• Proceedings of the KSME Conference
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• 2001.06a
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• pp.157-162
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• 2001

Fretting is a potential degradation mechanism of structural components and equipments exposed to various environments and loading conditions. The fretting degradation, for example, can be observed in equipments of nuclear, fossil as well as petroleum chemical plants exposed to special environments and loading conditions. It is well known that a cast stainless steel(CF8M) used in a primary reactor coolant(RCS) degrades seriously when that material is exposed to temperature range ken $290^{\circ}C{\sim}390^{\circ}C$ for long period. This degradation can be resulted into a catastrophical failure of components. In the present paper, the characteristics of the fretting fatigue are investigated using the artificially aged CF8M specimen. The specimen of CF8M are prepared by an artificially accelerated aging technique holding 1800hr at $430^{\circ}C$ respectively. Through the investigations, the simple fatigue endurance limit of the virgin specimen is not altered from that obtained from the fatigue tests imposed the fretting fatigue. The similar tests are performed using the degraded specimen. The results are not changed from those of the virgin specimen. The significant effects of fretting fatigue imposed on both virgin and degraded specimen on the fatigue strength are not found.

• Resources Recycling
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• v.12 no.4
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• pp.44-50
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• 2003

Separation of mixed plastics is not a simple task due to similarities of specific gravity and limitations of sizes, etc. In this study, a new technique was developed to separate plastics selectively by a thermal adhesion method using the different softening or melting temperatures of various types of plastics. Tests were conducted to investigate softening or melting temperatures and adhesion probabilities of plastics with change in temperature. Tests also were conducted to analyze the operating variables, including contact times, size and color pigment. It was founded that LDPE, HDPE and PVC, PET, etc among mixed plastics could be separated selectively according to the change of temperature.

• The Journal of Pediatrics of Korean Medicine
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• v.20 no.2
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• pp.147-175
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• 2006

Objective : This study is to investigate the method for assesment and diagnosis of ADHD, especially focusing on behavior rating scales. Methods : We searched the recent date of the publication and paper in ADHD. Results : For Assesment and Diagnosis of ADHD, various method such as interview with parents, child and teacher, behavior observation, behavior rating scales and neuropsychological test are used. The structured interview consists of the restrictive questions and response, and then have diagnostic algorithm, consequently can be used by untrained clinicians. Of the structured interview, standardization of K-SADS in Korean version is finished. Behavior rating scales, the form of parent, teacher and self-report questionnaires, are used as diagnosis and treatment evaluation of ADHD. Behavior rating scales consist of both ADHD-specific scales and broad-band scales designed to screen for various symptoms (including ADHD symptoms). ADHD-specific scales are useful in differential diagnosis, discrimination of subtype, treatment evaluation, However, broad-band scales are useful in preliminary examination. The neuropsychological tests can evaluate attention deficit and effect of attention deficit on cognitive function and academic performance. The neuropsychological tests also used in diagnosis and treatment evaluation of ADHD. Conclusion : For Assesment and Diagnosis of ADHD, various method are used, especially behavior rating scales are both useful and simple tool for diagnosis and treatment evaluation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.7
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• pp.517-524
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• 2014

Micro-vibration induced by on-board equipments such as fly-wheel and cryogenic cooler with mechanical moving parts affects the image quality of high-resolution observation satellite. Micro-vibration isolation system has been widely used for enhancing the pointing performance of observation satellites. In general, the micro-vibration isolation system requires a launch locking mechanism additionally to guarantee the structural safety of mission payloads supported by the isolation system with low stiffness under launch environment. In this study, we propose a passive launch and on-orbit vibration isolation system using shape memory alloy mesh washers for the micro-vibration isolation of spaceborne compressor, which does not require the additional launch locking mechanism. The basic characteristics of the isolator were measured in static and free vibration tests of the isolator, and a simple equivalent model of the isolator was proposed. The effectiveness of the isolator design in a launch environment was demonstrated through sine vibration, random vibration and shock tests.

• Journal of the Korea Safety Management & Science
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• v.15 no.2
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• pp.63-69
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• 2013

The purposes of this study are to survey stereotypes of control-display relationships for seven principal controls in passenger cars using the paper-pencil and hardware tests, and to examine stereotype strength of the paper-pencil test through comparing the stereotypes for the controls derived by the two methods. Ninety two and 60 college-aged students participated in the paper-pencil test and the real car simulation of the hardware test, respectively. There are dominant motion-directions for all controls in the paper-pencil test, while in the hardware test, there are dominant motion-directions for six controls including head light, high beam, door window, ignition key, door key and door lock controls. The stereotypes of motion-directions for six controls obtained by the paper-pencil test were the same as or similar to those by the hardware test. It was inferred from this that the congruence of the stereotypes by the two methods might be attributed to two simple motion-direction principles of 'clockwise for increase' and 'upward for increase.' Although it is known that the hardware test would be best for obtaining accurate stereotypes between controls and displays, this study implies that if the paper-pencil test is well designed, the paper-pencil test can produce the same results as the hardware test at low cost and without consuming time.

• Proceedings of the Korean Reliability Society Conference
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• 2004.07a
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• pp.239-246
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• 2004

Accelerated degradation test (ADT) can be a useful tool for assessing the reliability when few or even no failure are expected in an accelerated life test. In this paper, MLCC (Multilayer Ceramic Capacitors), a sort of passive components which have large capacitance(X7R -55$^{\circ}C$~1$25^{\circ}C$) have been tested, and least-square analyses are used to illustrate our approach in which amount of degradation of a DUT following log-normal distribution. We assumed a simple and useful linear model to describe the amount of degradation over time subjected to different voltage levels applied. Tests for linearity of the performance-time relationship, and provide tests for how well the assumptions hold. Also, by using Eyring Model, MLCC's mean life time is assessed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.1 s.28
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• pp.61-67
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• 2007

This paper describes the implementation procedures and results of Fishery Safety and Security System to secure an aquaculture area from a thief. The system designed with various functional modules to implement selectively available system providing low cost to high cost and simple function to high function according to user's requirement in a practical fishing fields. In the abalone farm field located in Jin island, Jeonranam province and having condensed aquaculture facilities with 50 cages (10 row by 5 column) within 0.5 miles from coast, practical field tests are carried out. As results from that tests, it is found that the system can guard not only the whole area of cultivating farm field but also each cages with detail.

• Journal of Adhesion and Interface
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• v.5 no.2
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• pp.5-14
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• 2004

Since flexible adhesives are used more and more in structural applications, designers should have a better understanding of its behaviour under various conditions as ultimate load, fatigue load, long-term load and environmental conditions. This paper focuses on long-term load conditions and its effect on flexible adhesives. The creep properties of both PU (PolyUrethane) and SMP (Silyl Modified Polymers) adhesives used for identical applications are considered. To investigate the creep behaviour tests under various conditions were done. The results of those tests are presented and compared. To evaluate these results an empirical method is proposed and discussed. An example illustrates the potential of this method. It is also shown that with use of a probabilistic calibration technique this method results into a simple rule, which can be used to calculate the creep for practical applications. For the studied adhesives, the creep performance of the SMP adhesive is shown to be of the same level or slightly better than of the two PU adhesives. In addition to this empirical method, the principles of a more complex theoretical based method are introduced. The potential of this method is illustrated and future research activities are drawn.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1124-1131
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• 2008

Thanks to a new in-situ seismic probe, using bender elements and penetration scheme, a simple linear relationship between undrained shear strength(Cu) and shear wave velocity(Vs) was obtained. This priceless relationship is worthy to be illuminated further in ideal laboratory environment. To avoid sampling disturbance effect, special consolidation cylinders were used to make normally consolidated specimens from kaolinite suspension. The undrained shear strengths of the specimens were measured using unconsolidated undrained triaxial compression tests. Also shear wave velocity measurements were performedprior to shearing the same specimens, using the bender elements installed in the base pedestal and the top cap of the triaxial compression cell. The Cu-Vs relationship is fairly linear and supports the linear trend of clayey silt obtained using field testing. Also the classic density-shear modulus relationship for soft clay proposed by Hardin and Black(1969) was once more verified hereby.

• Structural Engineering and Mechanics
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• v.53 no.2
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• pp.189-204
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• 2015

After the large destruction of Lisbon due to the 1755 earthquake, the city had to be almost completely rebuilt. In this context, an innovative structural solution was implemented in new buildings, comprising internal timber framed walls which, together with the floors timber elements, constituted a 3-D framing system, known as "cage", providing resistance and deformation capacity for seismic loading. The internal timber framed masonry walls, in elevated floors, are constituted by a timber frame with vertical and horizontal elements, braced with diagonal elements, known as Saint Andrew's crosses, with masonry infill. This paper describes an experimental campaign to assess the in-plane cyclic behaviour of those so called "frontal" walls. A total series of 4 tests were conducted in 4 real size walls. Two models consist of the simple timber frames without masonry infill, and the other two specimens have identical timber frames but present masonry infill. Experimental characterization of the in-plane behaviour was carried out by static cyclic shear testing with controlled displacements. The loading protocol used was the CUREE for ordinary ground motions. The hysteretic behaviour main parameters of such walls subjected to cyclic loading were computed namely the initial stiffness, ductility and energy dissipation capacity.