• Title/Summary/Keyword: preferred temperature

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An Investigation of Preferred Orientation and Microhardness of Nickel-Tin and Tin-Zinc Alloy Electrodeposits on Mild Steel (연강에서의 닉켈-주석과 주석-아연합금 전착층의 우성배향와 미소경도에 관한 연구)

  • Ahn, Deog-Su;Pyun, Su-Il
    • Journal of the Korean institute of surface engineering
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    • v.13 no.3
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    • pp.146-154
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    • 1980
  • The effects of various electrodeposition conditions (deposition temperature and cathode current density) on preferred orientation and microhardness of electrodeposited Ni-Sn and Sn-Zn alloys were studied. At deposition temperatures from 25$^{\circ}$ to 95$^{\circ}C$ and constant cathode current density of 270 and 530 A/$m^2$ Ni-Sn and Sn-Zn were codeposited in chloride-fluoride acid and stannate-cyanide alkaline electrolyte bath respectively. Ni-Sn alloy deposited at temperatures from 25$^{\circ}$ to 35$^{\circ}C$ was composed of single phase of $Ni_3Sn_4$ with 73 wt.% Sn and the one deposited at temperatures from 45$^{\circ}$ to 95$^{\circ}C$ was made of multiphase mixture of NiSn, $Ni_3Sn_2$ and $Ni_3Sn_4$ with nearly equiatomic composition (65.5 wt.% Sn). The random orientation of thermody-namically metastable NiSn phase (hexagonal structure) predominated at deposition temperature range 25$^{\circ}$-45$^{\circ}C$, and the strong (110) preferred orientation was found at 65$^{\circ}$-85$^{\circ}C$ and then disappeared again at 95$^{\circ}C$. The microhardness of Ni-Sn deposits increased with deposition temperature up to 85$^{\circ}C$, and then decreased at constant cathode current density. The preferred orientation and the maximum microhardness were discussed in terms of lattice contractile stress which result from desorption of hydrogen atom absorbed in deposit lattice. The Sn content of Sn-Zn alloy deposits increased with deposition temperature up to 75$^{\circ}C$, and then decreased at constant cathode current density of 530 A/$m^2$. It also decreased with cathode current density up to 530 A/$m^2$, and then increased at constant deposition temperature of 25$^{\circ}C$. Sn-Zn alloy deposits were composed of two-phase mixture of ${beta}$-Sn and Zn. The preferred orientations of ${beta}$-Sn (tetragonal structure) changed with deposition temperature. The microhardness of Sn-Zn deposits decreased with deposition temperature. It also increased with cathode density up to 530 A/$m^2$, and then decreased at constant deposition temperature of 25$^{\circ}C$. The microhardness of Sn-Zn deposits was observed to be determinded more by the Sn content than by the preferred orientation.

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Effects of Substrate Temperature and Sputter Gas on the Physical Characteristics, Chemical Composition and Preferred Orientation of ZnO Thin Films (기판온도 및 스퍼터가스에 따른 ZnO 박막의 우선배향성, 화학조성, 물리적특성 변화)

  • 김병진;조남희
    • Journal of the Korean Ceramic Society
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    • v.34 no.12
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    • pp.1227-1234
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    • 1997
  • ZnO thin films were prepared by rf-magnetron sputter at various conditions. Crystallinity, microstructure, chemical composition, and optical composition, and optical properties of the films were investigated as functions of substrate temperature (R. T.-50$0^{\circ}C$) an sputter gas (O2/Ar=0-50%). ZnO thin films grown at 50$0^{\circ}C$ with sputter gas of pure argon as well as at R. T. with sputter gas of a mixture of argon & oxygen(O2/Ar=2%) exhibit a strong tendency of (002) preferred orientation, compared with a considerable random orientation at the other conditions. The thin films with (002) preferred orientation has a chemical stoichiometry of Zn/O-1.01, a band gap of 3.3eV, and a packing density of 98% respectively.

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Influence of menstrual cycle on preferred clothing and preferred ambient temperature (생리주기가 쾌적착의량과 쾌적온도에 미치는 영향)

  • Jeong, Woon-Seon
    • Journal of the Korean Society of Clothing and Textiles
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    • v.25 no.9
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    • pp.1655-1660
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    • 2001
  • 여성의 생리주기가 행동성 체온조절에 미치는 영향을 관찰하고자, 본 연구에서는 6명의 건강한 여자대 학생을 대상으로 하여 22.5$^{\circ}C$와 55%RH의 환경에서 피험자 스스로가 의복을 선택하는 쾌적의복선택 실험과 피험자 스스로가 온도를 선택하는 쾌적 온도선택 실험을 각각 수행하였다. 평균피부온은 생리주기에 관계없이 쾌적온도선택 실험보다 쾌적의복선택 실험에서 높게 유지되었고, 생리주기에 따른 쾌적착의량과 쾌적온도의 차이는 보이지 않았다. 그러나, 6명의 피험자 중 4명의 피험자가 선택하여 착용한 착의량은 황체기보다 여포기에 더 많았고 (p<0.05), 5명의 피험자가 선택한 쾌적온도 역시 황체기보다 여포기에 평균 1.4$^{\circ}C$ 더 높은 것으로 나타났다 (p<0.01). 이러한 결과는, 피부의 온도를 조절함으로써 여포기보다 황체기에 심부체온을 높게 유지하기 위한 행동성 체온조절반응을 나타낸 것으로 보이나, 보다 명확한 결론을 내리기 위해서는 다양한 환경조건에서 다수의 피험자를 대상으로 하는 후속연구가 지속적으로 수행되어 야 할 것이다.

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Microstructure and Hardness Changes of the CVD-ZrC Film with Different Deposition Temperature (증착온도 변화에 따른 화학증착 ZrC의 미세구조와 경도 변화)

  • Park, Jong-Hoon;Jung, Choong-Hwan;Kim, Weon-Ju;Kim, Do-Jin;Park, Ji-Yeon
    • Journal of the Korean Ceramic Society
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    • v.45 no.9
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    • pp.567-571
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    • 2008
  • The properties of a grown film by the chemical vapor deposition process depend on the deposition temperature because the deposition mechanism of the CVD film is controlled by the deposition temperature. The preferred orientation of the zrC film changed from (111) to (220) or (200) with an increase of the deposition temperature. The grain size of the ZrC film changes from $0.8{\mu}m$ to $2.5{\mu}m$ in the range of 1350 to $1500^{\circ}C$. The hardness of the deposited ZrC film depended on the preferred orientation and the grain size. The hardness of the ZrC film deposited at $1400^{\circ}C$ was 31 GPa.

Exercise Habits and Thermoregulatory Responses of College Students (대학생의 운동습관과 체온조절반응)

  • Jeong, Woon Seon
    • The Korean Journal of Community Living Science
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    • v.26 no.3
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    • pp.589-595
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    • 2015
  • This study examines how exercise habits affect human thermoregulatory responses. A total of 14 healthy male college students participated in this study as subjects: 8 students who exercised regularly (REG) and 6 students who did not (IREG). First, there were no significant differences between REG and IREG in rectal and mean skin temperatures. Second, the general thermal sensation was "slightly warm" at the equilibrium state and "cool" during body cooling in both groups with no significant differences between the two groups. This implies that exercise habits did not affect the subjective thermal sensation under this study's environmental conditions. Third, there were no significant correlations between the preferred temperature and related variables such as rectal and mean skin temperature changes, oxygen uptake, and the general thermal sensation in REG. However, there were significant correlations between the preferred temperature and the mean skin temperature change (p<0.05) and oxygen uptake(p<0.01) in IREG. In sum, these results suggest weak effects of exercise habits on daily life at the individual level. Therefore, future research should verify this study's results under controlled conditions such as cooling intensity and durations.

A Study on the Extraction of Correlated Color Temperature, Illuminance, Control Speed under Controllable LED Lighting in the Kitchen Space (제어가능한 부엌공간 LED조명에서의 색온도, 조도, 제어속도 추출에 관한 연구)

  • Lee, Jin-Sook;Jeong, Chan-Ung;Park, Ji-Young
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.28 no.5
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    • pp.1-14
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    • 2014
  • This study has found out appropriate scopes of correlated color temperature and illuminance value with regard to general diffused lighting and work in the kitchen. It also has presented appropriate photometric quantity control speed for behavioral change with the following results. 1)For general diffused lighting, the appropriate photometric quantity has turned out to be 4,000 to 4,500K in color temperature and illuminance value of 300 to 400lx. And 300lx at 4,500K has proven to be the most comfortable, behavior-appropriate, and preferred pair. 2)As far as appropriate photometric quantity for work is concerned, color temperature of 4,000 to 5,000K and illuminance value of 600 to 800lx are appropriate, while 700lx at 4,500 to 5,000K are the most comfortable, behavior-appropriate, and preferred set. 3)As for appropriate photometric quantity control speed in behavioral change, 3 to 5 seconds has proven the most comfortable, appropriate, and preferred for behavioral change from entry to general areas and 1 to 3 seconds for change from general to work.

Seasonal Comparison in Thermal Comfort of the Human Body (인체 열쾌적성의 계절 비교)

  • Jeong, Woon-Seon
    • The Korean Journal of Community Living Science
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    • v.21 no.4
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    • pp.633-639
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    • 2010
  • This study was carried out to compare human thermoregulatory responses and preferred air temperature by feet immersion between summer and winter in terms of thermal comfort. Five healthy female university students participated in the study as subjects. They experienced feet immersion at $40^{\circ}C$ of water in the climatic chamber of $24^{\circ}C$, 50%RH from 19:30 to 21:00 in the summer and winter, respectively. Rectal temperature gradually decreased and maintained $0.08^{\circ}C$ lower in winter than summer, while mean skin temperature changed $0.4^{\circ}C$ greater in winter than summer(p=0.00). Air temperature selected by each subject for their thermal comfort revealed $0.8^{\circ}C$ higher in summer than winter(p=0.06). The results obtained suggest an increase in human thermoregulation and be used as preliminary data to maintain optimal indoor temperature in summer and winter.

Low Temperature Processing of $SrBi_2Ta_2O_9$ Thin Films

  • Choelhwyi Bae;Lee, Jeon-Kook;Park, Dongkyun;Jung, Hyung-Jin
    • The Korean Journal of Ceramics
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    • v.6 no.2
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    • pp.110-115
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    • 2000
  • $SrBi_2Ta_2O_9$ thin films were deposited at room temperature on the usual (111) oriented Pt bottom electrodes using r.f. magnetron sputtering, and then post-annealed at 650-$800^{\circ}C$ for 30min in oxygen flow. Low temperature processing which shows the preferred oriented SBT thin films was obtained by controlling the sputtering pressure and/or Sr content in target. The orientation and grain growth behavior of SBT thin films were dependent on Sr contents in films. With increasing the excess Bi content up to 50% in SBT thin films, it was possible to lower the onset temperature of grain growth. The c-axis preferred oriented SBT thin films were well-grown under the condition of low post-annealing($650^{\circ}C$) by lowering post-annealing pressure. After $10^{11}$ switching cycles, no polarization degradation was observed in both preferred oriented SBT capacitors.

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Characterization of Electrical Properties of $Ba_{0.65}Sr_{0.35}TiO_3$Thin Films Deposited by RF Magnetron Sputtering (RF 마그네트론 스퍼터링법에 의해 증착된 $Ba_{0.65}Sr_{0.35}TiO_3$ 박막의 전기적 특성 분석)

  • 양기덕;조호진;조해석;김형준
    • Journal of the Korean Ceramic Society
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    • v.32 no.4
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    • pp.441-447
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    • 1995
  • Ba0.65Sr0.35TiO3 (BST) thin films were deposited on Pt/SiO2/Si(100) substrate by rf magnetron sputtering. The substrate temperature changed from 35$0^{\circ}C$ to 55$0^{\circ}C$ and crystalline BST thin films were deposited above 45$0^{\circ}C$. Most of the films had (111) preferred orientation regardless of deposition temperature, but the films changed to (100) preferred orientation as gas pressure increased. The dielectric constant increased with increasing substrate temperature and film thickness, and ranged from 100 to 600 at room temperature. The leakage current increased as substrate temperature increased or as film thickness decreased.

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A theoretical approach to the preferred orientation formation of MgO protection layer using adatom diffusion

  • Yu, Hak-Ki;Lee, Jong-Lam
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.713-715
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    • 2009
  • Preferred orientation of MgO protection layer is controlled via adjusting diffusion of adatom between (111) plane with highest neighbor atoms and (200) plane with lowest neighbor atoms. The diffusion of adatom could be modulated by the factors such as substrate temperature, deposition rate, and extra energy applied on adatom like ion beam energy.

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