• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.3
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• pp.285-293
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• 2018

A structure of coacervate affects the adsorption of oil and polymer as a conditioning ingredient. This study aims to elucidate a structural characterization of the coacervate of which is a mixture of alkyl cellulose and guar gum. It is well known that the guar gum supports stiffness to the hair when it is adsorbed on the hair. However, addition of guar gum in the formulation composed of alkyl cellulose tremendously increased flexibility in hair. The stable complex system is induced by an electrostatic force between a head group of anionic surfactant and an quarternary ammonium at the alkyl cellulose, and the affinity of alkyl chain to the oil inside the micelle of surfactant by hydrophobic interactions. Taken together, amount of the coacervate increased oil-delivery upon hair in shampooing and these caused a low bending rigidity and calming on the hair swatch.

• Journal of Korean society of Dental Hygiene
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• v.15 no.4
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• pp.649-659
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• 2015

Objectives: The purpose of the study is to investigate the musculo-skeletal pain prevalence and severity in the dental hygienists based on PRECEDE model. Methods: A self-reported questionnaire was completed by 483 dental hygienists in Gwangju from September 13 to October 12, 2013. Data were analyzed by frequency analysis, chi-square test, t-test, and multiple logistic regression analysis using SPSS 18.0 program. Musculo-skeletal pain severity was classified from 1 to 5 by PRECEDE model. The questionnaire consisted of six questions of the general characteristics of the subjects, one question of musculo-skeletal pain prevalence, one question of body part musculo-skeletal pain prevalence, one question of subjective health status, three questions of activities of daily living, six questions of working environment, one question of musculoskeletal system diseases knowledge, two questions of social support, two questions of education experience and data use method, and five questions of necessity of health education. Results: The prevalence rate of musculo-skeletal pain within a year was 83.9% and 22.8% of the dental hygienists complained of severe pain. The odds ratio of moderate pain severity was 1.99(95% CI, 1.10-3.60) and the odds ratio of unhealthiness was 3.27 (95% CI, 1.35-7.94). The odds ratio of pain severity in those working for 4-6 years was 0.21(95% CI, 0.08-0.57). The odds ratio of pain severity in those practicing 6-10 scaling cases per day was 0.33(95% CI, 0.17-0.65). The odds ratio of pain severity in wrist turning and bending was 3.56(95% CI, 1.19-10.62). Conclusions: The muscolu-skeletal pain severity in the dental hygienists was closely associated with subjective health condition, work duration, the number of scaling practice activity, and a treatment posture. Regular physical checkup for the dental hygienists will improve the musculo-skeletal pain due to scaling practice.

• Journal of the Korean Society for Heat Treatment
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• v.3 no.1
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• pp.34-41
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• 1990

Effects of grain size and cold rolling degree on shape memory ability and transformation temperature were studied in Fe-35% Mn-6% Si shape memory alloy. Md point of the alloy was determined by variation of yield stress with test temperature. The Md point measured in this way was linearly increased with increasing grain size. Shape memory ability of the alloy was decreased with increasing grain size, showing a minimum value at around $63{\mu}m$, and then increased with increasing grain size. From this result, it was concluded that the shape memory ability in the grain size smaller than a critical value is controlled by amount of retained ${\gamma}$ and prior ${\varepsilon}$ phase, but that the shape memory ability in the grain size greater than the critical value is mainly dominated by grain boundary area in unit volume of parent phase. The shape memory ability was decreased with increasing deformation degree. This was because the ${\gamma}$ content being available for the formation of ${\varepsilon}$ martensite during bending was decreased with increasing deformation degree.

• Science of Emotion and Sensibility
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• v.8 no.2
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• pp.117-128
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• 2005

The purpose of this study was to clarify the effects of constituent characteristics and the mechanical properties by KES-FB system on the visual texture images and preference of men's suit fabrics. Twenty different kinds of black fabrics, which were used mainly for the spring and summer men's suits, were selected and the subjective evaluation of the visual texture images was tested. Sixty experts in department of clothing and apparel industries participated in the subjective evaluation. Factor analysis showed visual texture images were classified into 4 categories : 'bulkiness', $'extensibility{\cdot}rapability'$, 'flexibility' and 'smoothness'. All of relationships were established between the mechanical properties and the visual texture images except the relation between 'flexibility' and bending properties. The significant factors affecting preference were 'smoothness', compression energy(WC), fabric count and 'flexibility', As the fabrics had higher value for 'smoothness' and 'flexibility' , and lower ones for compression energy and fabric count, they tended to be more preferred.

• Journal of Korean Society of Steel Construction
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• v.27 no.2
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• pp.169-180
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• 2015

Recently, Seismic performance of the building built in the past is required to review, because the code for seismic design have been reinforced. In 2009, if the revised latest criteria of seismic design is applied, the majority the steel structure of the low-rise concentrically braced system is short of the seismic performance. Also, when the steel braces are subject to compressive load, which causes unstable behavior of the structure. In order to verify the compressive behavior of the reinforced braces, structural performance test was conducted with variables of slenderness ratio and the amount of reinforcement. Therefore, this study suggests restraining the bending buckling of slender H-shaped braces to resist compressive force. In order to verify the compressive behavior of the reinforced braces, structural performance test was conducted with variables of slenderness ratio and the amount of reinforcement.

• Journal of the Korean Ceramic Society
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• v.27 no.4
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• pp.465-472
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• 1990

The effects of Al2O3 and Cr2O3 addition on the mechanical properties and microstructures of Y-TZP ceramics obtained by co-precipitation method of ZrO2＋3m/o Y2O3, following pressureless sintering at 150$0^{\circ}C$ for 2h were investigated. The addition of Al2O3 and Cr2O3 improved the Y-TZP sinterability and the Al2O3 addition showed the better effect on Y-TZP sintering than that of the Cr2O3 addition. The density and microstructure had the better effect on the bending strength of specimen more than stressinduced phase transformation (SIPT) of ZrO2 from tetragonal to monoclinic phase. The hardness of the specimens was found to be depend on the relative density and the fracture toughness of Y-TZP was found to rely on the amount of SIPT. The grian size of Cr2O3-doped Y-TZP was observed to be relatively smaller and had a narrower distribution than that of Al2O3-doped Y-TZP. If decomposition reaction of Cr2O3 can be controlled at high temperatures, it is anticipated that the mechanical properties of Y-TZP can be much improved by the Cr2O3 addition.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.2004-2006
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• 1996

A thermally driven polysilicon micro actuator has been fabricated using surface micromachining techniques. It consists of P-doped polysilicon as a structural layer and TEOS (tetracthylorthosilicate) as a sacrificial layer. The polysilicon was annealed for the relaxation of residual stress which is the main cause to its deformation such as bending and buckling. And the newly developed HF VPE (vapor phase etching) process was also used as an effective release method for the elimination of sacrificial TEOS layer. The thickneas of polysilicon is $2{\mu}m$ and the lengths of active and passive polysilicon cantilevers are $500{\mu}m$ and $260{\mu}m$, respectively. The actuation is incurred by die thermal expansion due to the current flow in the active polysilicon cantilever, which motion is amplified by lever mechanism. The moving distance of polysilicon micro actuator was experimentally conformed as large as $21{\mu}m$ at the input voltage level of 10V and 50Hz square wave. The actuating characteristics are investigated by simulating the phenomena of heat transfer and thermal expansion in the polysilicon layer. The displacement of actuator is analyzed to be proportional to the square of input voltage. These micro actuator technology can be utilized for the fabrication of MEMS (microelectromechanical system) such as micro relay, which requires large displacement or contact force but relatively slow response.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1409-1410
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• 2015

현대기술의 발달로 인해 인간의 삶 중 많은 부분을 기계가 차지하고 있다. 특히 로봇공학 분야는 위험하거나 혹은 매우 정밀함을 요하는 일, 단순반복 등 인간이 기피하거나 하기 어려운 일을 대신 해줌으로서 많은 관심을 받고 있다. 이에 우리는 우리 생활에 가장 깊숙히 들어와 있는 로봇팔분야에 대해 말하고자 한다. 현재 로봇팔은 산업용은 물론, 의료용, 재해용 등 다양한 분야에서 사용되고 있다. 하지만 매우 정밀하고 정확한 작업을 위해 만들어져 있음에도 불구하고, 약간의 충격에도 이상이 생긴다거나, 기기의 이음세 부분의 잦은 회전으로 마모가 발생하게 되고 그에 따라 미세한 오차가 발생한다. 그런 상황을 방지하고자, 우리는 PSD(Position Sensitive Detecter)센서를 이용해 실시간으로 굽힘각을 측정 및 감시하여 보다 정확한 구동을 유도하려 한다. 이는 단순한 로봇팔만이 아닌 휴머노이드나 다른 회전을 이용하는 기기라면 어디든 쉽게 적용 할 수 있을 것이다.

• Journal of the Korean Society of Safety
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• v.30 no.6
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• pp.1-6
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• 2015

The actual condition is that environmental pollution due to the development of various industries has recently become a serious issue. An interest in improving the gas mileage is rising due to an increase in the number of vehicles in the era of high oil price in particular. In order to solve this problem, priority should be given to light-weight design of car body, However, at present, a design method enabling the conventional steel plate to be replaced is direly needed in order to guarantee passengers' safety according to excessive light-weight design of car body. In this study, in order to apply a design method that could realize fuel savings and environmental pollution prevention through an improvement in gas mileage together with meeting the safety requirements for vehicles, it was supposed that CFRP/Al composites member would be used as primary structural member. And to this end, it was intended to obtain optimum design data by experimentally implementing external impulsive load applied to the car body. According to results of impact test of CFRP/Al composites member, a collapsed shape of folding, crack, and bending occurred. So, it was possible to find that energy was observed. And in case of specimen having an angle of $90^{\circ}$ in the outermost layer and stack sequence of $[90^{\circ}{_2}/0^{\circ}2]s$, its collapsed length was shown to be short. Therefore, it was possible to find that the absorbed energy was shown to be higher by 20% or above at the maximum.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.10
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• pp.1327-1336
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• 2001

The structural modes driven by the low wave-number components of smooth elastic wall pressure provide a relatively weak coupling between the flow and the wall motion. If the elastic thin plate has any resonant mode whose wave-number of resonance coincides with $\omega$/U$\sub$c/, the power will be transmitted to those modes of vibration by the flows. We examine the problem in which the elastic thin plate is subject to pressure fluctuations under turbulent boundary layer. Measurements are presented of the frequency spectra of the near- and far-field pressures and radiated sound contributed by the various wave modes of the thin elastic plate. Dispersion equation for wave motions of elastic plate is used to investigate the effect of bending waves of relatively low wave number on radiated sound. The low wave-number motion of elastic plate is observed to have much less influence on the low-frequency energy of wall pressure fluctuations than that of the rediated sound. High amplitude events of the wall pressure are observed to weakly couple with high-frequency energy of radiated sound for case of low tension applied to the plate. The sound source localization is applied to the measurement of radiated sound by using acoustic mirror system.