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최과 교정용 스테인리스 강 선재의 신선 가공법이 내식성에 미치는 영향
고영무,모웅남,최한철 大韓齒科器材學會 2003 대한치과재료학회지 Vol.30 No.1
The dental orthodontic wire requires good mechanical properties, such as elastic strength, combined with a high resistance to corrosion. For increasing elastic strength and delaying onset of stress corrosion cracking, drawing methods(one-step and two-step drawing) have been used in this study to extend service life of metal components, However, there is no information on the electrochemical corrosion behavior of drawn wires for orthodontics. To increase elastic strength, good corrosion resistance, and biocompatibility, the electrochemical characteristics of drawn wire have been researched by field emission scanning microscope and potentiodynamic method in 0.9% NaCl solution. The one-step drawn wire showed the formation of rough surface. The hardness and tensile strength of two-step drawn wire increased. Electrochemical measurements showed that, in the case of two-step drawn wire, the corrosion resistance and pitting potential increased compared with two-step drawn wire due to the drawing induced small surface roughness, such as scratch, whereas passivation and active current density decreased as the reduction in area for drawing increased.
최한철,고영무,모웅남 大韓齒科器材學會 2003 대한치과재료학회지 Vol.30 No.3
The first factor to decide the success of dental implantation is sufficient, osseointegration between implant fixture and its surrounding bone tissue. Thus many studies about this have been under actively. In recent, one of them is to increase the roughness of the surface of an implant fixture by treating the surface of an implant fixture in various ways, increase the contact area between an implant fixture and its surrounding bone tissue and so induce a sufficient osseointegration between them. The roughness of the surface on an implant fixture can be increased by coating the smooth surface of an implant fixture with hydroxyapatite or titanium particles or by treating the surface with acid. But these ways can cause the failure of implantation in the long run due to the separatation of coated particles from an implant fixture and sometime; can't attain the sufficient osseointegration because of emitting ion into the surrounding bone tissue. To develop dental implant materials, fabrication and physical properties of sintered stainless steel have studied using hardness tester, tensile tester, SEM, TEM, EPMA, EDX. Stainless steel compacts containing Cu (2-10 wt%) were prepared either by electroless Cu-plating method which result in the increased homogenization in alloying powder or by Cu-elemental powder addition method on the stainless steel powder Experimental investigation foucusing on mechanical property was performed for Cu-added samples to study the effects of Cu content, electroless Cu-plating method, and Cu-elemental powder addition method on the surface characteristics of sintered stainless steel in Mo and Cu in sintered stainless steel on the mechanical behaviors. Microstructural characterization revealed that Cu-addition by electroless Cu-plating method resulted in less porous material compared that prepared by Cu-elemental powder addition method. Since Cu is blown to be effective in reducing the precipitation of chromium carbide at sensitization temperature, Cr concentration in electroless Cu-plating method was uniformly distributed in the grain boundary and in the matrix. The sintered density in electroless Cu-plating method increased with reducing porosity as a result of the Cu-uniform distribution due to electroless Cu plating during the sintering process. The amount of Cu added in the sintered stainless steel affected significantly tensile strength which increased with 4 wt% Cu and decreased with more than 7 wt% Cu.
師範系 體育敎育科 志望生의 一般運動能力檢査 基準値 設定에 關한 硏究
梁點紅,高基俊,黃喆文,金泰運,金重雄,白永鎬,表內淑,黃太相,徐國雄 釜山大學校 附設 體育科學硏究所 1989 體育科學硏究所 論文集 Vol.5 No.-
This study was analyzed the validity and the reliability of evaluation norm. which was used in choosing and grading events of the General Motor Ability Test. The General Motor Ability Test has been done for applicants for entrance to the department of physical education, college of education, Pusan National University. The subjects of this study were 433 applicants(men :387, women :46) for three years. They were tested in seven events : 1) 100m Dash, 2) 1500m Run(man), 800m Run (woman), 3) Throwing Hand-Ball, 4) Broad Jump, 5) Chinning(man), Flexed-Arm Hang(woman), 6) Zig-Zag Run, 7) Trunk Flexion. The results could be summerized as follows ; 1. In 100m Dash, 1500m Run, and Throwing Hand-Ball, man's average records were shown normal distribution which was inclined toward low ll grade. Therefore, the interval size of those three events must be regulated to lower. 2. Average records of Broad Jump in man were distributed into high (1) grade. So, the interval size must be adjusted to higher. 3. In Chinning, Zig-Zag Run, ad Trunk Flexion, man's average records were shawn normal distribution, and the interval size was similar to present records. 4. For woman, it was impossible to analyze correctly in all seven events because of the small number of subjects. So, it was for the sake of the reference. 5. The record of applicants for three years were operated to the variable quantity analysis. And the restults were these ; 100m Dash was F=3.0865(p<0.05), Chinning F=3.9309(p<0.05), Broad Jump F=14.7338(p<0.001), Throwing Hand-Ball F=4.9716(p<0.01), and Zig-Zag Run F=6.8297(p<0.001). Then, it was shown statistical meaningful difference in three groups. 6. In investigating the validity in choosing seven events, it was concluded that the events have been chosen reasonably. Because all events except for 100m Dash, and Zig-Zag Run in man were independent. From the analysis of the General Motor Ability Test, we could realized the necessity of regulating the standard and the interval size in several events. Then, we proposed the new evaluation norm which was suitable to present situation.
Cheol Woong Ko,Deok Yeon Cho,Yeong Chan Kwak,Keyoung Jin Chun,Jin Kim,Ik Soo Son 대한인간공학회 2011 대한인간공학회 학술대회논문집 Vol.2011 No.5
In order to obtain the design information necessary to develop a lifting module installed in a shower carrier for indoor movement, this study performed lifting tests by setting five types of speed patterns. By measuring the contact force, the maximum contact pressure, and the heart rate through the subjects, this study could quantitatively obtain the lifting speed pattern with less rapid change. In addition, sensibility tests were performed to investigate the effects to the subjects. From this study, it is considered that an optimal design process for a lifting module was proposed, and it is expected that a lifting module will be developed that can provide more convenience to the users
Cheol Woong Ko,Deok Yeon Cho,Tae Soo Bae 대한인간공학회 2013 大韓人間工學會誌 Vol.32 No.5
Objective: The objective of this study was to investigate the effects of drive-assisting system in a shower carrier on the upper body muscle activities of caregivers through drivability tests. Background: In care facilities, one of the major ADL(Activities of Daily Living) factors is bathing/showering. Recently, bath/shower-assisting equipment is actively being introduced in care facilities to reduce caregivers" muscle burden. In particular, it is desirable to utilize a shower carrier equipped with drive-assisting system to effectively care for the elderly. However, there were few systematic studies on the relationship between muscle activities and drive-assisting speeds. Method: For the drivability tests to study the effects on the muscle activities according to the drive-assisting speeds(corresponding drive-voltages: 0.0V, 2.0V, 2.1V, 2.3V), 6 females in their 40s(43±4yrs, 157±5cm, and 54.5±1.5kg) were selected. To measure muscle activities of caregivers through drivability tests, 7 muscles in the upper body(TM/Trapezius Muscle, DM/Deltoid Muscle, BBM/Biceps Brachii Muscle, TBM/Triceps Brachii Muscle, ECRLM/Extensor Carpi Radialis Longus Muscle, FCUM/Flexor Carpi Ulnaris Muscle, and ESM/Erector Spinae Muscle) were selected. Results: In the TM, muscle activities were decreased as 21% compared to 0.0V, when drive-voltage 2.0V was applied, as 57% by 2.1V, and 62% by 2.3V(p<0.05), whereas 40%, 56%, and 69% of muscles activities were decreased respectively from the DM(p<0.05). Also, from the UL(BBM+TBM+ECRLM+FCUM), muscle activities were decreased by 17% with 2.0V as against 0.0V, by 47% with 2.1V, and 52% with 2.3V, whereas decreases in muscle activities from the ESM were found by 20%, 34%, and 42% respectively by 2.0V, 2.1V, and 2.3V(p<0.05). Conclusion: The muscle activities were decreased in the order of the DM, TM, ESM, and UL. As muscle activities were remarkably reduced as drive voltage were increased, it was expected to reduce the upper body muscle burden on the caregivers when using shower carriers equipped with driving-assist system. Applications: The results from this study can be applied for the development of a shower carrier including other equipment to possibly reduce the muscle burden of the caregivers.
Cheol Woong Ko,Deok Yeon Cho,Keyoung Jin Chun 대한인간공학회 2011 대한인간공학회 학술대회논문집 Vol.2011 No.5
In this study, a new mattress prototype designed with Korean body morphological information was fabricated and used to measure human body pressure. Korean body skin data were obtained from the MRI images of Korean adult and the elderly using LATEX mattress to secure the body morphological information. It is found that the values of maximum body pressure of subjects from a newly designed mattress prototype were much lower than those from a flat type mattress. From the result, it is considered that the newly proposed mattress can effectively distribute human body pressure and can provide more convenience to the users.
Ko, Il-Won,Kim, Kyoung-Woong,Lee, Cheol-Hyo,Lee, Kwang-Pyo Korean Society for Biotechnology and Bioengineerin 2007 Biotechnology and Bioprocess Engineering Vol.12 No.5
The biodegradation rate of petroleum hydrocarbon-contaminated soil was evaluated by the effect of temperature variation through bioaugmentation and biostimulation. In this study, biokinetics of batch-, pilot-, and field-scale biodegradation were performed by the optimization of enhanced biodegradation, minimizing the inhibitory effects of seasonal variations such as the rainy and cold winter seasons. From the relationship between remedial timescale and initial concentration, the biokinetic isolines of the biodegradation were smaller in the winter than those in the other seasons. The scale-up of biodegradation process led to enhance its activation energy, and then the field-scale remedial action should be performed in the way to lower the activation energy from the chemical diffusion and microbial activation. Therefore, a remedial or field worker can obtain the remedial timescale from the given apparent data of biokinetics with respect to initial TPH concentration only after the simple remedial investigation.