• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.118-121
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• 2004

Manufacturing process for milli components has recently gained researcher's focus with the increasing tendency toward highly integrated and micro-scaled parts for electronic devices. The milli-components cannot be formed by the conventional manufacturing process since the parts require higher dimensional accuracy than the conventional ones. In order to enhance the forming accuracy and productivity, various forming procedures proposed and studied by many researchers. In this paper, forming analysis of milli-components has been studied with a new micro-former. In modeling of progressive dies, multi-stage forming sequence has been analyzed with finite element analysis by LS-DYNA3D. The analysis proposes the sequential die and part shapes with the corresponding punch force and dimensional accuracy. The analysis also considers the effect of elastic dies on the dimensional accuracy of the formed parts. The analysis result demonstrates that the elastic analysis in the milli-forming process is indispensable fur accurate forming analysis. The analysis procedure in the paper will provide good information in design of a new micro-former and milli-component.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.105-105
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• 2010

Voltage circuit breakers are widely used in power distribution systems to interrupt fault current rapidly and to assure the reliability of the power supply. Power distribution system requires the transformer with higher capacity than ever, but this ever, but this may be the cause. of the increasing of short circuit current in contrast to conventional one when short-circuit accident is occurred. Therefore molded case circuit breaker improved in aspects of interrupting capacity of short circuit current in this system is needed. By using the proposed methods in this paper, such as new arc quenching structure of grid would contribute to minimizing the MCCB, realization of high interrupting performance and reducing the design time and development cost.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.269-274
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• 2001

This research covers the development of new technique for composite injection molding of high stiffness Sabot. An analysis of polymer resin is performed by means of making test specimen mold and doing test with accordance of ASTM test guidelines. Structural analysis and simulation of injection molding process are carried out in order not only to estimate but also to predict the characteristics of molding stresses what both product and structure of mold may have. For structural analysis software, Moldflow and LS-dyna are used and universal test machine is utilized for evaluating performance of sabot. Cases of adopting this material to sabot are not announced yet in domestic academic world. In addition to that, materials for polymer-metal mixed injection molding are imported on the whole due to deficient level of domestic technology. Therefore, this new developed injection molding technique using PEI material can make it available to ensure the technology of making mold, injection and design. Finally, this technique may be applicable to another sabot having different radius of warheads from now on.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1129-1137
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• 2007

50kg NSI PCT(Prestress Concrete Timber, sleeper) is developed for the purpose of low maintenance cost, Extend life cycle, Track stability, Friendly Environment, Good running quality. In this study, as a part of research which is to make renovated NSI turnout, the main objective of this study is the optimization of PC sleeper's section, the number of PS tension wire. For this purpose, the finite element analysis was conducted to evaluate the serviceability and the safety of NSI PC sleeper developed.

• Steel and Composite Structures
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• v.23 no.2
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• pp.153-160
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• 2017

It is extremely important to be aware of the ballistic performances of engineering materials in order to be able to choose the lightest armor providing full ballistic protection in civil and military applications. Therefore, ballistic tests are an important part of armor design process. In this study, ballistic performance of plates made of carbon steel and cold worked tool steel against 7.62 mm AP (armor-piercing) bullets was examined experimentally and numerically in accordance with NIJ standards. Samples in different sizes were prepared to demonstrate the effect of target thickness on ballistic performance. Some of these samples were coated with titanium nitride using physical vapor deposition (PVD) method. After examining all successful and unsuccessful samples at macro and micro levels, factors affecting ballistic performance were determined. Explicit non-linear analyses were made using Ls-Dyna software in order to confirm physical ballistic test results. It was observed that the ballistic features of steel plates used in simulations comply with actual physical test results.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.3
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• pp.200-207
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• 2001

In this paper, we propose an HMM(Hidden Markov modeJ)-MLP(Multi-layer perceptron) hybrid model for recognizing legal words on the English bank check. We adopt an explicit segmentation-based word level architecture to implement an HMM engine with nonscaled and non-normalized symbol vectors. We also introduce an MLP for implicit segmentation-based word recognition. The final recognition model consists of a hybrid combination of the HMM and MLP with a new hybrid probability measure. The main contributions of this model are a novel design of the segmentation-based variable length HMMs and an efficient method of combining two heterogeneous recognition engines. ExperimenLs have been conducted using the legal word database of CENPARMI with encouraging results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.12
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• pp.971-976
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• 2006

The objectives of this paper are to study the characteristics of pool boiling heat transfer for enhanced tubes used in the evaporator of turbo chiller and to provide a guideline for optimum design of an evaporator using HFC134a. Three different enhanced tubes are tested at 4 different saturation temperatures. The wall super heated temperature difference ranges from $0.5^{\circ}C\;to\;3.5^{\circ}C$. The refrigerant, HFC134a evaporates on the outside of the tube while the chilled water flows inside the tube. This study provides experimental heat transfer coefficients for evaporation on the enhanced tubes. It is found that the turbo-II tube provides the highest heat transfer coefficient.

• Research in Community and Public Health Nursing
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• v.20 no.1
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• pp.12-22
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• 2009

Purpose: This study was done to investigate factors associated with depression and quality of life (QoL) among the community-dwelling elderly. Methods: This study used a descriptive correlational research design. The subjects were 730 elders aged over 65 living in D district of Daegu. Data were collected using questionnaires for 30 days in April, 2007. The research instruments utilized in this study were a physical function scale of long-term care insurance system, Geriatric Depression Scale Short Form Korea Version (GDSSF-K), and Korean Quality of Life Scale (KoQoLs). The collected data were analyzed by descriptive statistics, t-test, ANOVA, Duncan, stepwise multiple regression, and Spearman correlation. Results: The mean age of the subjects was 72.6, and 68.8% and 57.9% of subjects were, respectively, female and living alone. 12.3% of variance in depression was explained by age, education, economic status, subjective health, alcohol consumption, condition of teeth, and fall experience. 18.2% of variance in QoL was explained by economic status, number of diseases, condition of teeth, incontinence, paralysis, and IADL. Economic status and condition of teeth were contributing factors to depression and QoL of the elderly. Conclusion: Findings of this study may be useful in understanding the health status of the community-dwelling elderly and developing more regionally specific health promotion strategies.

• Geomechanics and Engineering
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• v.9 no.1
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• pp.39-55
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• 2015

Usually the analyses of structures are carried out by assuming the base of structures to be fixed. However, the soil beneath foundation alters the earthquake loading and varies the response of structure. Hence, it is not realistic to analyze structures by considering it to be fixed. The importance of soil-structure interaction was realized from the past failures of massive structures by neglecting the effect of soil in seismic analysis. The analysis of massive structures requires soil flexibility to be considered to avoid failure and ensure safety. Present study, considers the seismic behavior of multi-storey reinforced concrete narrow and wide buildings of various heights with and without shear wall supported on raft foundation incorporating the effect of soil flexibility. Analysis of the three dimensional models of six different shear wall positions founded on four different soils has been carried out using finite element software LS DYNA. The study investigates the differences in spectral acceleration coefficient (Sa/g), base shear and storey shear obtained following the seismic provisions of Indian standard code IS: 1893 (2002) (IS) and International building code IBC: 2012 (IBC). The base shear values obtained as per IBC provisions are higher than IS values.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.91-98
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• 2004

This paper is concerned with crash analysis for an auto-body member with the forming effect. Auto-body members such as a front frame assembly are fabricated with sheet metal forming processes that induce forming histories such as the plastic work hardening and non-uniform thickness distribution. Numerical simulation is carried out with LS-DYNA3D in order to identify the forming effect on the crashworthiness. The crash analysis of the front frame assembly with the forming effect leads to a different result from that without the forming effect. Crashworthiness such as the load-carrying capacity, the crash mode and the energy absorption are calculated to investigate and identify the forming effect. It is fully demonstrated that the design of auto-body members needs to consider the forming effect for accurate assessment of the load-carrying capacity and the deformation mechanism of the formed members.