• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.5
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• pp.235-241
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• 2018

The internal pressure is a critical parameter for designing a pressure vessel. The static pressure that a pressure vessel must withstand is usually determined according to the various codes and standards with simple formula or numerical simulations considering the geometric parameters such as diameter and thickness of a vessel. However, there is no specific codes or technical standards we can use practically for designing of pressure vessels which have to endure the detonation pressure. Detonation pressure is a kind of dynamic pressure which causes an impulsive pressure on the vessel wall in a extremely short time duration. In addition, it is known that the magnitude of reflected pressure at the vessel wall due to the explosion can be over twice the incident pressure. Therefore, if we only consider the reflected pressure, the design of the pressure vessel can be too conservative from the economical point of view. In this study, we suggest a practical method to evaluate the magnitude of maximum allowable pressure that the pressure vessel can withstand against the detonation inside a vessel. As an example to validate the proposed method, we consider the pressure vessel containing hydrogen gas.

• Journal of Digital Contents Society
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• v.18 no.8
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• pp.1543-1550
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• 2017

Previous research on smartphone has been focused on personal performance, accessibility, and information gaps in information system quality. In order to analyze the relationship between the use of smartphone information and personal characteristics, this study conducted a survey of 300 tourists at Jeju Airport, by using three variables of self-efficacy, 'impulsiveness and demographic variables (age, sex, education level, etc.) of smartphone use with personal characteristics. In conclusion, self-efficacy and impulsiveness seem to be positively related to the use of smartphone because it seems to be a living environment in which the desired information can be acquired within a desired time. In addition, there seems to be a difference between a mobile native environment in which online and offline boundaries are always connected and an environment in which 40 to 50 digital literacies are connected. This can be interpreted as a result of additional analysis.

• Korean Journal of Biological Psychiatry
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• v.17 no.2
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• pp.70-78
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• 2010

Objectives : This study investigated the differences of working memory among the subtypes of ADHD. Methods : Eighty-one children and adolescents with ADHD and thirty normal controls were recruited. Children with any cognitive disorders and low intelligence were excluded. In order to evaluate the verbal and visuospatial working memory, Digit span and Finger windows tasks were measured, respectively. Performances on these measures between children with ADHD and controls were compared. Further, performances among the groups of ADHD predominantly inattentive(ADHD-IA)(n=40), predominantly hyperactive-impulsive(ADHD-HI)(n= 10), and combined type(ADHD-C)(n=31), were compared. Results : Scores of Finger windows forward task were lower in the ADHD group as compared to the control group, whereas, the Digit span forward showed no difference. Both scores of Digit span backward and Finger windows backward task were lower in the ADHD group than the controls. Children with ADHD-IA performed poorer than children with ADHD-C on the Finger windows backward task. Conclusion : The results of this study showed that children with ADHD have deficits in spatial short-term memory and verbal and visuospatial working memory when compared to normal children. The deficits were evident in children with ADHD-IA subtype and in particular, performance on the visuospatial working memory task in this group was poorer than the ADHD-C group.

• Anxiety and mood
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• v.8 no.2
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• pp.120-126
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• 2012

Objective : Previous studies reported a correlation between the low serum cholesterol level and impulsive behaviors. In this study, we investigate an association between the serum lipid levels and psychological parameters in maladaptive soldiers in the Korean Army. Methods : A total of ninety-six maladaptive subjects and thirty-six normal controls in the Korean army were evaluated with the Korean version of Barratt Impulsiveness Scale (K-BIS), Korean version of Beck Suicidal Ideation Scale (K- BSIS), Korean version of Beck Depression Inventory (K-BDI) and Korean version of Beck Anxiety Inventory (K-BAI). Serum total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL) and high density lipoprotein (HDL) level were measured by overnight fasting blood sampling. Results : There were no significant differences between the groups in demographic characteristics. Serum total cholesterol levels (t=-2.209, p=0.032), triglyceride levels (t=-4.593, p<0.001), and LDL levels (t=-3.753, p=0.001) of maladaptive subjects were significantly lower than those of normal controls, and maladaptive subjects had higher K-BIS scores than normal controls (t=7.542, p<0.001). Negative correlation was found between LDL levels and non-planning impulsiveness in the maladaptive subjects (r=-0.253, p=0.013). LDL levels (${\beta}=-0.258$, p=0.008) and K-BDI scores (${\beta}=0.266$, p=0.043) emerged as significant predictors for non-planning impulsiveness. Conclusion : These results suggested that LDL level was associated with non-planning impulsiveness. These findings suggested that serum cholesterol levels might be available as a biological marker of impulsiveness. However, more large samples, longitudinal biological study and psychiatric evaluations should be needed to develop a preventive intervention for maladaptive male conscripts in the Korean army.

• Transactions of the KSME C: Technology and Education
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• v.3 no.1
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• pp.37-44
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• 2015

In this paper dynamic deformation of lower hinge of refrigerator is simulated using dynamic finite element analysis while refrigerator is being dropped. The flow stress curves considering velocity dependency of hinge and lower packing material are determined through bending test and compression test at several dropping speeds. The determined material properties and flow stress from reverse engineering were used as input data for refrigerator's drop test using a dynamic finite element analysis software LS-DYNA. Additionally the result between CAE and 3D deformation measurement from real refrigerator drop test are compared and the result shows that the proposed analysis model is very useful to design lower hinge and lower packing endurable to the impulsive drop impact.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.3
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• pp.131-139
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• 1992

By introducing a body potential, the high-oder spectal method of Dommermuth and Yue(1987) is extended to treat the nonlinear interactions between the free surface and the submerged cylinder. A 2-dimensional numerical wave tank is developed based on this numerical scheme, and applied to the wave resistance problem and the wave maker problem. In the simulations, it is shown that the transient waves due to the impulsive start of the body motion make a practical obstacle to the acquisition of useful data from the numerical experiments. Gradual starting procedures are devised, and successful result of the quasi-steady state or the uniform regular wave group was obtained. Within the author's present knowledge, the present numerical scheme is one of the most efficient numerical schemes which can treat the nonlinear interactions between the free surface and the body motion in time-domain.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.26 no.3
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• pp.217-225
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• 2015

Objectives : The objective of this study was to compare the Korean Personality Rating Scale for Children (K-PRC) profile between children with attention-deficit hyperactivity disorder (ADHD) and typically developing children. We also aimed to investigate the association of K-PRC and ADHD symptoms. Methods : Ninety-nine youth (age $8.3{\pm}2.4$ years, 72 boys) with ADHD and 84 controls (age $9.2{\pm}2.5$ years, 43 boys) were recruited from the Department of Pediatric Psychiatry of the Asan Medical Center Children's Hospital. Diagnoses of ADHD and comorbid psychiatric disorders were confirmed with the Kiddie-Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version (K-SADS-PL). The parents of the subjects completed the ADHD rating scale, and K-PRC. Independent t-tests, analysis of covariance, partial correlation analyses, and Mc Nemar test were used for analysis. Results : Children and adolescents with ADHD showed higher K-PRC scores in verbal development, physical development, depression, delinquency, hyperactivity, family dysfunction and psychoticism. Delinquency and hyperactivity were significantly correlated with parent-rated ADHD rating scales and ADHD scores on K-SADS-PL. The hyperactive/impulsive and combined subtypes showed higher scores on hyperactivity and delinquency than the inattentive subtype, and the inattentive subtype showed higher scores on depression and social dysfunction of the K-PRC. Conclusion : Our results suggest that K-PRC could be used to comprehensively evaluate symptoms, combined psychopathologies, developmental delay and family dysfunction of children with ADHD.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.21 no.2
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• pp.72-79
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• 2010

Objectives : The purpose of this study was to examine the difference in functional impairment between children with attention-deficit hyperactivity disorder (ADHD) and normal controls, and to compare the functional impairment across ADHD subtypes. Methods : Children and adolescents with ADHD between the ages of 6 and 18 years were recruited for the study. Parents and teachers of the ADHD subjects completed the parents' and teachers' forms of the Children and Adolescents Functioning Impairment Scale (CAFIS), respectively. The results of these scales were compared to those of normal controls. Results : Subjects included 110 children with ADHD, predominantly inattentive type (ADHD-IA) ; 23 with ADHD, predominantly hyperactive-impulsive type (ADHD-HI) ; and 60 ADHD, combined type (ADHD-C). When compared to 41 normal controls, there were significant differences in CAFIS-parent and CAFIS-teacher scales for the ADHD group. Functional impairment in the family relationship as rated by the parents was higher in children with ADHD-C when compared to that of children with ADHD-IA. Conclusion : In comparison to normal children, children with ADHD have a higher level of impairment in several functional areas, and differences exist in functional impairment across ADHD subtypes. Further, ratings of functional impairment between parents and teachers were inconsistent. Thus, gathering information from the teachers is important when diagnosing or establishing treatment regimens for ADHD.

• The Journal of the Acoustical Society of Korea
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• v.32 no.3
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• pp.269-278
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• 2013

The speech recording of the National Archives of Korea contains very important traces which represent modern times of Korea. But the way to be recorded by analogue is easily contaminated as time goes by. So it has to be digitalized for management and services. Consequently, restoration method of distorted speech is needed. We propose the four classes for each distortion kind and apply restoration algorithms for the cases of speech level, stationary noise and abrupt noise. As a result, speech volume adjusts to -26 dBov for only on the speech region and SNR improves above 10dB. Especially, conventional way to remove the noise is almost impossible because we need to listen to all of them but it can be more effective by adaptation of auto restoration algorithm.

• Journal of the Korean Vacuum Society
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• v.19 no.3
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• pp.169-176
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• 2010

Cryopumps can provide economical profits with a relatively high pumping speed per size. However, it is somewhat doubtful that pumping performance of cryopums, which is very sensitive to the temperature of the adsorption panel, can be maintained or recovered fast for large continuous or impulsive gas loads. The official evaluation items indicating cryopump performance for gas loads are the maximum throughput and the crossover value. There are two other, unofficial but widely used, items, the Ar recovery time and gulp characteristics. Although these evaluation items look absolutely different with each other, there are close relations and even duplications in their test schemes. Therefore, it is necessary to study how to improve practically each test procedure, and combine or unify some procedures.