• Journal of the Korean Society of Child Welfare
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• no.58
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• pp.205-229
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• 2017

The purpose of this study was to examine gender differences in the impact of exposure to peer delinquency among elementary school-age students and the mediating effects of aggression. The study utilized 458 cases (220 male students, 238 female students) of data from the 2015 Korea Welfare Panel Study (KoWePS) conducted by the Korea Institute for Health and Social Affairs (KIHASA). The theoretical frameworks used in this study included Bandura's social learning theory, Akers' social learning theory, and Sutherland's differential association theory. The findings were as follows. First, there was no statistically significant effect on peer group's delinquency experience overall, aggression, and delinquency experience by gender. Second, male students' delinquency experience of their peer group had a statistically significant effect on their delinquency, however, this was not true for female students. Third, in the case of male students, aggression was found to mediate the relationship between peer group delinquency experience and their own delinquency, but not for female students. From these findings, we suggest a practical and policy-driven intervention plan, focusing on reducing the contact frequency of delinquency experience and aggression, The purpose of this study was to examine gender differences in the impact of exposure to peer delinquency among elementary school-age students and the mediating effects of aggression. The study utilized 458 cases (220 male students, 238 female students) of data from the 2015 Korea Welfare Panel Study (KoWePS) conducted by the Korea Institute for Health and Social Affairs (KIHASA). The theoretical frameworks used in this study included Bandura's social learning theory, Akers' social learning theory, and Sutherland's differential association theory. The findings were as follows. First, there was no statistically significant effect on peer group's delinquency experience overall, aggression, and delinquency experience by gender. Second, male students'delinquency experience of their peer group had a statistically significant effect on their delinquency, however, this was not true for female students. Third, in the case of male students, aggression was found to mediate the relationship between peer group delinquency experience and their own delinquency, but not for female students. From these findings, we suggest a practical and policy-driven intervention plan, focusing on reducing the contact frequency of delinquency experience and aggression, which was found to adversely affect elementary school students' delinquency.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.12-12
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• 2017

본 연구에서는 롤러식 양파 파종기의 작동 특성 파악을 위한 동적 시뮬레이션을 수행하였다. 롤러식 양파 파종기의 주요부는 롤러와 포트트레이로 구성된다. 양파 파종기의 작동 특성 파악을 위해 동력전달 경로의 구성요소와 각 주요부의 속도를 분석한 결과 동력원인 모터의 출력은 체인과 스프라켓을 통해 포트트레이와 롤러에 전달되며 모터에서의 회전속도는 1770rpm으로 감속기를 통해 출력축의 회전속도는 17.7rpm으로 감소한다. 이론적으로 도출한 포트트레이의 이동속도는 74.98mm/s, 롤러의 회전속도는 22.13rpm으로 나타났다. 시뮬레이션을 수행하기 위해 스캐너를 이용하여 롤러식 파종기를 실측했으며 후에 3D모델링을 진행하였다. 시뮬레이션 해석조건은 파종기의 실제 작동방식을 고려하여 롤러1과 3은 포트트레이와 면대면 접촉을 통해 회전하도록 설정하였고 롤러2와 롤러4는 동력전달경로에 포함된 스프라켓과 기어의 잇수비를 반영하여 회전속도를 도출하여 적용하였다. 시뮬레이션 결과 롤러의 회전속도는 모두 22.13rpm으로 수식에 근거하여 도출한 값과 계측 값이 같음을 확인하였다. 또한 파종 깊이를 결정하는 요소인 롤러의 상토 압축 정도를 파악하기 위하여 롤러궤적 시뮬레이션을 통해 롤러 끝 단의 궤적을 분석하였는데 롤러궤적 분석 결과 롤러의 끝 단은 약 9.8mm 깊이로 내려가는 것을 확인하였다.

• 전자공학회논문지 IE
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• v.44 no.3
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• pp.42-50
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• 2007

In this paper, elastic and plastic adhesion index was very important in deciding adhesive characteristics and varying elastic and plastic index, dimensionless load and pull-off force were analyzed and simulated. Finally, using AFM, experimental surface roughness parameters of substrates and pull-off force between tip and substrates were produced. Using these values, pull-off forces were calculated and were compared with experimental pull-off forces. Through simulation and experiment, it was found that interaction of asperity also had very important influence on adhesive contact.

• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.155-163
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• 2001

A number of screws are inevitably used for tightening flanges in constructing a vacuum system. A theoretical relation between the axial force and the torque exerted on a screw is easily obtained assuming that the friction force generated on the contacting plane is known, however, in practice the friction is influenced strongly by unknown detailed surface condition. It is difficult to tighten optimally and uniformly the flange seals if the screws commercially available have undefined surface conditions and scattered dimensions, and the axial force produced by the screws can not be expected properly. In this paper a scatter of the axial force over screws and the deviation from an expected one, depending on various fastening conditions, are investigated using a variety of M8, the most popular size for vacuum flanges, domestic stainless screws of hexagonal head and standard thread.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.6
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• pp.725-731
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• 1985

In this study the rigid-plastic finite element method is used in order to study the deformation characteristics of solid cylinder upsetting. The effects of friction and aspect ratios on the effective strain distribution, axial stresses at the die-material interface, radial displacements, strain components, grid distortion on the meridional cross-section and gradual changes of outer profile are studied analyzed and compared with the experiments for commercially pure aluminum and .alpha.-brass. The agreement between numerical (or theoretical)and experimental results is shown to be acceptable for the engineering purpose.

• Journal of the Korean Society for Nondestructive Testing
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• v.14 no.2
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• pp.90-100
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• 1994

Ultrasonic velocities are widely used in the investigation of material properties. In this paper, a micromechanics model and the ultrasonic velocity were used to develop a nondestructive method to determine the density variation due to porosity in structural SiC. The micromechanics model developed can consider the pore shape and orientation. The model also takes into account the interaction between pores so that it can be applied to the material with high porosity content. A contact pulse overlap method was used to measure the ultrasonic velocities of porous SiC samples, and there was a linear correlation between the velocity and density (or porosity). Using the model and the measured velocity, the bulk density can be easily calculated. The calculated density was in good agreement with that obtained by Archimedes' method.

• The Journal of the Acoustical Society of Korea
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• v.9 no.3
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• pp.24-30
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• 1990

In this paper, meander line type EMAT(Electro-Magnetic Acoustic Transducer) has been designed and fabricated with effective properties for detecting flaw existing within one wavelength in depth, and its characteristics have been analyzed. For the purpose of getting effective dynamic and static magnetic intensity, the coil has been arrayed using wire with interval of 0.75 mm and width of 0.65 mm and permanent magnets with 1500 Gauss have been constructed respectively. The center frequency and fractional bandwidth of the fabricated EMAT was 2 MHz and 36% respectively and its impulse response has been measured by non-contacting technique(the distance between the conducting media and the coil was 0.15mm). In the measuring results, it has been shown that Insertion Loss(IL) was 45.46dB and it was good agreement with theoretical result.

• Journal of the Korean Society for information Management
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• v.29 no.2
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• pp.93-112
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• 2012

This study focuses on the characteristics of information seeking behavior through the casual interactions which are regular contacts with others as information sources in the context of ELIS. Qualitative data were gathered using semi-structured one-to-one interviews with 9 wild-goose mothers in order to investigate the casual interactions. We identified information needs, patterns and characteristics of information seeking behavior through the casual interactions and the major interpretative repertoires.

• 한국정보통신설비학회:학술대회논문집
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• 2004.08a
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• pp.6-10
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• 2004

회전기기의 운전 상태에서 on-line 부분 방전시험은 고정자 권선의 절연상태를 검사, 평가 할 수 있는 중요한 수단으로서 이러한 부분방전시험을 통하여 회전기기 시스템의 사고예방을 위한 진단을 할 수 있다. 기존의 비접촉식 센서인 SSC는 부분방전 측정을 위하여 권선의 웨지 아래에 설치하는 방식으로 개발되어 [1], 설치가 불편하고 Global VPI 방식으로 제작된 소형 회전기에는 설치할 수 없는 단점이 있다. 본 논문에서는 소형 회전기에 사용가능한 저, 고주파용 부분방전 센서를 제안하였다. 웨지 위에 설치 가능한 SSC 형태의 마이크로스트립 센서 및 전송선로 이론을 이용한 2선 평행 전송선로 센서는 값이 싸고 소형 회전기에 설치할 수 있을 정도의 크기를 지니며, 기본적으로 센서의 구조가 고주파 웨이브가이드로서 고주파용 센서로 적합하다. 또한 저주파 신호를 검출하기 위한 센서로 로고우스키 코일 형태의 U 타입 센서는 와전류를 검출하는 센서로서 슬롯 외부에 설치 되어야 한다. 이러한 U 타입 센서와 마이크로스트립 센서 또는 2선 평행 전송선로를 동시에 설치할 경우 저, 고주파를 효과적으로 검출할 수 있다.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.2 s.191
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• pp.95-102
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• 2007

A feeding system is a key component in manufacturing packing boxes such as printing, slotting and gluing. The role of the feeding system is to feed corrugate cardboards which is usually tick and large. So, a special method is necessary to feed corrugate cardboards. This paper suggests a concept and an automatic feeding machine to feed corrugated cardboards using TRIZ, the theory of inventive problem solving. The automatic feeding machine consists of units to regulate the machine according to length and width of corrugated cardboards, a feeding part with a plurality of small rollers, and a sucking part which intensify frictional force between rollers and the lowest feeding cardboard. In particular, the feeding part is composed of an up-and-down motion plate with holes to suck the lowest corrugated cardboard as well as small rolling rollers after stopping in a moment. Thus this machine does not sensitive to size of corrugated cardboards and also can keep feeding accuracy during feeding fast.