• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.55-60
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• 2006

It is well known tint the ship manoeuvring motion is greatly affected by hydrodynamic forces and moments acting between two vessels passing too close to each other in confined waters, such as in a harbour or narrow channel. This interaction between two vessels could be assumed to be the functions of the longitudinal distance, transverse distance and their speeds. The aim of this study is to calculate the interaction between two vessels passing close to each other on parallel courses by simulation, and to estimate the effect of rudder action and time of collision through simulation under the condition of various longitudinal distances and different speed-ratios of the two vessels.

• 한국해양학회지
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• v.27 no.3
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• pp.197-209
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• 1992

The distribution pattern of macrobenthic polychaete worms and their feeding guild structures were investigated along the coastal region off Kunsan (southeastern Yellow Sea) during the winter season. The polychaete worms, the most dominant infauna, comprised 54 species in 30 families and showed their mean density of 300. indir./m$^2$). Dominant species in the study area were Stermaspis scutata, Lumbrineris cruzensis, Notomastus sp., Nephtys polybranchia, Praxillella affinis. Polychaeres were assigned to 12 feeding guilds and BMX (burrowing, motile, muscular pharynx) was the most dominant feeding guild (26%). Muddy sediments sustained more polychaete worms which showed burrowing (65%), motile (72%), and non-tentaculate strategies (92%), while sandy sediments contained more filter feeders (32%) and sessile (63%), and more tentaculate worms (49%). The sediment grain size was suggested to be the prime factor selecting the polychaete feeding guild.

• Journal of the Korean Applied Science and Technology
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• v.38 no.3
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• pp.762-770
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• 2021

The purpose of this study was to analyze the effect on the vertical ground reaction force, the elapsed time, and the center of pressure factors during gait by maepsi exercise program, which is a whole body exercise, to middle-aged women for 8 weeks. A total of 25 subjects participated in this study, 13 in the exercise group(age, 41±4.4 years; heigh, 162.5±5.8cm; weight, 57.8±6.7kg; body mass, 21.9±2.4kg/m2) and 12 in the control group(age, 41.1±5.6 years; height, 160.9±5.5 cm; weight, 576.2±8.1 kg; body mass, 21.7±2.9 kg/m2). In the exercise group, the maepsi exercise program consisting of 7 areas, 23 types and 77 movements, was conducted 3 times a week for 8 weeks. Two-way repeated measures ANOVA was performed to verify the ground reaction force factors during gait, and the post-test was analyzed with bonferroni adjustment(a=.05). In the exercise group, compared to the control group, the exercise group showed higher values than the control group in the elapsed time to FMWA and FPO, vertical ground reaction force at FMWA and FPO, and RMS factors of COP in the AP direction. Therefore, it was found that the 8-week maepsi exercise program improved the acceleration and deceleration exercise functions of middle-aged women who performed gait.

• The korean journal of orthodontics
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• v.35 no.2 s.109
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• pp.116-126
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• 2005

The object of this study was to evaluate how friction that occurs during the sliding movement of an orthodontic archwire through orthodontic brackets is differently affected by variant designs and ingredients of brackets and archwires and bracket-archwire angles. In order to simulate the situations which could occur during orthodontic treatment with fixed appliances, 4 types of brackets (Gemini, a stainless steel twin bracket, Mini Uni-Twiu. a stainless steel bracket with a single bracket design and narrow mesio-distal width; Clarity, a metal-reinforced ceramic bracket; Transcend, a ceramic bracket) and 3 types of orthodontic archwires $(0.016',\; 0.016{\times}0.022'\;stainless\;steel,\;0.016'\;Nitinol)$ were used and the bracket-archwire angles were controlled as $0^{\circ},\;3^{\circ}\;6^{\circ},\;and\;9^{\circ}$ Gemini significantly show and the lowest static and kinetic frictions (P<0.001) Clarity showed the highest static and kinetic frictions with a bracket-archwire angle of $0^{\circ}$. and Transcend at $6^{\circ}\;and\;9^{\circ}$ (P<0.001). An $0.016{\times}0.022'$ stainless steel rectangular archwire significantly showed the highest static and kinetic frictions (P<0.01). The lowest static and kinetic frictions were observed when the bracket-archwire angles were $0^{\circ}\;and\;3^{\circ}$ with 0.010' stainless steel round archwires (P<0.01), and $6^{\circ}\;and\;9^{\circ}$ with 0.016 Nitinol (P<0.001). The static and kinetic frictions were increased as the bracket-archwire angles were increased (P<0.001)

• Journal of Chest Surgery
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• v.29 no.3
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• pp.311-314
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• 1996

Eighteen patients (13 female and ave male) aged from 15 to 62 years (mean age 42.6 years) underwent excision of cardiac myxoma(17 left atrial, one right atrial) between 1985 and 1994 at Pusan National University hospital. All patients complained of exertional dyspnea and most had a few additional symtoms including palpitation, chest pain, syncope, general weakness, weight loss, fever, cough and epigastric disconyort. The diagnosis was made by echocardiography alone in left atrial myxomas but a myxoma in right atrium was diagnosed incidentally during mitral valve replacement for rheumatic valvular heart disease. The tumor attachment sites were fossa ovalis in 13, other interatrial septum in 4, mitral valve annulus in one and free wall of left atrium in two cases. The tumor was excised successfully via right atriotomy in 8 and biatriotomy in 10 cases. There was no hospital nor late death, and no recurrent case during the follow up period. Curative surgical excision of cardiac myxoma can be performed with low morbidity and very low r currence rate.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.4
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• pp.27-34
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• 2005

The paper discussed on the stability of cantilevered pipe conveying fluid subjected to distributed follower force. Governing equations of motion are derived by extended Hamilton's principle, and the numerical scheme using finite element method is applied to obtain the discretized equations. The critical flow velocity as a function of the distributed follower force for the various mass ratio is determined. The flutter configurations of the pipes at the critical flow velocities are drawn graphically at every twelfth period to define the order of quasi-mode of flutter configuration The critical mass ratios, at which the transference of the eigenvalue branches related to flutter take place, are definitely determined. Also, the effect of damping on the stability of the system is considered.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.1
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• pp.42-54
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• 2009

Contrast to the 6-DOF nonlinear dynamic modeling of nonlinear tracking problem, 3-DOF point-mass modeling of flight mechanics is efficient and adequate for applying the trajectory optimization problem. There exist limitations to apply an optimal trajectory from point-mass modeling as a reference trajectory directly to conduct the nonlinear tracking control, In this paper, new matching trajectory optimization scheme is proposed to compensate those differences of mismatching. To verify performance of proposed method, full ascent three-dimensional flight trajectories are obtained by reflecting the real constraints of flight conditions and airship performance with and without jet stream condition. Then, they are compared with the optimal trajectories obtained from conventional method.

• Journal of Korean Orthopaedic Sports Medicine
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• v.10 no.2
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• pp.109-112
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• 2011

Anatomical reduction and strong fixation in displaced patella fracture are needed for restoration of knee function and strength and early range of motion exercise. According to the type of fracture and various operational methods, their many complications have been reported. We report 2 cases of transverse patella fracture which were caused by transverse screw fixation in longitudinal patella fracture and fracture of bipartite patella in athletes.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.3
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• pp.275-284
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• 2011

The accuracy simulation technology of linear motion system is introduced in this paper. Motion errors and positioning errors are simulated using informations on the design parameters of elements of linear motion system. 5 Degree-of-freedom motion error analysis algorithm utilizing the transfer function method and positioning error analysis algorithm which are main frame of accuracy simulation are introduced. Simulated motion errors are compared with experimental results for verifying the effectiveness. Then, using the proposed algorithms, simulation is performed to investigate the effects of ballscrew and linear motor on the motion errors. Finally, the influence of feedback sensor position on the positioning error is also discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.671-677
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• 1996

This paper proposes a study on the effects of motion errors for acceleration/ deceleration types. The proposed motion errors are consisted of two errors : one due to transient response of servomechanism and the other due to gain mismatching of positioning servo motor. They are derived from using laplace transformation for the block diagram of general purpose feed drive system. In order to minimize them, the paper proposes second order polynomial regression model by using orthogonal array method which describes one of experimental methodolgies. The validity and reliability of the study was veri lied on a vertical machining center equipped with FANUC 0MC through a series of experiments and analyses.