• Journal of the Society of Naval Architects of Korea
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• v.50 no.3
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• pp.175-181
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• 2013

This paper presents a simulation for passenger ship evacuation considering the inclination of a ship. In order to describe a passenger's behavior in an evacuation situation, a passenger is modeled as a rigid body which translates in the horizontal plane and rotates along the vertical axis. The position and rotation angle of a passenger are calculated by solving the dynamic equations of motions at each time step. To calculate inclined angle of damaged ship, static equilibrium equations of damaged ship are derived using "added weight method". Using these equations, physical external forces due to the inclination of a ship act on the body of each passenger. The crowd behavior of the passenger is considered as the flock behavior, a form of collective behavior of a large number of interacting passengers with a common group objective. Passengers can also avoid an obstacle due to penalty forces acting on their body. With the passenger model and forces acting on its body, the test problems in International Maritime Organization, Maritime Safety Committee/Circulation 1238(IMO MSC/Circ.1238) are implemented and the effects of ship's inclination on the evacuation time are confirmed.

• Journal of the Korean Magnetics Society
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• v.6 no.4
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• pp.235-241
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• 1996

Co/Pd and Co/Pt multilayered thin films for perpendicular magnetic recording media were fabricated by sput¬tering method and the effects of the sputtering pressure during the formation of Pd or Pt underlayers on the magnetization behavior and coercivity of the multilayers were investigated. It was found that the coercivity of Co/Pd multilayers was strongly dependent on the sputtering pressure of underlayer and could be enhanced to a large extent merely by increasing the sputtering pressure of underlayer, while in case of Co/Pt films, the degree of coercivity enhancement by controlling the sputtering pressure of underlayer was almost negligible. Coercivity variation of Co/Pd and Co/Pt multilayers with the underlayer material and deposition pressure of underlayer could be well explained in terms of the interface roughness of multilayer films induced by underlayer topology, which could also be correlated to the change of perpendicular anisotropy energy and magnetic reversal feature with the sputtering pressure of underlayer. Kerr rotation angle was hardly affected by the preparation conditions of underlayers.

• Archives of Plastic Surgery
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• v.39 no.6
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• pp.626-630
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• 2012

Background Recent literature has indicated that free flaps are currently considered the preferred choice for head and neck reconstruction. However, head and neck cancer patients are frequently treated with chemoradiotherapy, which is often associated with a poor general and local condition, and thus, such patients are ineligible for free flap reconstruction. Therefore, other reconstruction modalities should be considered. Methods We used lower trapezius musculocutaneous (LTMC) flap based on the dorsal scapular artery to reconstruct head and neck defects that arose from head and neck cancer in 8 patients. All of the patients had undergone preoperative chemoradiotherapy. Results There were no complications except one case of partial flap necrosis; it was treated with secondary intention. Healing in the remaining patients was uneventful without hematoma, seroma, or infection. The donor sites were closed primarily. Conclusions The LTMC flap is the preferred flap for a simple, reliable, large flap with a wide arc of rotation and minor donor-site morbidity. The authors recommend this versatile island flap as an alternative to microvascular free tissue transfer for the reconstruction of defects in the head and neck region, for patients that have undergone preoperative chemoradiotherapy.

• Journal of the Korean Society of Costume
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• v.57 no.4 s.113
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• pp.9-17
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• 2007

Somatotype is human body shape and physique type which can be classified not only by the size, but also by the shape or posture of the body. Postural variations in the alignment of the back, shoulder, and neck can have an adverse effect on the fit of garments designed to hang from the shoulders. There have been some previous studies about the lateral upper torso by analyzing photographic measurements. In this study, 3D body scan images were used to classify the side somatotype of upper lateral method even though they are major data in the classification of upper torso. This study focused on following objective.; 1) To apply new and developing technology into the apparel industry analyzing 3D body scan images. 2) To classify upper laterla torso using the data through the new improver technology, 3D body scanner. 3) To propose basic materials for well fitted garments for each type of figure. The test subjects for this study were two hundreds nine female aged 19 years and up who were recruited in Cornell university body scan research team. Seventeen Variables(12 angles, 5 lengths) out of 3D body scan data were measured based on these landmarks and applied to analyze. The result of factor analysis indicated that 6 factors were extracted through factor analysis and orthogonal rotation by the method of Varimax and those factors comprise 62.5% of total variance. And the somatotype of upper body is classified into 3 types of figures according to cluster analysis; Bent forward posture, Straight posture, Swayback posture. Future study could be addressed about the somatotype of body by the age group based on the large database with wide variety of age.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.12
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• pp.15-21
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• 2019

The worm reducer is capable of quadrature power transmission when the shafts are disposed at right angles to each other. Since a large reduction ratio can be obtained of up to approximately 1/100 and a sliding movement is performed during operation compared with other gears, the noise and vibration are small, and there is the advantage that reverse rotation can be prevented. On the other hand, severe wear and damage are displayed on the gear and worm tooth surface, and many defects, such as intense heat generation of the reducer, occur. In the reducer case, the four-piece casing method was selected to solve the problems of heat generation, transmission efficiency, and assemblability. In this paper, we analyzed the problems of the worm and worm wheel (the core parts of a 5-Ton worm reducer) and casing through these methods and researched how to solve them.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.5
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• pp.399-406
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• 2016

The large scale wind turbine blades usually experience periodic change of inflow speed due to blade rotation inside the ground shear flow region. Because of the vertical wind shear, the inflow velocity in the boundary layer region is maximum at uppermost position and minimum at lowermost position. These spatial distribution of wind speeds can lead to the periodic oscillation of the 6-component loads at hub and low speed shaft of the wind turbine rotor. In this study we compare the aerodynamic loads between two inflow conditions, i.e, uniform flow (no vertical wind shear effect) and normal wind profile. From the computed results all of the relative errors for oscillating amplitudes increased due to the ground shear flow effect. Especially bending moment and thrust at hub, and bending moments at LSS increased enormously. It turns out that the aerodynamic analysis including the ground shear flow effect must be considered for fatigue analysis.

• Korean Journal of Organic Agriculture
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• v.15 no.4
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• pp.399-411
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• 2007

Korean organic farming has been well developed over the last two decades. It demonstrates that the number of certificated farm for organic agriculture and products have been drastically increased in recent year. However, the organic farmers have thought that organic farming rely only on organic fertilizer and they don't keep organic farming principle in which organic farmer should enhance biological activity and crop rotation. This study was to compare nutrient input, recommendation, cropping system and organic product circulation between the early $20^{th}$ century and beginning of the $21^{st}$ century. The population of Korea has increased 7.3 times more than that of a century ago but cultivated land has been decreased during 100 years. The rice production in 2002 was 4.2 times higher than that of production in 1912. The input of N, P and K in 1907 on the basis of King's suggestion was 95.6kg/ha, 15.9kg/ha and 3.0kg/ha, respectively. Nitrogen came from excreta (40%), green manure (55%) and compost (5%) in the early 20th century. On the other hand, organic farmer input organic resources such as wood chip (30.1%), compost (27.8%), rice straw (14%) and others (25%) these days. In terms of nutrient balance calculated nutrient and absorption by plants, organic rice farmer apply excessive nitrogen and phosphorus to the soil. They was used to put $7{\sim}10$ times more nitrogen than that of a century ago. Nutrient recommendation was similar in N and P between early 20th century and early $21^{st}$ century. Farmers in both century did not rotate crops in the field. Today, organic farmers engaged in more continuous cultivation than in early 20th century. Farmers in the early $20^{th}$ century produced locally, consumed locally the agricultural products, but organic farmers in the $21^{st}$ century produce the organic product in the local farmland and consumed in the large city and also a lot of foreign organic products have been imported in recent year.

• Journal of the Korean Society of Radiology
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• v.5 no.3
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• pp.121-125
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• 2011

This study was intended to evaluate the surface dose and depth dose of according to the distance of the treatment room wall. High energy photon beams from linear accelerators produce large scattered radiation by various components of the treatment head, collimator and walls or objects in the treatment room including the patient. The scattered radiation measured by thermoluminescence dosimeter(TLD). Linear accelerators rotation center of the four walls(X) distance was measured to be 236, 272, 303, and 337 cm. The result of 100 cGy and 200 cGy of 6 MV photon irradiation, surface dose was 0.49, 0.83 mSv at 236 cm of the shortest distance to the wall, In 272 cm 0.41, 0.53 mSv, 303 cm in the 0.28, 0.57 mSv, and 337 cm distance from the wall in the 0.33, 0.76 mSv surface dose respectively. There was remarkable difference in the surface dose among the treatment room wall distance. The results of useful data in relation to stochastic effect for radiation therapy patients.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1211-1222
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• 2011

It is necessary to use prestressed modal analysis to calculate the modal frequencies and mode shapes of a prestressed structure such as a spinning blade, a preloaded structure, or a thermally deformed pipe, because the prestress effect sometimes causes significant changes in the frequencies and mode shapes. When the finite element model under consideration has a very large number of degrees of freedom, repeated prestressed modal analyses for investigating the prestress effects might become too computationally expensive to finish within a reasonable design-process time. To alleviate these computational difficulties, a Krylov subspace-based model order reduction, which reduces the number of degrees of freedom of the original finite element model and speeds up the necessary prestressed modal analysis with the reduced order models (ROMs), is presented. The numerical process for the moment-matching model reduction is performed directly on the full order models (FOMs) (modeled in ANSYS) by the Arnoldi process. To demonstrate the advantages of this approach for performing prestressed modal analysis, the prestressed wheel and the compressor impeller under their high-speed rotation are considered as examples.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.309-313
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• 2006

Many researchers have studied on the lightness of automobile. These researches are such as a body shell, sub frame, fuel tank, engine etc. The transmission Part is a magnitude one in the aspect of weight. A drive shaft (propeller shaft) transmits the engine power to rear differential gear assembly. It is used in the compact car that is a single drive shaft. But in the case of long body cars such as SUV (Sports Utility Vehicle), truck and large vehicle, two or three divided drive shaft are used to prevent the vibration damage from a drive shaft that has been taken high torsion and rotation. This multi-divided drive shaft structure is so heavy because it is assembled by yoke, center bearing and solid spline axis. When the rear axle move up and down, the spline shaft adjust the variation of a length between the transmission and rear axle gearbox. In this paper, it is studied in the experimental method that is a bending vibration characteristic of slip in tube shaped propeller shaft. This type propeller shaft is developed to combine the spline axis with drive shaft and can be light in weight of transmission part.