• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.2
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• pp.220-227
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• 1998

In substitution of beam-nonlinear spring model for real-car, it may have errors due to complicated characteristics of joint and overestimation of joints stiffness. In this research, a method for the joint modeling was suggested by nonlinear static and dynamic analyses of beam and shell joint models and verified by the application of accomplished joint modeling method to simplified full car model. In consequence, modified simplified full car model was improved in local acceleration and rigid wall force. Finally, the frontal crash analyses with the dummy were established and the accelerations of accelerations of head, chest and pelvis had good agreements with those of shell model.

• Tribology and Lubricants
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• v.29 no.1
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• pp.7-12
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• 2013

Turbine power control devices at a nuclear / thermoelectric power plant lead to failure by creating mechanical shocks and strong vibrations that are due to the strong elasticity of a spring and the inertia of the valve face during its rapid movement to block steam. To ensure durability of the turbine power control device, which is the main component in the power plant, it is necessary to develop a device that can prevent such vibrations. In this study, a cushion mechanism is added to the head of the hydraulic servo actuator, which is a turbine power control device. Moreover, the cushion mechanism, which includes various modifies shapes and orifices is investigated dynamically through modeling and simulations.

• Korean Journal of Childcare and Education
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• v.14 no.3
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• pp.97-115
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• 2018

Objective: This study aimed to analyse the influence of young children's playfulness at home and class characteristics on their playfulness at kindergarten. Methods: Twenty eight classes of 3, 4 and 5 year olds in Gyeonggi and Chungbuk provinces were recruited. Participants of this study were mothers and head teachers of the children of recruited classes. Analyses was implemented using hierarchical linear modeling with HLM 7.0. Results: Differences were found in children's playfulness at kindergarten according to their classes. Individual characteristics including, gender, age and playfulness at home were shown to have significant influences on playfulness at kindergarten, while relevance of variable class characteristics to playfulness at kindergarten was not observed. Conclusion/Implications: It is concluded that playfulness of children is more related to playfulness at home rather than class characteristics, implying the strong characteristic of playfulness as an individual trait.

• Journal of International Society for Simulation Surgery
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• v.2 no.1
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• pp.7-9
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• 2015

Purpose In the many face-related application such as head pose estimation, 3D face modeling, facial appearance manipulation, the robust and fast facial feature extraction is necessary. We present the facial feature extraction method based on shape regression and feature selection for real-time facial feature extraction. Materials and Methods The facial features are initialized by statistical shape model and then the shape of facial features are deformed iteratively according to the texture pattern which is selected on the feature pool. Results We obtain fast and robust facial feature extraction result with error less than 4% and processing time less than 12 ms. The alignment error is measured by average of ratio of pixel difference to inter-ocular distance. Conclusion The accuracy and processing time of the method is enough to apply facial feature based application and can be used on the face beautification or 3D face modeling.

• Applied Science and Convergence Technology
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• v.23 no.3
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• pp.139-144
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• 2014

GaN deposition equipment and processes for the fabrication of white LEDs (Light Emitting Diode) using MOCVD (Metal Organic Chemical Vapor Deposition) were numerically modeled to analyze the effects of a reactive gas introduction strategy. The source gases, TMGa and $NH_3$, were injected from a shower head at the top of the chamber; the carrier gases, $H_2$ or $N_2$, were introduced using two types of injection structures: vertical and horizontal. Wafers sat on the holder at a radial distance between 100 mm and 150 mm. The non-uniformity of the deposition rates for vertical and horizontal injection were 4.3% and 3.1%, respectively. In the case of using $H_2$ as a carrier gas instead of $N_2$, the uniform deposition zone was increased by 20%.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_1
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• pp.941-952
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• 2022

In this study, additive manufacturing technology was applied to restore a planner miller that was unusable due to aging. The drive spur gear of the planner miller was inoperable due to many defects in the teeth. The shape of the defective gear teeth was restored by deposition of the defective teeth using the DED method. However, as the location of the deposition head and the location of the set origin became farther, the deposition shape was different from the modeling shape. Nonetheless, since the modeling of the deposition part was designed to be larger than the tooth shape of the original gear, it was possible to completely restore all gear teeth through post-processing. The arrangement interval of the flow lines of the deposition part was narrower than that of the substrate. The hardness of the substrate was 172 HV, and that of the deposition part was 345 HV, which was twice as high as that of the substrate.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.807-810
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• 2000

입체음향 시스템에서 모노음에 방향감을 제어하기 위한 방법으로 FIR 필터 형태의 머리전달함수( HRTF : Head-Related Transfer Function)를 사용한다. 그러나 이때 사용되는 FIR형태의 머리전달함수는 높은 차수를 가지고 있어 실시간 음상정위 처리가 어려운 문제점을 가지고 있다. 본 논문에서는 FIR 형태의 머리전달함수를 ARMA 시스템 인지기법을 이용하여 저차의 IIR필터 형태로 모델링하여 실시간 데이터 처리가 가능하도록 하였다. 본 논문에서 제안하는 ARMA 시스템 인지기법을 이용하게 되면 주어진 고차의 FIR형태의 머리전달함수를 다양한 안정성을 갖는 IIR모델들을 얻을 수 있으며, 이들 중 적절한 스펙트럼오차를 갖는 저차의 IIR모델을 선택 할 수 있다.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06e
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• pp.35-38
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• 1998

입체음향 시스템의 방향감 제어에서 필수적인 머리전달함수(Head-Related Transfer Function)는 일반적으로 FIR 또는 IIR 필터로 구현되며, IIR 필터의 경우 FIR 보다 비교적 저차 모델링이 가능한 장점을 갖는다. 본 논문에서는 Balanced Model Reduction(BMR) 방법을 이용하여 비교적 높은 차수를 가지는 FIR 형태의 HRTF 필터를 IIR 필터로 설계하고, 입체음향 시스템의 실시간 구현시 필수적인 계산의 효율을 높이는 방법을 제시한다. 또한 IIR 필터로 근사화된 HRTF 필터의 주파수 패턴을 분석하여, 음상정위에 큰 영향을 미치는 주파수 대역을 좀 더 나은 해상도를 갖도록 설계하여 저차 모델 설계시 발생하는 오차가 음상정위에 미치는 영향을 최소화 하였다.

• Proceedings of the SAREK Conference
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• 2003.07a
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• pp.246-246
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• 2003

• Journal of the Korean Geotechnical Society
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• v.24 no.7
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• pp.61-73
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• 2008

Piles of a bridge pier are connected with the column through the pile cap (footing). Behavior of the pile foundation can be different according to the connection method between piles and the pile cap. Connection methods between pile heads and the pile cap are divided into two groups : rigid connections and hinge connections. Domestic design code has been specified to use rigid connection method for the highway bridge. In the rigid connection method, maximum bending moment of a pile occurs at the pile head and this helps the pile to prevent the excessive displacement. Rigid methods are also good to improve the seismic performance. However, some specifications prescribe that conservative results through investigations of both the fixed-head condition and the free-head condition should be reflected in the design. This statement may induce an over-estimated design for the bridge which has high-quality structures with casing covered drilled shafts and the PC-house contained pile cap. Because the assumption of free-head conditions (hinge connections) is unreal for the elevated pile cap system with multiple piles of the long span sea-crossing bridges. On the other hand, elastic displacement method to evaluate the pile reactions under the pile cap is not suitable for this type of bridges due to impractical assumptions. So, full modeling techniques which analyze the superstructure and the substructure simultaneously should be performed. Loads and stress state of the large diameter drilled shaft and the pile cap for Incheon Bridge which will be the longest bridge of Korea were investigated through the full modeling for rigid connection conditions.