$, X$_2$, …, X$_{n}$ .X> .

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2420-2422
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• 2004

In this paper, we developed a miniaturized humanoid having the new joint mechanism. In general, the high torque actuator and the joint mechanism having three coincided axes are important in development of the miniaturized humanoid. By using the swash plate, which is generally used in three axes rotor mechanism, we developed a new three-coincided-axes joint mechanism and a miniaturized humanoid having the joint mechanism at its hip and ankle joints. Since the joint mechanism has a pair of parallel drive motors for each axis, the driving torque of the joint mechanism is very high. Futhermore, thanks to the three-coincided-axes mechanism, the solution of the inverse kinematics is simple and computationally efficient, and the resulting walking behavior of the humanoid becomes natural.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1144-1148
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• 1991

The problems occurred when developing a automatic wheel deburring system are to make effective flexibility in model change and the irregularity of the position/shape of the burr, to select optimal robotic manufacturing process and to develope optimal end effector. The locations where burr exists are on flange, rim and spoke. Here will be discussed the optimal solution for the removal of rim burr by using robot. The research can be summarized as the automatic robot path generation by recognizing rim contour and automatic deburring process technique. Various rim contour data is generated automatically when the sensor which is fixed to robot is moving with the parallel motion to the wheel center axis and this generated data is transferred to the data storage system and converted to the robot path data. The robotic tool system which is suitable to the rim deburring process is developed by integrating tool, compliance function and sensor. And factory automation system controlled by robot controller and PC is developed. This system shows good productivity and flexibility.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.125-130
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• 1991

This paper presents a tracking filter using pseudomeasurements in an estimated line-of-sight Cartesian coordinate system(ELCCS) whose x-axis is on the line-of-sight to an estimated target position. A target dynamics model and a measurement equation in the ELCCS are derived first and then a tracking filter in the ELCCS named moving coordinate tracking filter(MCTF) is proposed. It is shown that this MCTF is equivalent to a Kalman filter in the inertial Cartesian coordinate system which is widely used in the target tracking system. By approximating the MCTF for a pseudomeasurement noise and an error covariance matrix in the ELCCS, decoupling of three axes can be achieved. In this case, named decoupled moving coordinate tracking filter(DMCTF), computation time can be drastically reduced by utilizing its parallel structure. Finally, the stochastic properties of the MCTF and DMCTF are presented. Especially, a sufficient condition of nondestabilizing deviation for the DMCTF is proposed. The performance of the MCTF and DMCTF are compared with a conventional Kalman tracking filter.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.180-184
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• 2004

The tribological behavior of carbon epoxy composites whose surfaces have many small grooves of $100\mu m$ width was experimentally investigated with respect to the sliding direction against groove orientation, surface pressure (P) and velocity (V). The wear mechanism of the composites was observed to calculate the wear volume with respect to the friction coefficient using scanning electron microscopic (SEM). Experimental results show that the abrasive wear is dominant wear mechanism for the grooved composite surface and the friction and wear are greatly reduced when the sliding direction is parallel to the axis of groove because abrasive particles are removed through the grooves effectively.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.106-108
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• 2002

Recent advances in radiation transport algorithms, computer hardware performance, and parallel computing make the clinical use of Monte Carlo based dose calculations possible. Monte Carlo treatment planning requires accurate beam information as input to generate accurate dose distributions. The procedures to obtain this accurate beam information are called "commissioning", which includes accelerator head modeling. In this study, we would like to investigate how much accurately Monte Carlo based dose calculations can predict the measured beam data in various conditions. The Siemens 6MV photon beam and the BEAM Monte Carlo code were used. The comparisons including the percentage depth doses and off-axis profiles of open fields and wedges, output factors will be presented.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.6
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• pp.1-7
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• 2008

This paper research the trend of technology of the high efficient and reliability machining center and high flexibility parallel manipulator machining center including linear motor machining center, submicron machining center and direct drive 5 axis machining center using patent information of Korea, U.S.A, Japan and Europe. By using this, the technique level of Korea, the International trend of technology and condition of cooperation research was estimated and the necessity of research and development performance about the machining center for the IT part processing were inquired.

• Steel and Composite Structures
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• v.29 no.2
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• pp.161-173
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• 2018

Point bending is often used for cambering and curving structural steel girders. An analytical solution, applicable in the elasto-plastic range only, that relates applied loads to the desired curve was recently developed for inducing horizontal curves using four-point bending. This solution does not account for initial residual stresses and geometric imperfections built-in hot-rolled sections. This paper presents results from a full-scale test on a hot-rolled steel section curved using four-point bending. In parallel, a numerical analysis, accounting for both initial geometric imperfections and initial residual stresses, was carried out. The models were validated against the experimental results and a good agreement for lateral offset and for strain in the elasto-plastic and post-plastic ranges was achieved. The results show that the effect of initial residual stresses on deformation and strain is minimal. Finally, residual stresses due to cold bending calculated from the numerical analysis were assessed and a revised stress value for the service load design of the curved girder is proposed.

• Journal of the Korean Society for Railway
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• v.9 no.4 s.35
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• pp.467-472
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• 2006

This paper deals with the applicability of long-gauge deformation fiber optic sensors (FOS) to prestressed concrete structures. A main motivation is the desire to monitor the deflection of the railway bridges without intervenes of the signal intensity fluctuations. A 25 m long, 1.8 m deep PSC girder was fabricated compositely with 22 cm thick reinforced concrete deck. Two pairs of 3 m long-gauge sensors are attached to the prestressed concrete girder with parallel topology. Using the relationship between curvature and vortical deflection and the quadratic regression of curvatures at the discrete point, it is possible to extrapolate the deflection curve of the girder. The estimated deflection based on the developed method is compared with the results using conventional strain gauges and LVDTS. It has been demonstrated that the proposed instrumentation technique is capable of estimating the vertical deflection and neutral axis position of the prestressed concrete girder up to weak nonlinear region.