• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.5
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• pp.457-467
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• 2016

In this study, we investigate the dispersion behavior of debris and debris cloud generated by high-velocity impacts using the smoothed particle hydrodynamics (SPH) technique. The projectile and target plate were made of aluminum, and we confirm the validity of the SPH technique by comparing the measured major and minor axis lengths of the debris cloud in the reference with the predicted values obtained through the SPH analysis. We perform high-velocity impact and fracture analysis based on the verified SPH technique within the velocity ranges of 1.5~4 km/s, and we evaluate the dispersion behavior of debris induced by the impact in terms of its kinetic energy. The maximum dispersion radius of the debris on the witness plates located behind the target plate was increased with increasing impact velocity. We derive an empirical equation that is capable of predicting the dispersion radius, and we found that 95％ of the total kinetic energy of the debris was concentrated within 50％ of the maximum dispersion radius.

• Journal of Korea Multimedia Society
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• v.13 no.5
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• pp.780-791
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• 2010

This paper presents a semi-autonomous authoring method which can intuitively create 3D game/ animation contents for unexperienced users. In particular, this method considers their convenience to provide them with easier authoring environments. The 3D game/animation contents created by this method consist of several scene components connected to each other in a logical flow structure. Thus, it is possible to easily understand the overview of 3D content description for its production and manipulate these scene components for efficient management. Four different genres of game/animation contents have been developed by using an authoring tool based on this method. According to results of a survey intended for game developers who created game contents with the authoring tool, this method is shown to save contents development cost/time as well as raise the efficiency and convenience of whole process of contents creation to the expected level.

• Journal of radiological science and technology
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• v.40 no.3
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• pp.485-491
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• 2017

The purpose of this study was to develop a method to improve the job satisfaction of sonograpers by analyzing the factors affecting professional self-concept and job satisfaction. For data collection, total 141 sonographers working in Busan took part in the structured questionnaire survey. The collected data were analyzed by SPSS. For verification of the professional self-concept and job satisfaction, independent t-test and one way ANOVA were executed. When the statistical significance was verified, Sheffe was used for post hoc test. As a result, professional self-concept and job satisfaction were higher when got married, and also when a proper salary was paid according to work experience and professional qualification was acquired. In addition, the factors that have the greatest effect on the job satisfaction were analyzed as professional self concept. In conclusion, in order to improve the job satisfaction of sonographers, it is necessary not only to establish a professional qualification system for the job skill development but also to provide an appropriate compensation system according to work experience.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.3
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• pp.216-223
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• 2009

A transverse drag interaction coefficient of the equivalent resistance coefficient formula for square multi-piers higher than water depth and arranged with equal intervals was studied. From the assumption that the energy loss due to drag interaction according to transverse intervals of resistance bodies is essentially identical to the energy loss due to thick orifice according to porosities, the transverse drag interaction coefficient was derived by employing the orifice's energy loss coefficient. The equivalent resistance coefficient formula including the drag interaction coefficient was compared with the numerical experiments using FLOW-3D, the performance of which was verified by Kim et al.(2008) in the experimental condition with the multi-piers. The comparisons showed good agreement and thus, the equivalent resistance coefficient formula, which does not only consider frictional resistance but also consider the multi-piers' drag resistance varied according to the intervals in longitudinal or transverse direction, was verified.

• Journal of the Korea Society for Simulation
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• v.23 no.2
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• pp.65-72
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• 2014

Sensor nodes are easily compromised by attacker when which are divided in open environment. The attacker may inject false report and false vote attack through compromised sensor node. These attacks interrupt to transmission legitimate report or the energy of sensor node is exhausted. PVFS are proposed by Li and Wu for countermeasure in two attacks. The scheme use inefficiency to energy of sensor node as fixed report threshold and verification node. In this paper, our propose the next neighbor node selection scheme based on fuzzy logic system for energy improvement of PVFS. The parameter of fuzzy logic system are energy, hops, verification success count, CH select high the next neighbor node among neighbor nodes of two as deduction based on fuzzy logic system. In the experimental, our proposed scheme was improvement to energy of about 9% compare to PVFS.

• The Journal of the Korea Contents Association
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• v.8 no.9
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• pp.194-203
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• 2008

CIMT(Constraint Induced Movement Therapy) is to improve the function and use of damaged upper limbs by not only confinement of unaffected limbs' exercise but also inducement of affected limbs' one. The purpose of the study is to verify the effect of CIMT by means of motor behaviour test and immunohistochemistry, using animal models. This study was analyzed using 40 male Sprague-Dawley rats as the experimental groups and 40 ones as the control groups. The rats were divided into two random groups : one group as an experimental group which was operated on under anesthesia and removed somatomotor regions with CIMT and the other as the control group without CIMT.Postural Reflex Test, Beam Walking Test, Limb Placement Test and Immunohistochemistry were run on the day 1, 3 , 7 and day 14 following surgery to each 10 rat. As a result, this study demonstrates that CIMT might be an effect method to verify the plasticity of central nervous system as motor behaviour test made all high scores (p<.05) and BDNF was high too in experimental groups.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.35 no.2
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• pp.45-57
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• 2017

The royal tombs of the Joseon Dynasty are divided into the entrance space of the inner and outer spirits in accordance with the characteristic of the ritual act. In each space, the ritual facilities are arranged and managed according to the characteristics of ritual acts and space. In the case of the Joseon royal tombs listed in the World Heritage List in 2009, further conservation and management of the original form is required, and the need to restore the original form is required. Especially, Yungneung and Geolleung requires landscape management in accordance with the World Heritage site management regulations, for example, management of horizontal 60 degrees view. This study aims to propose a prototype verification, preservation and restoration plan for the landscape around the core area of the damaged source. Through the verification of the old literature and field investigation, conservation and restoration plan is proposed for the landscape of the ridge, the water system, the scenery around the ridge line, and the historical scenery.

• The Journal of the Convergence on Culture Technology
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• v.3 no.1
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• pp.9-18
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• 2017

The purpose of this study is to investigate the effects of smoking warning phrases on cigarette packages on students' attitudes toward smoking. Two research hypotheses were established to verify the effectiveness of the cigarette warning phrase. In order to verify the hypothesis, 129 students of Chung - Ang University were used. In order to investigate the difference of attitude toward smoking according to the presence or absence of smoking warnings, two types of questionnaires were prepared. Statistical program SPSS 18.0 was used and frequency analysis, t-test, ANOVA and multiple regression analysis were performed. The presence or absence of witnessing the smoking warnings were found to have a statistically significant effect on the smoking attitude score. Sex and parental smoking did not have any significant effect.

• The Journal of the Acoustical Society of Korea
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• v.30 no.2
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• pp.63-72
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• 2011

Since the detection probability is critically dependent on the target strength (TS) in active sonar and on the radiated noise level (RNL) in passive sonar, the acoustic materials for echo reduction (ER) and transmission loss (TL) are widely used for the stealth of underwater targets. In this paper, a measurement system based on the small water tank, for the frequency range of greater than 30 kHz, is developed and verified using reference targets. In order to design the water tank and the geometry of test samples, a program is developed to calculate the arrival time of interfering signals due to the reflection from water tank walls and also due to the diffraction from the edge of the test samples. Considering all the interfering signals, an optimal experimental configuration for water tank and test samples is designed and used throughout the experiment. Next, the signal processing algorithms to estimate ER and TL are developed based on the measured propagation loss reflecting the geometric spreading characteristics of the transducer. Finally, a set of reference targets such as aluminium plate and perfectly reflecting plate are used in a small water tank to verify the developed measurement system.

• Journal of the Korean Magnetics Society
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• v.27 no.2
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• pp.63-69
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• 2017

Naval ships are particularly required to maintain acoustic and magnetic silence due to their operational characteristics. Among them, underwater magnetic field signals derived by ships are likely to be detected by threats such as surveillance systems and mine systems at close distance. In order to increase the survivability of the vessels, various techniques for reducing the magnetic field signal are being studied and it is necessary to consider not only the magnitude of the magnetic field signal but also the gradient of it. In this paper, we use the commercial electromagnetic finite element analysis tool to predict the induced magnetic field signal of ship's scaled model, and arrange the degaussing coil. And the optimum degaussing current of the coil was derived by applying the particle swarm optimization algorithm considering the gradient constraint. The validity of the optimal degaussing technique is verified analytically by comparing the magnetic field signals after the degaussing with or without gradient constraint.