• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1994.04c
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• pp.6-6
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• 1994

Har dmaterials such as cemented carbides with or without coated layer, cermets, ceramics and diamond or c-BN high pressure sintered compact are used for cutting tools, wear -resistant parts, rock drilling bits and/or high pressure vessels. These hardmaterials contain not only hard phase, but also second consituent as the element for forming ductile phase and/or sintering aid, and the mechanical properties of each material depend on (1) the amount of the second constituent as well as (2) the grain size of the hard phase. The hardness of each material mainly depends on these two factors. The fracture strength, however, largely depends on other microstructur a1 factors as well as the above two factors. For all hardmaterials, the fracture strength is consider ably affected by (3) the size of microstructur a1 defect which acts as the fracture source. In cemented carbides, the following factors which are generated mainly due to the addition of the second constituent are also important; (4) the variation of the carbon content in the normal phase region free from V-phase and graphite phase, (5) the precipitation of $Co_3$ during heating at about $800^{\circ}C$,(6) the domain size of binder phase, and (7) the formation of ${\beta}$-free layer or Co-rich layer near the surface of sintered compacts. For cemented carbides coated with thin hard substance, the important factors are as follows; (8) the kind of coated substance, (9) the formation of ${\eta}$-phase layer at the interface between coated layer and substrate, (10) the type of residual stress (tension or compression) in the coated layer which depends on the kind of coating method (CVD or PVD), and (11) the properties of the substrate, and (12) the combination, coherency and periodicity of multi-layers. In the lecture, the details of these factors and their effect on the strength will be explained.

• Journal of the Korea Fashion and Costume Design Association
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• v.17 no.4
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• pp.77-90
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• 2015

This study is to designed to provide foundation for knit design which can apply the thickness and flexibility of jacquard knit by analyzing and comparing mechanical properties of 7 types of jacquard (normal jacquard, bird's eye jacquard, floating jacquard, tubular jacquard, ladder's back jacquard, blister jacquard, transfer jacquard) widely used in knit design to achieve the results. The sample was projected by using 7 gauge and SES-122S type computer knitting machine house tooth pattern with two colors were applied to 7 types of jacquard using Acrylic/Wool(30%/70%) $2/50.5^{\prime}s{\times}4ply\;yarn$ by Shimaseiki MFG., Ltd computer knitting machine. The mechanical properties of 7 types of jacquard samples were measured using KES-FB (Kawabata Evaluation System for Fabric, Kata Tech Co. Ltd). HV(Hand Value) and THV (Total Hand Value) were calculated by using the formula of KN-402-KT and KN-301-WINTER respectively. The measurements were evaluated by 0-to-5 rating scale. As result, the floating jacquard was found to have excellent drape, making it suitable for express feminine silhouette with its most flexible and smooth touch. On the other hand, bird's eye jacquard is adequate for a suit jacket and coat regarding its excellent volume and flexibility. Blister jacquard and tubular jacquard are thick, heavy and stiff knit and both are suitable for simple box-style design. Ladder's back jacquard, however, is more appropriate for expressing the design of feminine charm and voluminous design. Based on the result of this study, it is supposed to provide basic information for development of knit industry regarding jacquard knit by designing the creative knit wear with high production efficiency.

• Fashion & Textile Research Journal
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• v.2 no.3
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• pp.220-226
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• 2000

This study was to determine the characteristics of vapor-permeable waterproof finished fabric by the coating method. 4 different kinds of coating fabrics (A : wet, porous, polyurethane, B : dry, no porous, polyurethane, C : shape memory polyurethane and D : dry, porous polyurethane) were used, which were developed recently With this sample, moisture transport rate ($40^{\circ}C$, 45%RH & $40^{\circ}C$, 95%RH), changes of coating side's shape by washing times, water repellency rate, contracted length, qmax, heat conductivity, heat keeping rate, heat keeping rate with cotton, heat keeping rate on humidity temperature and humidity within clothing etc. were checked. And it was done in a climate chamber under $20{\pm}2^{\circ}C$, $65{\pm}5%RH$. The results of this study were as follow; In the moisture vapor transmission of sample B and C increased on high temperature and high humidity while sample A and D decreased, on this condition. Qmax rate had high relation with ground fabric's surface properties and the order was A>C>D>B. Heat conductivity had high relation with thickness and surface properties. Heat keeping rates on sweat condition showed around half percents of heat keeping rates on normal condition, but had no relation with moisture vapor transport rate. Changes of the fabric's properties by washing times were different in accordance with the construction of fabrics and the coating resin. Sample C had tow heat keeping rate on the high temperature and humidity and high heat keeping rate on the low temperature and humidity Moisture transport rate of vapor-permeable waterproof finished fabrics had high relation with the properties of ground fabrics on low humidity condition, but on the high humidity condition, it was highly related with the properties of coating resin.

• Journal of Korean Dental Science
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• v.5 no.1
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• pp.29-36
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• 2012

Purpose: To investigate the effects of anterior guidance (AG) change on the working (WCP) and non-working condylar paths (NWCP), and lower incisor path (LIP) using a splint with flat (FAG) or steep AG (SAG). Materials and Methods: The samples consisted of six young adult women (mean age=$23.5{\pm}3.3$ years). Inclusion criteria were skeletal Class I and normodivergent pattern, normal overbite/overjet, minimal slide from retruded cuspal position to intercuspal position, no temporomandibular disorder signs and symptoms, mutually protected occlusion, and minimal tooth wear. After the values of natural AG (NAG) were obtained as a reference for each patient, two types of splints ($15^{\circ}$ flatter and steeper than NAG) were made. After insertion of the splints with FAG or SAG, the WCP, NWCP, and LIP were recorded five times for each patient using an ultrasonic AQR (SAM, Munich, Germany) and statistical analysis was subsequently performed. Result: NAG exhibited postero-superior movement in the WCP and did not show a noticeable immediate side shift (ISS) or difference between the eccentric (EP) and returning paths (RP) in the NWCP. FAG was associated with an irregular and excessive WCP, an increase in ISS, and a difference between EP and RP in the NWCP. SAG showed minimal WCP movement and a decrease in the extent of difference between EP and RP in the NWCP. LIP showed significant differences in EP and in RP (P<0.001, all; FAG

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.1
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• pp.134-143
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• 1998

Twin Blocks are simple bite-blocks that effectively modify the occlusal inclined plane to induce favorably directed occlusal forces by causing a functional mandibular displacement. These devices use upper and lower bite-blocks that engage on occlusal inclined planes. Twin Blocks use the forces of occlusion as the functional mechanism to correct the malocclusion. To get an excellent result in the treatment by using the Twin Block appliances, proper case selection must be needed. Twin Block treatment is performed in two stages. Twin Blocks are used in the active phase to correct the anteroposterior relationship and establish the correct vertical dimension. Once this phase is accomplished, the Twin Blocks are replaced with an upper Hawley type of appliance with an anterior inclined plane, which is then used to support the corrected position as the posterior teeth settle fully into occlusion. The Twin Block is the most comfortable, the most esthetic ane the most efficient of all the functional appliances. Twin Blocks have many advantages compared to other functional appliances. Patients can wear Twin Blocks 24 hours per day and can eat comfortably with the appliances in place. From the moment Twin Blocks are fitted, the appearance is noticeably improved. There is less interference with normal function. Integration with conventional fixed appliances is simpler than with any other functional appliance. Twin Blocks allow independent control of upper and lower arch width. Appliance design is easily modified for transverse and sigittal arch development. The authors treated Class II malocclusion with Twin Blocks. and the results as follows; 1. Rapid profile improvement was achieved in 2-3 months. 2. There was excellent patient cooperation. 3. Severe overjet and overbite were reduced. 4. Class II molar relationship was changed to Class I.

• Journal of radiological science and technology
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• v.43 no.2
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• pp.87-96
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• 2020

This study examined the hygiene management of ultrasound probes by examining the cleaning tools for hygiene management of ultrasound probes, the presence or absence of wearing glove as a personal protective equipment, and the awareness of ultrasound probe hygiene. Parts 154 questionnaire about people working in the ultrasound room were surveyed and analyzed. The single gel removal tool of the ultrasound probe was most frequently used with a 48.7% cotton towel, and for double gel removal tools, the first gel removal tool was 42.4% cotton towel and the second gel removal tool was used with 57.6% wet tissue. Antimicrobial wipes were the most commonly used drug and instrument used in ultrasound hygiene management at 58.4%. According to the survey of the presence or absence of wearing glove during ultrasound examination, 46.8% were found to be unworn. When examining the intracavity ultrasound, 30.9% of those who do not wear glove and 61.0% of hygiene awareness of ultrasound probes are 'normal'. According to age, ultrasound probe gel removal tool was not significant difference(p>0.05). According to the working organization and the working department, it was significant difference to wearing gloves during ultrasound examination(p<0.05). Therefore, in order to properly sanitize the ultrasound probe, it is considered that a guideline for hygiene management of the ultrasound probe that fits the situation in Korea is necessary, and it is considered that thorough hygiene management training for inspector is necessary for efficient hygiene management of the ultrasound probe.

• Journal of the Korean Home Economics Association
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• v.20 no.4
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• pp.53-67
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• 1982

Physical measurements of 181 Korean elderly women, aged 60 through 79, living in the Seoul area, were taken in 1981 in order to analyze their body types and to study clothing construction according to their body types. The study was composed of 117 items in all; 35 items in measurements, 1 items in Rohrer index, 68 items in physical index to stature and bust girth, and 14 items in proportion, Coefficients of correlation among body dimensions were used. The results from this analysis are as follows: 1) The most significant changes in body dimensions in advanced age were the decrease of bust height and the increase of both abdomen girth and waist girth. 2) Distinct physical changes did not appear until advanced senescence(70~79 years of age). 3) In the three somatotype groups(thin, average, and plump) categorized by their Rohrer index, the dimensions that remained unchanged in senescence were back waist length and front waist length ; the dimensions that varied most significantly in senescence were the waist measurements. 4) As a result of the analysis of coefficients of correlation among the body dimensions of the 3 figure groups categorized by the Rohrer index, the fundamental dimensions for establishing the size of ready-to-wear garments of elderly women were the stature, bust girth and center back length in upper garments. 5) The result of the analysis of physical index and proportion of the 3 figure groups showed that the more plump a figure might be, the ratio of depth to width measurements increased; the back waist height was higher and trunk enlarged. 6) The 9 figure categorized by their Rohrer index and stature showed that the percentage of women in the category of“normal figure”decreased more in advanced senescence than during early senescence. 7) An analysis of variation of the 9 figure groups, the stature and other items for a short and thin figure were the smallest, and for a tall and plump figure, the largest.

• Nuclear Engineering and Technology
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• v.50 no.2
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• pp.223-228
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• 2018

AREVA NP (Courbevoie, Paris, France) is actively developing several enhanced accident-tolerant fuels cladding concepts ranging from near-term evolutionary (Cr-coated zirconium alloy cladding) to long-term revolutionary (SiC/SiC composite cladding) solutions, relying on its worldwide teams and partnerships, with programs and irradiations planned both in Europe and the United States. The most advanced and mature solution is a dense, adherent chromium coating on zirconium alloy cladding, which was initially developed along with the CEA and EDF in the French joint nuclear R&D program. The evaluation of the out-of-pile behavior of the Cr-coated cladding showed excellent results, suggesting enhanced reliability, enhanced operational flexibility, and improved economics in normal operating conditions. For example, because chromium is harder than zirconium, the Cr coating provides the cladding with a significantly improved wear resistance. Furthermore, Cr-coated samples exhibit extremely low corrosion kinetics in autoclave and prevents accelerated corrosion in harsh environments such as in water with 70 ppm Li leading to improved operational flexibility. Finally, AREVA NP has fabricated a physical vapor deposition prototype machine to coat full-length cladding tubes. This machine will be used for the manufacturing of full-length lead test rods in commercial reactors by 2019.

• Tribology and Lubricants
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• v.31 no.2
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• pp.50-55
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• 2015

This study investigates the effects of a pattern of 200 μm dimples in a hexagonal array on tribological characteristics. A textured surface might reduce the friction coefficient and wear caused by third-body abrasion and thus improve the tribological performance. There are three friction conditions based on the Stribeck curve: boundary friction, mixed friction, and fluid friction conditions. In this experiment, we investigate the friction characteristics by carrying out the friction tests at sliding speeds ranging from 0.06 to 0.34 m/s and normal load ranging from 10 to 100 N. We create dimple surfaces for texturing by using the photolithography method. There are three kinds of specimens with different dimple densities ranging from 10% to 30%. The dimple density on the surface area is the one of the important factors affecting friction characteristics. Friction coefficient generally decreases with an increase in the velocity and load, indicating that the lubrication regime changes depending on the load and velocity. The fluid friction regime is fully developed, as indicated by the duty number graph. Fluid friction occurs at a velocity of 0.14-0.26 m/s. The best performance is seen at 10% dimple density and 200 μm dimple circle in the hexagonal array.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.356-356
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• 2010

Tribological behaviors of the hard film on soft substrate system were explored using the hard thin film of diamond-like carbon (DLC) coated the soft polymer of polydimethysiloxane (PDMS). A DLC film with the Young's modulus of 100 GPa was coated on PDMS substrate with Young's modulus of 10 MPa using plasma enhanced chemical vapor deposition (PECVD) technique. The deposition time was varied from 10 sec to 10 min, resulting in nanoscale roughness of wrinkle patterns with the thickness of 20 nm to 510 nm, respectively, at a bias voltage of $400\;V_b$, working pressure 10 mTorr. Nanoscale wrinkle patterns with 20-100 nm in width and 10-30 nm height were formed on DLC coating due to the residual stress in compression and difference in Young's modulus. Nanoscale roughness effect on tribological behaviors was observed by performing a tribo-experiment using the ball-on-disk type tribometer with a steel ball of 6 mm in diameter at the sliding speed of 220 rpm, normal load of 1N and 25% humidity at ambient temperature of $25^{\circ}C$. Friction force were measured with respect to thickness change of coated DLC thin film on PDMS. It was found that with increases the thickness of DLC coating on PDMS, the coefficient of friction decreased by comparison to that of the uncoated PDMS. The wear tracks before and after tribo-test were analyzed using SEM and AFM.