• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.2
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• pp.28-33
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• 2007

This paper describes development of low cost precision machine that has a vacuum chuck. This study mainly aims to find out a cutting condition for maintaining optimum surface condition and to examine cutting characteristics of the precision machine that is equipped by diamond bites. The cutting materials is oxygen free copper. Several experiments were carried out to find out the main factors that affect the surface roughness such as principal axis RPM(rotation per minute), feeding speed, and cutting depth. As a result, we obtain The optimum cutting condition of the developed precision machine.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.5
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• pp.461-466
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• 2013

In this paper, main mechanism and measurement method of energy consumption for machine tools are investigated by experiment and simulation. To evaluate total energy consumption of the machine tools, standard test workpiece and measuring method and test procedures are suggested. And, improvement of energy consumption evaluation by the motion kinematics theory is used. In addition, to estimate energy consumption of machine tools in design process, mass distribution of the structure and 5 axis motions are investigated and simulated by numerical analysis.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.1 s.190
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• pp.47-56
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• 2007

Recently, demands on mechanical micro machining technology have been increased in manufacturing of micro-scale precision shapes and parts. The main purpose of this research is to verify the accuracy and cost efficiency of the mechanical micro machining. In order to measure the precision and feasibility of mechanical micro machining, various micro features were machined. Aluminum molds were machined by a 3-axis micro stage in order to fabricate microchips with $200{\mu}m$ wide channel for capillary electrophoresis, then the same geometry of microchip was made by injection molding. To evaluate the cost efficiency of various micro manufacturing processes, cost estimation for mechanical micro machining was conducted, and actual costs of microchips fabricated by mechanical micro machining, injection molding, and MEMS (Micro electro mechanical system) were compared.

• Animal Systematics, Evolution and Diversity
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• v.30 no.2
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• pp.95-102
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• 2014

The four species of the suborder Holaxonia, Anthogorgia japonica Studer, 1889 of family Acanthogorgiidae, Astrogorgia rubra (Thomson & Henderson, 1906), Euplexaura attenuata (Nutting, 1910), and E. erecta (Kukenthal, 1908) of family Plexauridae have been newly recorded in Korea. They were collected from intertidal and sublittoral zones in the western and southern coasts and Jeju-do Island of Korea by SCUBA diving and fishing nets from 1969 to 2010. This study approaches holaxonians by focusing on external and internal morphologies including size, form, and color of colonies, branches, polyps, coenenchyme, axis, and spicules. Anthogorgia japonica is characterized by its planar growth form, dichotomously branched form, non-retractile polyps, and Astrogorgia rubra by arrangement of calyxes being situated in lateral side at stems and alternately in all sides at branches. Euplexaura attenuata is sparsely and laterally branched colony, and has straight wand-like stems. Euplexaura erecta has branches which run parallel to the main stem.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.3
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• pp.370-378
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• 1999

KOMPSAT is a three-axis stabilized light weight satellite, and one of the main mission objectives of the KOMPSAT is to conduct scientific and technological analysis in the areas of high resolution imaging and ocean color imaging. This kind of mission requires the satellite to roll up to 45 degrees. Bang-bang control for this rolling maneuver may activate the flexible modes, and therefore cause satellite pointing performance degradation. To deal with this problem, the roll attitude control system, especially for the science mode and maneuver mode of the KOMPSAT, is first verified by numerical simulation. And the open-loop control law for roll maneuver is proposed by use of series expansion and optimization. The proposed control law is applied to KOMPSAT to see its effectiveness.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.3
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• pp.80-90
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• 1994

In this paper, a high-resolution algorithm for detecting the orientation and position of the SMD and an algorithm for compensating the position and skew angle of the PCB are proposed. The proposed algorithm for the first topic consists of two parts. Its first part is a preprocessing step. in which corner points of the SMD are detected and they are grouped. Then the coarse angle of the principal axis is obtained by line fitting. The second part is a main processing step, in which the fuzzy Hough transform over the limited range of angles is applied to the corner points to detect precisely the orientation of the SMD. The position of the SMD is determined by using its four corner points. The proposed algorithm for the second topic is the one which detects a rotation angle and translation parameters of the PCB using a template matching method. The computer simulation shows that the parametes obtained by proposed algorithms are more precise than those by the several conventional methods considered. The proposed algorithms can be applied to the fast and accurate automatic inspection systems.

• 한국전산유체공학회:학술대회논문집
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• 2004.03a
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• pp.35-41
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• 2004

A numerical investigation has been made for flows in an axisymmetric circular cylinder with a rotating cone located at the bottom of the container. The axisymmetric container is completely filled with a viscous fluid. Major parameter for the present research is the vertex angle of the cone, otherwise Reynolds number of fluid and aspect ratio of the vessel is fixed. Main interest is in vortex breakdown of meridional circulation by rotation of the cone with respect to the longitudinal axis of the cylinder. The method to this problem is numerically to integrate momentum and continuity equations on a generalized body fitted grid system. The pattern of vortex breakdown is quite different from that in a right circular cylinder with flat end wall disks. Flow visualization photographs of a preceeding work are compared with the present numerical results.

• Journal of Mechanical Science and Technology
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• v.14 no.11
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• pp.1244-1249
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• 2000

Burr and shape distortion are two main problems in micro-grooving. In this study, a simplified model is proposed based on large thrust force due to the tool edge radius. Experiments are conducted with a single crystal diamond tool on a 3-axis snaper-like machine varying the depth of cuts, and groove angles on brass, aluminum and OFHC. Experiments have shown that the thrust force becomes a dominant variable in burr generation compared to the principal force when the depth of cut is less than 2${\mu}m$. And fewer burrs develop on more brittle materials. Shape distortion is significant only when the groove angle is small and the depth of cut is larger than 30 ${\mu}m$.

• Korean Journal of Psychosomatic Medicine
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• v.4 no.1
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• pp.124-137
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• 1996

As the society becomes more industrialized and modernized, we have more chances to experience a serious traumatic event. Post-traumatic stress disorder (PTSD) has 3 major categories of symptoms such as memory disturbance, hyperarousal and avoidance or numbness. I reviewed the psychobiological evidences in 3 main categories of symptoms and the biological treatment after a brief review of the epidemiology, psychosocial etiology and diagnosis of PTSD. The memory disturbance of PTSD might be developed by the potentiation of the memory pathway mediated by norepinephrine. PTSD induces HPA axis abnormality, it might also develop hippocampal dysfunction, which might contribute to the memory disturbance. The kindling effect develops desensitization, which might develop reexperiencing of the traumatic events and hyperarousal state. Chronic aroused state of locus ceruleus with resultant chronic maladaptive state of norepinephrine system, might develop hyperarousal state. Social avoidance and physical numbing state in PTSD might be caused by serotnin or opiate system. Stress induced analgesia might be developed by opiate reliesed against the acute stress. The biologic research results would help the selective treatment of PTSD.

• Fisheries and Aquatic Sciences
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• v.14 no.2
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• pp.118-122
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• 2011

Polysiphonia senticulosa Harvey (Ceramiales: Rhodophyta) was recorded for the first time in Korea, and its vegetative and tetrasporangial morphologies are described. This species is characterized by the combined features of having a vegetative axial segment with 4 pericentral cells, a main axis without cortication, pseudodichotomous branching, branches with sharply pointed apical cells, flexuous branches hooked backward below, the presence of cicatrigenous branches, axillary endogenous stichidia, and the production of 1-3 tetrasporangia per stichidium. Based on this study, it is distinguished from Polysiphonia morrowii Harvey by its flexuous branches and the number of tetrasporangia produced per stichidium.