• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.322-329
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• 1999

The hydrodynamic theory of dentin sensitivity states that movement of tubular contents or tubular fluid, in either direction of dentinal tubule, causes dentin sensitivity. A corollary of that theory is that anything that can decrease dentinal fluid movement or dentin permeability should decrease dentin sensitivity. A wide variety of physicochemical methods have been used to reduce the permeability and sensitivity of exposed dentin. The purpose of this study was to evaluate the ability of 4 kinds of clinical desensitizing agents(2% NaF, 30% Potassium oxalate, MS Coat$^{(R)}$, Tubulitec system$^{(R)}$) to reduce the rate of fluid flow through dentin in vitro. Sixty coronal dentin discs, 1mm in thickness, were prepared from extracted third molars, free from decay and wear. Dentin discs were treated with 3% EDTA(Tubulicid Plus$^{(R)}$(Dental Therapeutics AB, Sweden)) to remove the smear layer and debris occluding the tubular orifices. After placing the discs in a split chamber device, the rate at which physiologic saline solution could filter across dentin under 150cm $H_2O$ hydrostatic pressure was measured. The occlusal side of the discs were then treated with MS Coat$^{(R)}$, 2% NaF, Tubulitec system$^{(R)}$, and 30% Potassium oxalate, and the filter ratio of the saline solution was measured again. The following conclusions were drawn : 1. Hydraulic conductance which was measured after the application of desensitizing agents was decreased in all the groups(p<0.05). 2. % change of hydraulic conductance was compared but no significant difference was found among the four desensitizing agents(p>0.05). 2% NaF, 30% Potassium oxalate, MS Coat$^{(R)}$ and Tubulitec system$^{(R)}$ decreased the permeability of dentin. It is considered that above four agents can be used in treating the hypersensitive teeth.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.7
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• pp.48-56
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• 2014

Engine oil is an oil used for lubrication of various internal combustion engines. The main function is to reduce wear on moving parts; it also cleans, inhibits corrosion, improves sealing, and cools the engine by carrying heat away from moving parts. In engines, there are parts which move against each other. Otherwise, the friction wastes the useful power by converting the kinetic energy to heat. Those parts were worn away, which could lead to lower efficiency and degradation of the engine. It increases fuel consumption, decreases power output, and can induce the engine failure. This study was conducted to evaluate the relation between engine oil property changes and engine performance for the diesel engine. This test was performed by using 12L, 6 cylinder, heavy duty engines. Low SAPS 10W30 engine oil (two type engine oils) was used. Test procedure and method was in accordance with the modified CEC L-57-T97 (OM441LA) method. In this study, TAN, TBN, KV and metal components, engine power, blowby gas, A_F were presented to evaluate the relation with engine oil property changes and engine performance. TAN, TBN, KV and metal We found that the components were generally increased but engine performance did not change. This results mean that property changes did not affect on engine performance because those were not enough to affect engine performance.

• Journal of the Korean institute of surface engineering
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• v.38 no.3
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• pp.106-111
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• 2005

Ternary Ti-B-C coatings were synthesized on WC-Co and Si wafers substrates by a PECVD technique using a gaseous mixture of $TiCl_4,\;BCl_3,\;CH_4,\;Ar,\;and\; H_2$. The effects of deposition variables such as substrate temperature, gas ratio, $R_x=[BCl_3/(CH_4+BCl_3)]$ on the microstructure and mechanical properties of Ti-B-C coatings were investigated. From our instrumental analyses, the synthesized Ti-B-C coatings was confirmed to be composites consisting of nanocrystallites TiC, quasi-amorphous TiB2, and amorphous carbon at low boron content, on the contrary, nanocrystallites $TiB_2$, quasi-amorphous TiC, and amorphous carbon at relatively high boron content. The microhardness of the Ti-B-C coatings increased from $\~23 GPa$ of TiC to $\~38 GPa$ of $Ti_{0.33}B_{0.55}C_{0.11}$ coatings with increasing the boron content. The $Ti_{0.33}B_{0.55}C_{0.11}$ coatings showed lower average friction coefficient of 0.45, in addition, it showed relatively better wear behavior compared to other binary coatings of $TiB_2$ and TiC. The microstruture and microhardness value of Ti-B-C coatings were largely depend on the deposition temperature.

• Nuclear Engineering and Technology
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• v.41 no.6
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• pp.821-830
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• 2009

In this paper, modal testing and finite element modeling results to identify the modal parameters of a nuclear fuel rod as well as its cladding tube are discussed. A vertically standing full-size cladding tube and a fuel rod with lead pellets were used in the modal testing. As excessive flow-induced vibration causes a failure in fuel rods, such as fretting wear, the vibration level of fuel rods should be low enough to prevent failure of these components. Because vibration amplitude can be estimated based on the modal parameters, the dynamic characteristics must be determined during the design process. Therefore, finite element models are developed based on the test results. The effect of a lumped mass attached to a cladding tube model was identified during the finite element model optimization process. Unlike a cladding tube model, the density of a fuel rod with pellets cannot be determined in a straightforward manner because pellets do not move in the same phase with the cladding tube motion. The density of a fuel rod with lead pellets was determined by comparing natural frequency ratio between the cladding tube and the rod. Thus, an improved fuel rod finite element model was developed based on the updated cladding tube model and an estimated fuel rod density considering the lead pellets. It is shown that the entire pellet mass does not contribute to the fuel rod dynamics; rather, they are only partially responsible for the fuel rod dynamic behavior.

• Journal of Fashion Business
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• v.4 no.1
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• pp.13-24
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• 2000

The purpose of this research is to offer basic data for study of men's suits by investigating the wearing conditions of men's suits. For data collection, a questionnaire was composed of a number of times and the reason of the suit wearing, and a number of suits they posses etc. The subjects of this research were male who aged 20-59 and resided in Seoul and the capital region. The results of the research are summarized as the following : 1. The mean age of suit wearing for the first time is 22.7 years old. The younger began to wear the suits earlier than the older. 2. A number of times of suit wearing for a week is more than 5 days mostly. Being educated higher, the ratio of suit wearing is getting higher. And In the case of job, office men, sales men and men whose job of specialization are wearing suits many a time more than a graduate student and a technician. Most of tne men especially 30's$\sim$40's is wearing the suit as a working garment. 3. Most of men is wearing jacket, dress-shirt and necktie in spring and fall, dress-shirt and necktie in summer, and jacket, vest, dress-shirt and necktie in winter. 4. As a general rule, men have about 2 suits for spring/fall and winter, and about 1 suit for summer. Also male has more than 6 ready-made suits and about 1 custom suit. The last, men almost do not use the suspender with suits.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.9
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• pp.617-625
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• 2009

NAND flash memory is widely used in embedded systems because of many attractive features, such as small size, light weight, low power consumption and fast access speed. However, it requires garbage collection, which includes erase operations. Erase operation is very slow. Besides, the number of the erase operations allowed to be carried out for each block is limited. The proposed garbage collection method focuses on minimizing the total number of erase operations, the deviation value of each block and the garbage collection time. NAND flash memory consists of pages of three types, such as valid pages, invalid pages and free pages. In order to achieve above goals, we use a page rate to decide when to do garbage collection and to select the target victim block. Additionally, We implement allocating method and group management method. Simulation results show that the proposed policy performs better than Greedy or CAT with the maximum rate at 82% of reduction in the deviation value of erase operation and 75% reduction in garbage collection time.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.9
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• pp.72-80
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• 2019

In this task, the tool dynamometer design and manufacture, and the Ansys S/W structural analysis program for tool attachment that satisfies the cutting force measurement requirements of the tool dynamometer system are used to determine the cutting force generated by metal cutting using 3-axis static structural analysis and the LabVIEW system. The cutting power in a cutting process using a milling tool for processing metals provides useful information for understanding the processing, optimization, tool status monitoring, and tool design. Thus, various methods of measuring cutting power have been proposed. The device consists of a strain-gauge-based sensor fitted to a new design force sensing element, which is then placed in a force reduction. The force-sensing element is designed as a symmetrical cross beam with four arms of a rectangular parallel line. Furthermore, data duplication is eliminated by the appropriate setting the strain gauge attachment position and the construction of a suitable Wheatstone full-bridge circuit. This device is intended for use with rotating spindles such as milling tools. Verification and machining tests were performed to determine the static and dynamic characteristics of the tool dynamometer. The verification tests were performed by analyzing the difference between strain data measured by weight and that derived by theoretical calculations. Processing test was performed by attaching a tool dynamometer to the MCT to analyze data generated by the measuring equipment during machining. To maintain high productivity and precision, the system monitors and suppresses process disturbances such as chatter vibration, imbalances, overload, collision, forced vibration due to tool failure, and excessive tool wear; additionally, a tool dynamometer with a high signal-to-noise ratio is provided.

• Korean Journal of Materials Research
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• v.31 no.3
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• pp.156-161
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• 2021

Cr-Si based alloys are not only excellent in corrosion resistance at high temperatures, but also have good wear resistance due to the formation of Cr3Si phase, therefore they are promising as metallic coating materials. Aluminum is often added to Cr-Si alloys to improve the oxidation resistance through which stable alumina surface film is formed. On the other hand, due to the addition of aluminum, various Al-containing phases may be formed and may negatively affect the heat resistance of the Cr-Si-Al alloys, so detailed investigation is required. In this study, two Cr-Si-Al alloys (high-Si & high-Al) were prepared in the form of cast ingots through a vacuum arc melting process and the microstructural changes after high temperature heating process were investigated. In the case of the cast high-Si alloy, a considerable amount of Cr3Si phase was formed, and its hardness was significantly higher than that of the cast high-Al alloy. Also, Al-rich phases (with the high Al/Cr ratio) were not found much compared to the high-Al alloy. Meanwhile, it was observed that the amount of the Al-rich phases reduced by the annealing heat treatment for both alloys. In the case of the high temperature heating at 1,400 ℃, no significant microstructural change was observed in the high Si alloy, but a little more coarse and segregated AlCr phases were found in the high Al alloy compared to the cast state.

• The Research Journal of the Costume Culture
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• v.29 no.6
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• pp.904-921
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• 2021

The aim of this study was to develop a body type suitable for adult men aged from their 20s to their 40s and to present a method of drafting related patterns. To this end, the somatic surface pattern data from previous studies were used. The research method involved drafting torso patterns for each type by setting and distributing the ease to the somatic surface pattern. Appearance evaluation was performed with virtual clothing. Then, the torso pattern for each body type was completed and presented as a draft method. SPSS was used for data analysis in this study. The research results are as follows. Types 1, 2, and 3 were set to 7%, 6%, 5%; 7%, 6%, 4%; and 6.5%, 7%, and 6% for chest, waist, and hip circumference measurements, respectively. The ratio of front to back was 50%:50%, 50%:50%, and 50%:50% of the spare for each body part for Type 1; 70%:30%, 50%:50%, and 60%:40% for Type 2, and 60%:40%, 70%:30%, and 60%:40% for Type 3. A tight-fit torso pattern for each body type suitable for adult males in their 20s to 40s was drafted, which was modified and supplemented through the evaluation of the first and second virtual wear. Considering the practicality of this approach, for generalization of the patterns, the items of the pattern were converted into a drafting method and presented as a draft method.

• The Research Journal of the Costume Culture
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• v.30 no.2
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• pp.281-296
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• 2022

This study is designed to compensate for the lack of children's clothing relics from the early 18th century and to reproduce young upper-class girls' costume as hanbokcontent. The shapes and materials of costumes are based on the record of 『Sukjong-silrok』 in 1701 and the characteristics of adult ladie's costume relics in this period, but reproduced as miniatures of these relics as like Joseon children's clothing of another period. The reproduced costumes are formal wear for 3~4 year-old girls, consisting of yeoui [女衣], long unlined skirts, and lined skirts. Sizes were set at a height ratio of approximately 155:95. Yeoui is sam-hoejang-jeogori using pine pollen-colored damask with a grape-squirrel pattern and a purple damask with flower-treasure pattern. The full length of yeoui is 24.5cm. It has a square-dangko outer collar with square inner collar. The long unlined skirt is a six-width overskirt that is 82cm long, made with lotus patterned sa. The lined skirt is a five-width skirt that is 61.3cm made with flower-treasure patterned red damask and ju. Several long pleats on both sides of these two skirts have been omitted. The result provides meaningful content for children's clothing in the early 18^th century and will be used as costume for an educational trial performance.