• 한국치위생학회지
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• 제15권3호
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• pp.539-546
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• 2015

Objectives: The purpose of the study is to investigate the impact of working environment on the subjective health symptoms in the dental hygienists. Methods: The subjects were 220 dental hygienists in Gwangju and Jeonnam. A self-reported questionnaire was completed from September 9 to 22, 2012. The questionnaire was adapted and modified from building symptom index of workers in large buildings by O. The questionnaire consisted of eight questions of the general characteristics of the subjects, 19 questions of working environment and job satisfaction, nine questions of working environment characteristics, and six questions of subjective health symptoms. The questionnaire was measured by Likert 4 scale. Cronbach's alpha in this study was 0.826. Except incomplete answers, 192 data were analyzed using SPSS 19.0 program including t-test, ANOVA, and multiple regression. Results: The health symptoms were statistically and significantly different in glasses wearer and contact lens wearer, working hour satisfaction, and indoor environment(p<0.05). The subjective health symptoms were statistically different from the salary satisfaction, human relations satisfaction, office air environment, indoor environmental awareness score(p<0.05). Conclusions: It is necessary to improve the pleasant indoor working environment by providing the efficient working environment for the health care providers.

• Tribology and Lubricants
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• 제30권5호
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• pp.247-255
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• 2014

Charged polymer chains, i.e., polyelectrolytes, are known to show superior aqueous lubricating properties compared to those of neutral polymer chains, especially in brush conformation. This is primarily because of the incorporation of a large amount of counterions within the polymer layers and the consequently increased osmotic pressure. However, this effect is active only when the polymer chains remain immobilized even under tribostress, which is not realistic for high-contact pressure tribological applications, especially when they are irreversibly immobilized on tribopair surfaces. In contrast, with free polymers, which can be included as surface-active additives in the base lubricant (water), long-term lubricating performance based on "self-healing" properties is readily expected. In order to assess whether the superior aqueous lubricating properties of polyelectrolyte chains are valid for free polymers too, this study reviews recent studies on the tribological properties of many charged biopolymer and synthetic copolymers at a nonpolar, hydrophobic interface. In contrast to the irreversibly immobilized polyelectrolyte chains, free polyelectrolyte chains show inferior aqueous lubricating properties compared to their neutral counterparts owing to charge accumulation and the consequently impeded surface adsorption on the nonpolar surface. Nevertheless, bovine submaxillary mucin (BSM), a representative biopolymer, shows a sufficiently effective surface adsorption and aqueous lubricating capabilities even at neutral pH without losing the polyanionic characteristics.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.118-118
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• 1999

CVD방법에 의한 TiN 박막 형성에 있어서 ICP-CVD 방법이 대두되고 있다. 이것은 precursor에 대한 radical 형성, 식각된 패턴에서 양 벽의 self-shadowing 효과, 낮은 tress등으로 dense 한 박막을 얻을 수 있기 때문이다. TiN 박막은 Si 기판의 온도를 상온에서 50$0^{\circ}C$까지 유지하면서 TEMAT의 유량을 5-20sccm으로 변화시키면서 증착하였다. 증착 후 TiN 박막의 결정화에 따른 열처리는 Ar과 N2-가스분위기에서 in-situ로 증착하였다. 증착 후 TiN 박막증착 조건수립에 따른 플라즈마 특성진단은 전자의 온도와 밀도, 평균 전자밀도, 이온 에너지 분포, radical 분포, negative 이온분포 등으로 측정하였다. 플라즈마 변수에 따른 TiN 박막의 결정성과 상 변화는 XRD로 분석하였고, 조성비 및 TiN 박막의 원소화학적 상태, 결합에너지, 각 상에 따른 결합 에너지 천이정도, 초기 형성과정 및 반응기구 등은 RBS와 XPS로 조사하였다. TiN 박막의 표면상태, morphology 거칠기, TiN/Si(100)구조에서 계면상태 등은 SEM, AFM, 그리고 HRTEM으로 분석하였다. TiN 구조 박막의 비저항, carrier concentration 그리고 mobility 측정은 박막의 표면이 균일하고 bls-홀이 없는 것으로 하여 4-point probe 방법으로 측정하였다. 이들 분석으로부터 ICP-CVD 방법에 의하여 형성된 TiN 박막이 초고집적 반도체 소자의 contact barrier layer로서의 적용 가능성을 평가하였다.

• 한국수소및신에너지학회논문집
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• 제25권2호
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• pp.145-150
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• 2014

This study investigates the preparation of anti-reflective (AR) coating film to improve the efficiency of solar cell. The AR coating film was successfully obtained by dip-coating with AR coatings prepared by sol-gel method. Fluoroalkylsilane was additionally introduced into the coatings to give the self-cleaning effect of AR coating film. We performed the abrasion test, pencil scratch hardness test and cross-cut test to identify the mechanical strength of AR coating film. As the results, the transmittance of AR coating films with 9.07, 18.13 and 27.20 of IPA/MTMS molar ratios were 93.1, 93.6 and 95.3%, respectively. The water contact angle and transmittance of AR coating film increased by the introduction of hydrophobicity. The prepared AR coating film shows the high level of abrasion, hardness and adhesion. The IPA/MTMS molar ratio of 27.20 and the withdrawing speed range of 0.20 ~ 0.28cm/sec are the optimal coating condition in terms of the transmittance and mechanical strength of AR coating film.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.2102-2103
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• 2008

The major causes of electrical fire are classified to short circuit fault, overload fault, electric leakage and electric contact failure. The occurrence factor of the fire is electric arc or spark accompanied with electrical faults. Residual Current Protective Device(RCD) of high sensitivity type used at low voltage wiring cuts off earth leakage and overload, but the RCD can't cut off electric arc or spark to be a major factor of electrical fire. As the RCDs which are applied low voltage distribution panel are prescribed to rated breaking time about 30[ms](KS C 4613), the RCDs can't perceive to the periodic electric arc or spark of more short wavelength level. To be improved on such problem, this paper is proposed to a electrical fire disaster prevention device(EFDPD) for a RCD trip or a self circuit-breaking function on electric arc or spark due to electrical fire. Some experimental results of the proposed apparatus is confirmed to the validity of the analytical results.

• Child Health Nursing Research
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• 제13권2호
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• pp.157-165
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• 2007

Purpose: This study was done to investigate internet addiction, sexual attitudes and gender egalitarianism in middle school students, and to identify the differences of sexual attitude and gender egalitarianism according to the level of internet addiction. Method: The participants were 344 students from two middle schools in Seoul. Data were collected through self-report questionnaires which included an internet addiction test, a sexual attitude scale, and a Korean gender egalitarianism scale for adolescents. The data were analyzed using the SPSS program. Results: Of the students, 63.1% reported being average on-line users, 33.4%, heavy on-line users, and 3.5%, internet addicted. Sexual attitudes and gender egalitarianism of average on-line users were different from those addicted to the internet. Internet addiction, sexual attitudes and gender egalitarianism of students were different according to general characteristics, time spent on-line, and exposure and contact to cyber obscenities. Conclusion: Sexual attitudes and gender egalitarianism in middle school students were influenced by internet addiction. Therefore nursing interventions to prevent and manage internet addiction need to be developed and provided to middle school students. Also a variety of programs for teaching sexuality to adolescents should be developed.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 춘계종합학술대회
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• pp.255-259
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• 2001

대부분의 전자계산실무 교과 학습 관련 사이트들이 Text 위주의 나열식 학습평가가 대부분이나 본 논문에서는 빠른 속도로 출현하는 새로운 응용 프로그램의 활용을 필요로 하는 상업학교의 전자계산실무 교과목에 적용되는 학습평가를 웹을 기반으로 하여 이론과 실습을 교실에서 교사와 학생이 같이 수업을 하는 것처럼 WWW에서 애니메이션 기법을 이용하여 텍스트와 시각적, 청각적 기능을 포함한 자기주도적인 학습과 이전의 선발이나 배치의 목적으로 사용하기 위해 학습 결과를 양적으로만 측정해 온 것을 개개인의 특성을 고려한 평가 방법인 수준별, 개별화된 질적 평가가 가능하도록 설계 및 구현하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.969-974
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• 2001

Circular cylindrical tubes are widely used in structures such as vehicles and aircraft structures, where light weight and high compressive/bending/torsional load carrying capacity are required. When axially compressed, relatively thick circular cylindrical tubes deform in a so-called ring mode. Each ring develops and completely collapses one by one until the entire length of the tube collapses. During the collapse process the tube absorbs a large amount of energy. Like honey-comb structures, circular cylindrical tubes are light weighted, are capable of high axial compressive load, and absorb a large amount of energy before being completely collapsed. In this report, the subject of axial plastic buckling of circular cylindrical tubes was reviewed first. Then, the axial collapse process of the tubes in a so-called ring mode was studied both experimentally and numerically. In the experiment, steel tubes were axially compressed slowly until they were completely collapsed. Fixed boundary condition was provided. Numerical study involves axisymmetric, elastic-plastic, large deflection, self-contact mechanisms. The measured and calculated results were presented and compared with each other. The purpose of the study was to evaluate the load carrying capacity and the energy absorbing capacity of the tube.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.357.1-357.1
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• 2014

Superhydrophobic WOx nanowire (NW) arrays were fabricated using a thermal evaporation and surface chemistry modification methods by self-assembled monolayer (SAM). As-prepared non-wetting WOx NWs surface shows water contact angle of $163.2^{\circ}$ and has reliable stability in underwater conditions. Hence the superhydrophobic WOx NWs surface exhibits silvery surface by total reflection of water layer and air interlayer. The stability analysus of underwater superhydrophobicity of WOx NWs arrays was conducted by changing hydrostatic pressure and surface energy of WOx NWs arrays. The stability of superhydrophobicity in underwater conditions decreased exponentially as hydrostatic pressure applied to the substrates increased3. In addition, as surface energy decreased, the underwater stability of superhydrophobic surface increased sharply. Specifically, sueprhydrophobic stability increased exponentially as surface energy of WOx NWs arrays was decreased. Based on these results, the models for explaining tendencies of superhydrophobic stability underwater resulting from hydrostatic pressure and surface energy were designed. The combination of fugacity and Laplace pressure explained this exponential decay of stability according to hydrostatic pressure and surface energy. This study on fabrication and modeling of underwater stability of superhydrophobic W18O49 NW arrays will help in designing highly stable superhydrophobic surfaces and broadening fields of superhydrophobic applications even submerged underwater.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.595-596
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• 2006

The flexible organic thin film transistor (OTFT) array to use as a switching device for an organic light emitting diode (OLED) was designed and fabricated in the microcontact printing and low-temperature processes. The gate, source, and drain electrode patterns of OTFT were fabricated by microcontact printing which is high-resolution lithography technology using polydimethylsiloxane(PDMS) stamp. The OTFT array with dielectric layer and organic active semiconductor layers formed at room temperature or at a temperature tower than $40^{\circ}C$. The microcontact printing process using SAM(self-assembled monolayer) and PDMS stamp made it possible to fabricate OTFT arrays with channel lengths down to even nano size, and reduced the procedure by 10 steps compared with photolithography. Since the process was done in low temperature, there was no pattern transformation and bending problem appeared. It was possible to increase close packing of molecules by SAM, to improve electric field mobility, to decrease contact resistance, and to reduce threshold voltage by using a big dielecric.