• 한국표면공학회지
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• 제25권6호
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• pp.309-317
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• 1992

Evaluation of electroplated gold has been carried out to obtain the data base for electrical, mechanical and environmental properties for telecommunication component applications. Gold plating was performed to a various thickness of $0.1\mu\textrm{m}$ to 1.$25\mu\textrm{m}$ after Ni plating of $3\mu\textrm{m}$ on C52100 bronze. Electrical properties were evaluated by measuring contact resistance using 4-wire method under static contact and dynamic contact during wear. Reciprocating wear test was performed to study the wear behavior as well as failure of gold contacts. Environmental characteristics were evaluated by using salt spray testing and SO2 test. Hardness of soft gold film was measured to be 53KHN under 5g load. Friction coefficient was initially obtained to be 0.15 and 0.25 under 100g and 200g loads respectively, and then raised up to 0.8 with increasing reciprocating wear cycles. Static contact resistance was 2 to 3m$\Omega$ regardless of gold film thickness while drastic changes of contact resistance were occured upon stripping of the gold film during wear. The lifetime of contact wear showing stable contact resistance increased up to 6 times for $1\mu\textrm{m}$ thickness compared to that of$ 0.1\mu\textrm{m}$ thickness under 100g load. All gold plating appeared to be stable under salt atmosphere while only the gold plating over 1$\mu\textrm{m}$ was stable under SO2 atmosphere.

• Journal of Magnetics
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• 제17권4호
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• pp.245-250
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• 2012

Ferromagnetic resonance and X-ray specular reflectivity measurements were performed on $Ni_{81}Fe_{19}/Ir_{20}Mn_{80}/Co_{90}Fe_{10}$ exchange bias trilayers, which were grown using the pulsed-DC magnetron sputtering technique on Si(100)/$SiO_2$(1000 nm) substrates, to investigate the evolution of the interface roughness and exchange bias and their dependence on the NiFe layer thickness. The interface roughness values of the samples decrease with increasing NiFe thickness. The in-plane ferromagnetic resonance measurements indicate that the exchange bias field and the peak-to-peak line widths of the resonance curves are inversely proportional to the NiFe thickness. Furthermore, both the exchange bias field and the interface roughness show almost the same dependence on the NiFe layer thickness. The out-of plane angular dependent measurements indicate that the exchange bias arises predominantly from a variation of exchange anisotropy due to changes in interfacial structure. The correlation between the exchange bias and the interface roughness is discussed.

• Journal of Mechanical Science and Technology
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• 제17권9호
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• pp.1316-1323
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• 2003

This paper presents a structural analysis on the rigid and deformed motion of the leaflet induced by the blood flow required in the design of a bileaflet mechanical heart valve (MHV) prosthesis. In the study on the design and the mechanical characteristics of a bileaflet mechanical heart valve, the fluid mechanics analysis on the blood flow passing through leaflets, the kinetodynamics analysis on the rigid body motion of the leaflet induced by the pulsatile blood flow, and the structural mechanics analysis on the deformed motion of the leaflet are required sequentially and simultaneously. Fluid forces computed in the previous hemodynamics analysis on the blood flow are used in the kinetodynamics analysis on the rigid body motion of the leaflet. Thereafter, the structural mechanics analysis on the deformed motion of the leaflet follows to predict the structural strength variation of the leaflet as the leaflet thickness changes. Analysis results show that structural deformations and stresses increase as the fluid pressure increases and the leaflet thickness decreases. Analysis results also show that the leaflet becomes structurally weaker and weaker as the leaflet thickness becomes smaller than 0.6 mm.

• 한국가구학회지
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• 제24권4호
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• pp.379-388
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• 2013

In this study, the effect of various glass fiber (GF) contents in a shell layer and shell thickness changes on the flexural property of coextruded wood plastic composites (WPCs) in combination with three core systems (weak, moderate, and strong) was investigated. GF behaved as an effective reinforcement for the whole coextruded WPCs and GF alignments in the shell layer played an important role in determining the flexural property of the coextruded WPCs. At a given shell thickness, the flexural property of the whole coextruded WPCs was improved with the increase of GF content in shell. For core quality, when the core is weak, increase of GF content in shell led to improved flexural property of the whole composites and increase of shell thickness helped it. On the other hand, when the core is strong, the flexural property of the whole composites showed reduced features at low GF content in shell and increase of shell thickness aggravated it. This approach provides a method for optimizing performance of the coextruded WPCs with various combinations of core-shell structure and properties.

• Restorative Dentistry and Endodontics
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• 제15권2호
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• pp.34-45
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• 1990

The purpose of this study was to evaluate the pulpal responses of S. mutans (6715, serotype A) in relation to the remaining dentin thickness. The material was consisted of 72 teeth from 6 dogs. Cl. V cavities were prepared into 2 different thickness (0.5mm, 1.0mm) of remaining dentin. In the control groups, the cavities were filled with filter paper of broth, tin foil, and IRM$^{(R)}$ cement. In the experimental groups, the cavities were filled with filter paper of S. mutans, filter paper of broth, tin foil, and IRM$^{(R)}$ cement. The intervals of observation period were 1 week, 3 weeks, and 8 weeks respectively after the experiment. The specimens were fixed with 10% formalin and decalcified in 5% nitric acid. All specimens were stained with Hematoxylin-Eosin and examined histopathologically under the microscope. The results were as follows. 1. The changes and congestion of odontoblastic layers were more frequent and lasting in the control group of 0.5mm than in that of 1.0mm remaining dentin thickness. 2. There was no characteristic difference between the control group of 1.0mm and the experimental group of 1.0mm in all pulp responses. 3. Acute and chronic inflammatory cells were seen in the experimental group of 0.5mm, but not seen in the control group of 0.5mm.

• 한국전문물리치료학회지
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• 제22권4호
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• pp.79-86
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• 2015

This study examined the effects of trunk stabilization exercise on balance and trunk control in children with spastic diplegia. Four children with ambulatory spastic diplegia participated in the trunk stabilization exercise program using a Both Sides Utilized (BOSU) ball, 30 minutes a day, two times a week for eight weeks. Outcome variables included the pediatric balance scale, trunk control movement scale and multifidus thickness using ultrasound image. After trunk stabilization exercise, there was statistically no significant improvement in pediatric balance scale, trunk control movement scale and multifidus thickness. However, individual outcomes were observed with some positive changes. Balance, trunk control movement, and thickness of multifidus were found to be improved. Trunk stabilization exercise using a BOSU ball could improve trunk control and increase the thickness of multifidus in children with spastic diplegia. Further investigation is needed to evaluate subjects according to type of cerebral palsy and to understand the relationship between postural control and gait.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2738-2743
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• 2008

We conducted a study by computational simulation about the effects of frost thickness on the pressure drop and heat transfer characteristics as whole heat exchanger configuration changes. In order to perform the analysis for validation, we assumed that frost properties have constant values and the frost layers that are formed on the fin and tube surfaces are uniform. In order to find the constant thermal conductivity of frost layer, a variety of frost thermal conductivities are performed in our work and compared with the results by Lee et al. [4] and Yang et al. [5] proposed many experimental data about the 2-rows and 2-columns finned tube heat exchanger. The numerical results agreed well with the experimental data when frost conductivity is 0.07W/mK. After the validation had performed, we applied this procedure to the finned tube heat exchanger of domestic refrigeration and investigated the thermo-hydraulic characteristic of the heat exchanger affected by frost thickness according to the inlet velocities and temperatures of air considering the configuration change such as fin pitch.

• 사상체질의학회지
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• 제27권2호
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• pp.240-253
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• 2015

Objectives The aim of this study was to investigate the effects of GalGunSeungGi-Tang (GST) on allergic contact dermatitis (ACD) induced by 2,4-dintrochlorobenzone (DNCB) Methods In this study, The changes of body weight, ear weight, ear thickness, spleen weight, dorsum skin thickness, symptom score by eyesight, histological finding, proliferation rates of splenocyte in vitro and in vivo are investigated to check effects of GST. The mice are divided into four group; Normal (naive mice), Control (DW administered), GST-L (GST 500mg/Kg/day administered), GST-H (GST 1,000mg/Kg/day administered). Results GST inhibited weight of ear significantly (P < 0.05) and also thickness (P < 0.01). In addition, There are significant decrease in thickness of dorsum skin and proliferation rates of splenocyte in vivo in GST administered group. Finally, GST reduced symptom score and hyperkeratosis, hyperpigmentation, increase of granulocyte and parakeratosis in histological finding. Conclusions These results suggest that GST can decrease symptoms of ACD.

• 한국표면공학회지
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• 제29권5호
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• pp.301-313
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• 1996

The texture of vapor deposits(PVD and CVD) changes from the orientation that places the lowest energy lattice plane parallel to the substrate under the condition of low atom or ion concentration adjacent to the deposit, to the orientation that places the higher energy crystal planes parallel to the substrate as the atom or ion concentration adjacent to the deposit increases. However, in the early stage of deposition, the deposit-substrate interface energy and the surface energy constitute the most important energies of the system. Therefore, if the lattice match is established between the substrate and the deposit without generating much strain energy, the epitaxial growth takes place to reduce the interfacial energy. When the epitaxial growth does not take place, the surface energy is dominant in the early stage of deposition and the lowest energy crystal plane tends to be placed parallel to the substrate up to a critial thickness. The thickness depends on the deposition condition. If the deposition condition does not favor placing the lowest energy crystal plane parallel to the substrate, the initial texture will change to that compatible with the deposition condition as the film thickness increases, and the texture turnover thickness will be short. The microstructure and surface topography of deposits are related to their texture.

• 한국식품저장유통학회지
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• 제1권1호
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• pp.15-20
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• 1994

This experiment was carried out to select the optimum thickness of polyethylene film for the nonastringency of astringent persimmon fruits during modified atmosphere(MA) storage of Cheongdo Bansi kept at 0$^{\circ}C$. The experimental plots were divided into 5 plots by film thickness(0.08, 0.10, 0.12, 0.14 and 0.16mm). The experimental items were the changes in concentration of CO2 and O2 in film brig, soluble tannin contents, loss of weight firmness and external appearance of fruits. The nonastringency of persimmon fruits can be achieved all groups excepting the 0.08mm film during MA storage. The sweet persimmon in film bag of 0.10 and 0.12mm maintained a high quality and firmness, but following the deastringency the fruits in 0.14 and 0.16mm developed off-color. The increasing of carbon dioxide level and decreasing of oxygen level in film bag created anaerobic condition at earth stage, and then it kept a constant level during stooge. According to film thickness the obvious difference in the change of soluble tannin contents external appearance and firmness were observed. It could be concluded that the optimum thickness of film for the desirable nonastringency on Cheongdo Bansi was 0.10mm.