• 한국재료학회지
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• 제18권4호
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• pp.211-217
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• 2008

A $ZrO_2$ coating solution containing $ZrO_2$ photo-catalysis, which is transparent in visible light, was prepared by the hydrolysis of alkoxide, and thin films on the $SiO_2$ glass substrate were formed in a dipcoating method. These thin films were heat-treated at temperatures ranging from $250^{\circ}C-800^{\circ}C$ and their characteristics were subjected to thermal analysis, XRD, spectrometry, SEM, EDS, contact angle measurement, and AFM. Tetragonal $ZrO_2$ phase was found in the thin film heat treated at $450^{\circ}C$, and anatase $TiO_2$ phase was detected in the thin film heat-treated at $600^{\circ}C$ and above. The thickness of the films was approximately 300 nm, and the roughness was 0.66 nm. Thus, the film properties are excellent. The films are super hydrophilic with a contact angle of $4.0^{\circ}$; moreover, they have self-cleaning effect due to the photo catalytic property of anatase $TiO_2$.

• Journal of Photoscience
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• 제9권3호
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• pp.41-43
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• 2002

PDT-mediated cyototoxicity basically depends on the penetrated light-dose into the tumor tissue. This limits the efficiency of PDT to the superficial tumor region typically less than 1 cm. The localized photochemical generation of reactive oxygen species, including singlet oxygen is known to increase expression of assortment of early response genes including heat shock protein. In order to increase PDT cytotoxicity in the treatment of solid tumor, it is desirable to combine PDT with other therapeutic effects. In this preliminary study we evaluated enhanced cytotoxicity from the PDT-mediated expression of thymidine kinase in a transfected tumor cell line. Two types of photo sensitizers, a hematoporphyrin derivative(Photogem, Russia) and aluminium sulphonated phthalocyanine(Photosense, Russia) were used to evaluate the overexpression of hsp-70 in PDT-treated cell. Transient increase of hsp-70 was observed at 6-8 hrs later following irradiation in the photosense-treated cell whereas it was not observed in Photogem-treated cell. In the presence of ganciclovia, transfected cell showed a 17％ increase in the cytotoxicity compared to the PDT only cell.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.953-958
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• 2006

Perimeter zone has been reinforced by active systems, such as fan-coil units, because it causes an increase in heating and cooling loads, dew condensation in winter, or discomfort with cold-draft to residents in buildings, through poor insulation by light-weighed skin due to progressing multi-storied buildings and skyscrapers. However, because these active systems raise Its capacity so that fossil fuel is used as much as they are added, and ultimately, greenhouse effect is urged, we proposed BIPV system functioned as solar collector which can substitute active system. As an early stage, heat balance equation in steady-state by Fortran was used not only for pre-heating effect and electric power capacity during the day in winter, but also for electric power capacity during day in slimmer and sky radiation effect during night in summer. Especially, we should have considered shading on PV, since even a little bit of it makes the efficiency too low for the PV to work. Still, when the flux of pre-heated air was increased to make air-barrier, its temperature was not enough to make it because the speed of heat exchange was too fast to warm up the air, thus the capacity to meet the condition was evaluated, and electric power from PV was made used for it.

• Animal Systematics, Evolution and Diversity
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• 제37권1호
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• pp.9-14
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• 2021

Invasive species threaten global biodiversity as well as human livelihood and much of the global lands are vulnerable to these threats. Numerous freshwater turtles from the northern hemisphere have been introduced in East Asian countries, including the Republic of Korea. Knowing turtle's behavioral ecology is valuable to manage introduced populations and a distinctive behavior is basking for behavioral thermoregulation. To understand the possibility of using basking to enhance trapping, we tested thermotaxis in the river cooter (Pseudemys concinna). Turtles were placed in an aquarium containing heated and non-heated mats under controlled water and air temperature, air humidity and light. We found that P. concinna stayed significantly longer on heated mats than on unheated control mats in 11 out of 18 trials, demonstrating that heat source is a potential attractant for P. concinna. We recommend the use of heat source to bait traps used for population control of invasive freshwater turtles.

• 한국표면공학회지
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• 제47권4호
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• pp.192-197
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• 2014

Red-emitting nitride phosphors recently attracted considerable attention because of their high thermal stability and high color rendering index properties. For excellent phosphor of white light-emitting-diode, ternary nitride phosphor of $Sr/SmSi_5N_8:Eu^{2+}$ with different $Eu^{2+}$ ion concentration were synthesized by solid state reaction method. In this work, red-emitting nitride $Sr/SmSi_5N_8:Eu^{2+}$ phosphor was successfully synthesized by using multi-step high frequency induction heat treatment. The effects of molar ratio of component and experimental conditions on luminescence property of prepared phosphors have been investigated. The structure and luminescence properties of prepared $Sr/SmSi_5N_8:Eu^{2+}$ phosphors were investigated by XRD and photoluminescence spectroscopy. The excitation spectra of $Sr/SmSi_5N_8:Eu^{2+}$ phosphors indicated broad excitation wavelength range of 300 - 550 nm, namely from UV to visible area with distinct enhanced emission peaks. With an increase of $Eu^{2+}$ ion concentration, the peak position of emission in spectra was red-shifted from 613 to 671 nm. After via multi-step heat treatment, prepared phosphor showed excellent luminescence properties, such as high emission intensity and low thermal quenching, better than commercial phosphor of $Y_3Al_5O_{12}:Ce^{3+}$. Using $Eu_2O_3$ as a raw material for $Eu^{2+}$ dopant with nitrogen gas flowing instead of using commercial EuN chemical for $Sr/SmSi_5N_8:Eu^{2+}$ synthesis is one of characteristic of this work.

• 패션비즈니스
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• 제19권4호
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• pp.92-108
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• 2015

This study aimed at developing a down jacket prototype that utilized sunlight as an alternative energy source with no air pollution. The jacket is filled with flexible solar panels and has a heat-generating function and LED function. In this study, three smart down jacket prototypes were developed, and the jacket's capabilities were demonstrated through the thermal effect on the performance test. The typical output voltage of the flexible solar panels was 6.4V. By connecting the 2 solar cell modules in series, the final output voltage was 12.8V. A battery charge regulator module was used the KA 7809 (TO-220) of 9V. Three heating pads were to be inserted into the belly of the jacket as direct thermal heating elements, and the LED module was configured, separated by a flash and an indicator. The smart down jacket was designed to prevent damage to the down pack without the individual devices' interfering with the human body's motion. Because this study provides insulation from extreme cold with a purpose, the jacket was tested for heat insulation properties of non-heating, heating on the back, heating on the abdomen, and heating on both the back and abdomen in a sitting posture in a static state. Thermal property analysis results from examining the average skin temperature, core temperature, and the temperature and humidity within clothing showed, that placing a heating element in one place was more effective than distributing the heating elements in different locations. Heating on the back was the most effective for maintaining optimal skin temperature, core temperature, and humidity, whereas heating on the abdomen was not effective for maintaining optimal skin temperature, core temperature, or humidity within clothing because of the gap between the jacket and the body.

• 한국농공학회지
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• 제22권1호
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• pp.53-66
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• 1980

The research work is concerned with the analytical and experimental studies on the heat transfer phenomenon around the underground concrete digester used for biogas production Systems. A mathematical and computational method was developed to estimate heat losses from underground cylindrical concrete digester used for biogas production systems. To test its feasibility and to evaluate thermal parameters of materials related, the method was applied to six physical model digesters. The cylindrical concrete digester was taken as a physical model, to which the model,atical model of heat balance can be applied. The mathematical model was transformed by means of finite element method and used to analyze temperature distribution with respect to several boundary conditions and design parameters. The design parameters of experimental digesters were selected as; three different sizes 40cm by 80cm, 80cm by 160cm and l00cm by 200cm in diameter and height; two different levels of insulation materials-plain concrete and vermiculite mixing in concrete; and two different types of installation-underground and half-exposed. In order to carry out a particular aim of this study, the liquid within the digester was substituted by water, and its temperature was controlled in five levels-35。 C, 30。 C, 25。 C, 20。C and 15。C; and the ambient air temperature and ground temperature were checked out of the system under natural winter climate conditions. The following results were drawn from the study. 1.The analytical method, by which the estimated values of temperature distribution around a cylindrical digester were obtained, was able to be generally accepted from the comparison of the estimated values with the measured. However, the difference between the estimated and measured temperature had a trend to be considerably increased when the ambient temperature was relatively low. This was mainly related variations of input parameters including the thermal conductivity of soil, applied to the numerical analysis. Consequently, the improvement of these input data for the simulated operation of the numerical analysis is expected as an approach to obtain better refined estimation. 2.The difference between estimated and measured heat losses was shown to have the similar trend to that of temperature distribution discussed above. 3.It was found that a map of isothermal lines drawn from the estimated temperature distribution was very useful for a general observation of the direction and rate of heat transfer within the boundary. From this analysis, it was interpreted that most of heat losses is passed through the triangular section bounded within 45 degrees toward the wall at the bottom edge of the digesten Therefore, any effective insulation should be considered within this region. 4.It was verified by experiment that heat loss per unit volume of liquid was reduced as the size of the digester became larger For instance, at the liquid temperature of 35˚ C, the heat loss per unit volume from the 0. 1m$^3$ digester was 1, 050 Kcal/hr m$^3$, while at for 1. 57m$^3$ digester was 150 Kcal/hr m$^3$. 5.In the light of insulation, the vermiculite concrete was consistently shown to be superior to the plain concrete. At the liquid temperature ranging from 15。 C to 350 C, the reduction of heat loss was ranged from 5% to 25% for the half-exposed digester, while from 10% to 28% for the fully underground digester. 6.In the comparison of heat loss between the half-exposed and underground digesters, the heat loss from the former was fr6m 1,6 to 2, 6 times as much as that from the latter. This leads to the evidence that the underground digester takes advantage of heat conservation during winter.

• Current Photovoltaic Research
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• 제9권4호
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• pp.145-159
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• 2021

Light soaking (LS) stability in polymer solar cells (PSCs) has always been a challenge to achieve due to unstable photoactive layer-electrode interface. Especially, the electron transport layer (ETL) and photoactive layer interface limits the LS stability of PSCs. Herein, we have modified the most commonly used and robust zinc oxide (ZnO) ETL-interface using an organic dye molecule and a co-adsorbent. Power conversion efficiencies have been slightly improved but when these PSCs were subjected to long term LS stability chamber, equipped with heat and humidity (45℃ and 85% relative humidity), an outstanding stability in the case of ZnO/dye+co-adsorbent ETL containing devices have been achieved. The enhanced LS stability occurred due to the suppressed interfacial defects and robust contact between the ZnO and photoactive layer. Current density as well as fill factors have been retained after LS with the modified ETL as compared to un-modified ETL, owing to their higher charge collection efficiencies which originated from higher electron mobilities. Moreover, the existence of less traps (as observed from light intensity-open circuit voltage measurements and dark currents at -2V) are also found to be one of the reasons for enhanced LS stability in the current study. We conclude that the mitigation ETL-surface traps using an organic dye with a co-adsorbent is an effective and robust approach to enhance the LS stability in PSCs.

• 한국세라믹학회지
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• 제42권3호
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• pp.145-149
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• 2005

[ $Eu^{2+}$ ]-activated barium magnesium silicate phosphor, $(Ba,Ca)_{3}MgSi_{2}O_{8}:Eu_{x}$, has been known to emit blue-green light. In this study we report the manufacturing processes for producing either pure green or pure blue light-emitting phosphor from the same composition of $Ba_{2-x}Ca_{2}CaMgSi_{2}O_{8}:Eu_{x}$ (0 < x < 1) by controlling heat treatment conditions. Green light emitting phosphor of $Ba_{1.9}CaMgSi_{2}O_{8}:Eu_{0.1}$ can be produced under the sample preparation condition of highly reducing atmosphere of $23\%\;H_2/77\%\;N_2$, while blue or blue-green light emitting phosphor under reducing atmosphere of $5\~20\%\;H_2\;/\;95\~80\%$ N_2. The green light-emitting phosphors are prepared in two steps: firing at $800\~1000^{\circ}C$ for $2\~5$ h in air then at $1100\~1350^{\circ}C$ for 2-5 h under reducing atmo­sphere $23\%$ $H_2/77\%\;N_2$. The excitation spectrum of the green light-emitting phosphor shows a broadband of $300\~410$ nm. The emission spectrum has a maximum intensity at the wavelength of about 501 nm. The CIE value of green light emission is (0.162, 0.528). The pure blue light-emitting phosphors can be produced using the $Ba{2_x}CaMgSi_{2}O_{8}:Eu_{x}$ by introducing additional firing step at $1150\~1300^{\circ}C$ in air before the final reducing treatment. The XRD analysis shows that the green light-emitting phosphor mainly consisted of $Ba_{1.31}Ca_{0.69}SiO_{4}$ (JCPDS $\#$ 36-1449) and other minor phases i.e., $MgSiO_3$ (JCPDS $\#$ 22-0714) and $Ca_{2}BaMgSi_{2}O_{8}$ (JCPDS $\#$ 31-0128). The blue light-emitting phosphor mainly consisted of $Ca_{2}BaMgSi_{2}O_{8}$ phase.

• 마이크로전자및패키징학회지
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• 제21권1호
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• pp.19-23
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• 2014

LED (Light Emitting Diode) 시장의 발전이 빠르게 이루어지고 있음에 따라 점차 고효율 LED의 필요성이 증가하고 있다. 이에 우리는 Hole Type의 Padless 신 구조 수직형 LED에서, 접촉 전극의 크기와 그 배치가 Chip의 가동 전압에 어떠한 영향을 미치는지 알아보았다. 이를 위하여 LED simulation을 통한 계산과 실제 Chip 제작을 통한 전기적 특성 평가를 하였다. 그 결과, Simulation 을 통하여 n전극의 크기가 커질수록 구동전압이 낮아짐을 확인하였고, N 전극의 형태가 확산됨에 따라서도 구동전압이 낮아짐을 확인하였다. 이러한 추세는 실제 제작한 LED Chip의 측정 결과와 비슷한 경향을 나타내었다.