• 한국표면공학회지
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• 제56권4호
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• pp.233-242
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• 2023

In recent years, energy-management studies in buildings have proven useful for energy savings. Typically, during heating and cooling, the energy from a given building is lost through its windows. Generally, to block the entry of ultraviolet (UV) and infrared (IR) rays, thin films of deposited metals or metal oxides are used, and the blocking of UV and IR rays by these thin films depends on the materials deposited on them. Therefore, by controlling the thicknesses and densities of the thin films, improving the transmittance of visible light and the blocking of heat rays such as UV and IR may be possible. Such improvements can be realized not only by changing the two-dimensional thin films but also by altering the zero-dimensional (0-D) nanostructures deposited on the films. In this study, 0-D nanoparticles were synthesized using a sol -gel procedure. The synthesized nanoparticles were deposited as deep coatings on polymer and glass substrates. Through spectral analysis in the UV-visible (vis) region, thin-film layers of deposited zinc oxide nanoparticles blocked >95 % of UV rays. For high transmittance in the visible-light region and low transmittance in the IR and UV regions, hybrid multiple layers of silica nanoparticles, zinc oxide particles, and fluorine-doped tin oxide nanoparticles were formed on glass and polymer substrates. Spectrophotometry in the UV-vis-near-IR regions revealed that the substrates prevented heat loss well. The glass and polymer substrates achieved transmittance values of 80 % in the visible-light region, 50 % to 60 % in the IR region, and 90 % in the UV region.

• 천문학회보
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• 제46권2호
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• pp.66.3-67
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• 2021

Low-mass stars form by the gravitational collapse of dense molecular cores. Observations and theories of low-mass protostars both suggest that accretion bursts happen in timescales of ~100 years with high accretion rates, so called episodic accretion. One mechanism that triggers accretion bursts is infalling fragments from the outer disk. Such fragmentation happens when the disk is massive enough, preferentially activated during the embedded phase of star formation (Class 0 and I). Most observations and models focus on the gas structure of the protostars undergoing episodic accretion. However, the dust and ice composition are poorly understood, but crucial to the chemical evolution through thermal and energetic processing via accretion burst. During the burst phase, the surrounding material is heated up, and the chemical compositions of gas and ice in the disk and envelope are altered by sublimation of icy molecules from grain surfaces. Such alterations leave imprints in the ice composition even when the temperature returns to the pre-burst level. Thus, chemical compositions of gas and ice retain the history of past bursts. Infrared spectral observations of the Spitzer and AKARI revealed a signature caused by substantial heating, toward many embedded protostars at the quiescent phase. We present the AKARI IRC 2.5-5.0 ㎛ spectra for embedded protostars to trace down the characteristics of accretion burst across the evolutionary stages. The ice compositions obtained from the absorption features therein are used as a clock to measure the timescale after the burst event, comparing the analyses of the gas component that traced the burst frequency using the different refreeze-out timescales. We discuss ice abundances, whose chemical change has been carved in the icy mantle, during the different timescales after the burst ends.

• Macromolecular Research
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• 제14권4호
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• pp.408-415
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• 2006

Temperature-dependent, wide-angle, x-ray diffraction (WAXD) patterns and infrared (IR) spectra were measured for biodegradable poly(3-hydroxybutyrate) (PHB) and its copolymers, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) P(HB-co-HHx) (HHx=2.5, 3.4, 10.5, and 12 mol%), in order to explore their crystal and lamellar structure and their pattern of C-H...O=C hydrogen bonding. The WAXD patterns showed that the P(HB-co-HHx) copolymers have the same orthorhombic system as PHB. It was found from the temperature-dependent WAXD measurements of PHB and P(HB-co-HHx) that the a lattice parameter is more enlarged than the b lattice parameter during heating and that only the a lattice parameter shows reversibility during both heating and cooling processes. These observations suggest that an interaction occurs along the a axis in PHB and P(HB-co-HHx). This interaction seems to be due to an intermolecular C-H...O=C hydrogen bonding between the C=O group in one helical structure and the $CH_3$ group in the other helical structure. The x-ray crystallographic data of PHB showed that the distance between the O atom of the C=O group in one helical structure and the H atom of one of the three C-H bonds of the $CH_3$ group in the other helix structure is $2.63{\AA}$, which is significantly shorter than the sum of the van der Waals separation ($2.72{\AA}$). This result and the appearance of the $CH_3$ asymmetric stretching band at $3009 cm^{-1}$ suggest that there is a C-H...O=C hydrogen bond between the C=O group and the $CH_3$ group in PHB and P(HB-co-HHx). The temperature-dependent WAXD and IR measurements revealed that the crystallinity of P(HB-co-HHx) (HHx =10.5 and 12 mol%) decreases gradually from a fairly low temperature, while that of PHB and P(HB-co-HHx) (HHx = 2.5 and 3.5 mol%) remains almost unchanged until just below their melting temperatures. It was also shown from our studies that the weakening of the C-H...O = C interaction starts from just above room temperature and proceeds gradually increasing temperature. It seems that the C-H...O=C hydrogen bonding stabilizes the chain holding in the lamellar structure and affects the thermal behaviour of PHB and its copolymers.

• 대한원격탐사학회지
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• 제38권6_2호
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• pp.1607-1622
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• 2022

본 연구의 목적은 도시폭염 저감을 위한 기법인 쿨루프를 연구지역에 적용하여 토지피복 객체 간 지표 온도와 흡수일사 간 공간적 상관관계 분석으로 실질적 효과 파악을 목적으로 한다. 이를 위해 실제 쿨루프가 적용된 경상남도 김해시 장유무계동 인근을 연구지역으로 선정하였으며, 드론 DJI Matrice 300 RTK에 열적외 영역센서 FLIR Vue Pro R, 가시광선 영역센서 H20T와 다중분광영역 센서인 Micasense Red-Edge를 활용하여 계측하였다. 계측 일정은 2021년 7월 27일 아침 7시 15분부터 약 1시간 30분 간격으로 총 9장의 열지도와 동일 시간대의 흡수일사 분포도, 쿨루프(113개) 및 일반옥상(367개) 지붕 객체를 추출하였다. 흡수일사 분포도는 ArcGIS의 3D 분석 기능인 Solar Radiation Analysis Tool을 통해 산출한 전천일사 분포도에 Micasense Red Edge를 통해 촬영한 Blue, Green Red, Near Infrared, Red Edge Range 영역대 센서의 조합을 통해 구축한 연구 지역의 알베도 값을 반영하여 구축한다. 전술된 자료를 기반으로 일반옥상과 쿨루프 지붕 객체별 지표온도와 흡수일사 간 Pearson 상관계수를 산출하였다. 분석 결과 일 평균 기준 일반옥상 0.550, 쿨루프 0.387의 상관계수 값을 나타내고 있었다. 하지만, 시간대별 상관성의 변화를 파악한 결과 분석일 기준 태양고도가 높은 시기인 11시 30분과 13시의 경우 일반옥상과 쿨루프 간 상관계수의 차이는 0.022, 0.024 값을 보여 유사한 상관성을 보이고 있다. 그 외 시간대는 일반옥상의 상관계수 값이 쿨루프 보다 약 0.1 이상 높은 값을 보이고 있다. 본 연구는 드론을 통해 취득한 고해상도 영상을 활용하여 쿨루프의 실질적 일사차단 영향의 가능성을 대조군이 되는 일반 옥상과의 상관성 비교를 통해 파악한 사례 연구이다. 향후 본 연구 결과를 기반으로 효율적인 도시열섬 저감기법 적용이 가능할 것으로 사료된다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.58.1-58.1
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• 2010

In solar cell module manufacturing, single solar cells has to be joined electrically to strings. Copper stripes coated with tin-silver-copper alloy are joined on screen printed silver of solar cells which is called busbar. The bus bar collects the electrons generated in solar cell and it is connected to the next cell in the conventional module manufacturing by a metal stringer using conventional hot air or infrared lamp soldering systems. For thin solar cells, both soldering methods have disadvantages, which heats up the whole cell to high temperatures. Because of the different thermal expansion coefficient, mechanical stresses are induced in the solar cell. Recently, the trend of solar cell is toward thinner thickness below 180um and thus the risk of breakage of solar cells is increasing. This has led to the demand for new joining processes with high productivity and reduced error rates. In our project, we have developed a new method to solder solar cells with a laser heating source. The soldering process using diode laser with wavelength of 980nm was examined. The diode laser used has a maximum power of 60W and a scanner system is used to solder dimension of 6" solar cell and the beam travel speed is optimized. For clamping copper stripe to solar cell, zirconia(ZrO)coated iron pin-spring system is used to clamp both joining parts during a scanner system is traveled. The hot plate temperature that solar cell is positioned during lasersoldering process is optimized. Also, conventional solder joints after $180^{\circ}C$ peel tests are compared to the laser soldering methods. Microstructures in welded zone shows that the diffusion zone between solar cell and metal stripes is better formed than inIR soldering method. It is analyzed that the laser solder joints show no damages to the silicon wafer and no cracks beneath the contact. Peel strength between 4N and 5N are measured, with much shorter joining time than IR solder joints and it is shown that the use of laser soldering reduced the degree of bending of solar cell much less than IR soldering.

• 천문학논총
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• 제32권1호
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• pp.201-203
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• 2017

There exists strong evidence supporting the co-evolution of central supermassive black holes and their host galaxies; however it is still under debate how such a relation comes about and whether it is relevant for all or only a subset of galaxies. An important mechanism connecting AGN to their host galaxies is AGN feedback, potentially heating up or even expelling gas from galaxies. AGN feedback may hence be responsible for the eventual quenching of star formation and halting of galaxy growth. A rich multi-wavelength dataset ranging from the X-ray regime (Chandra), to far-IR (Herschel), and radio (WSRT) is available for the North Ecliptic Pole field, most notably surveyed by the AKARI infrared space telescope, covering a total area on the sky of 5.4 sq. degrees. We investigate the star formation properties and possible signatures of radio feedback mechanisms in the host galaxies of 237 radio sources below redshift z = 2 and at a radio 1.4 GHz flux density limit of 0.1 mJy. Using broadband SED modelling, the nuclear and host galaxy components of these sources are studied simultaneously as a function of their radio luminosity. Here we present results concerning the AGN content of the radio sources in this field, while also offering evidence showcasing a link between AGN activity and host galaxy star formation. In particular, we show results supporting a maintenance type of feedback from powerful radio-jets.

• 한국식품영양과학회지
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• 제33권10호
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• pp.1668-1675
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• 2004

근원섬유단백질과 알칼리 용액으로 처리하여 회수한 단백질의 가열 중 ANS 소수성의 변화, IR스펙트럼의 변화, SH기의 변화, 전기영동상의 변화 및 엔탈피의 변화로 비교하여 회수 단백질의 가열 변성기구를 조사하였다. 갈고등어와 냉동 꼬마민어의 근원섬유단백질은 가열 온도의 상승과 더불어 소수성 잔기가 외부로 노출되고 소수성 상호작용은 6$0^{\circ}C$ 부근에서 최대로 일어나지만, 근형질 단백질을 포함하는 회수단백질은 근원섬유 단백질과 ANS 소수성에서 차이를 보였다. pH가 증가함에 따라 1636 $cm^{-1}$ /에 해당하는 peak가 증가하였다. 반응성 SH기와 총 SH기 수의 차이는 pH 7.0과 pH 10에서 비교적 큰 것으로 나타났다. SDS-PAGE 상에서 pH가 상승함에 따라 myosin heavy chain의 중합체가 확인되었다. 알칼리 공정으로 제조한 회수 단백질을 시차주사열량계로 분석한 결과, 회수 단백질은 33.1,44.3 및 65.5$^{\circ}C$에서 전이 온도가 나타나며, myosin의 변성 에 해당하는 온도인 51.7$^{\circ}C$의 peak는 보이지 않았다. 회수 단백질의 가열 젤은 극단적 인 pH 처리에 의한 $\alpha$-helix 구조의 $\beta$-sheet 구조 전환, 가열에 의한 S-S 결합의 형성과, myosin heavy chain 중합체 형성에 의한 것으로 보인다.

• 자원환경지질
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• 제30권4호
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• pp.279-289
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• 1997

Dark to pale green-colored, Cr-bearing sericites from hydrothermal alteration zone of the Narim gold deposit were investigated mineralogically and geochemically. The alteration zone is composed mineralogically of quartz, carbonate minerals and green sericite with minor amounts of chlorite, barite and sulfide minerals (pyrite, sphalerite, galena). The zone is enriched in As (967 to 1520 ppm), Cu (31 to 289 ppm), Ni (1027 to 1205 ppm), Pb (0.20 to 1.24 wt.%) and Zn (1.03 to 1.07 wt. %) compared with fresh rocks such as granitic gneiss, porphyritic biotite granite and basic dyke. The Cr, probably the chromophore element, is highly enriched in the alteration zone (1140 to 1500 ppm), host granitic gneiss (1200 ppm) and porphyritic biotite granite (1200 ppm). Occurrence and grain size of sericite are diverse, but most of the Cr-bearing sericites (150 to $200{\mu}m$ long and 20 to $30{\mu}m$ wide) occur along the boundaries between ore veins and host rocks (especially basic dyke and granitic gneiss). X-ray diffraction data of the sericite show its monoclinic form with unit-cell parameters of $a=5.202{\AA}$, $b=8.994{\AA}$, $c=20.103{\AA}$, ${\beta}=95.746^{\circ}$ and $V=935.83{\AA}^3$, which are similar with the normal 2M1-type muscovite. Representative chemical formula of the sericite is ($K_{1.54}Ca_{0.03}Na_{0.01}$)($Al_{3.42}Mg_{0.38}Cr_{0.14}Fe_{0.06}V_{0.02}$)($Si_{6.69}Al_{1.31}$)$O_{20}(OH)_4$. The Cr content increases with decrease of the octahedral Al content, and ranges from 0.36 to 2.58 wt.%. DTA and TG curves of the sericite show endothermic peaks at $342^{\circ}$ to $510^{\circ}$, $716^{\circ}$ to $853^{\circ}$ and $1021^{\circ}C$, which are due to the expulsion of hydroxyl group. The total weight loss by heating is measured to be about 8.8 wt. %, especially at $730^{\circ}C$. Infrared absorption experiments of the sericite show broad absorption band due to the O-H bond stretching vibration near the $3625cm^{-1}$, coupled with the 825 and $750cm^{-1}$ doublet. The vibration bands related with the H-O-Al and Si-O-Al bonds occur at $1030cm^{-1}$ and 500 to $700cm^{-1}$, respectively. Based on paragonite content of the sericite, the formation temperature of the Narim gold deposit is calculated to be $220{\pm}10^{\circ}C$.

• 마이크로전자및패키징학회지
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• 제24권2호
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• pp.61-67
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• 2017

소자의 트랜지스터 밀도가 급속히 높아짐에 따라 소자 내부에서 발생하는 열 유속(heat flux) 또한 빠르게 증가하고 있다. 소자의 고열 문제는 소자의 성능과 신뢰성 감소에 크게 영향을 미친다. 기존의 냉각방법들은 이러한 고열문제를 해결하기 위해선 한계점에 다다랐고, 그 대안으로 liquid heat pipe, thermoelectric cooler, thermal Si via, 등 여러 냉각방법이 연구되고 있다. 본 실험에서는 직선형 마이크로채널과 TSV(through Si via)를 이용한 액체 냉각시스템을 연구하였다. 두 종류의 냉매(DI water와 ethylene glycol(70 wt%))와 3 종류의 금속 범프(Ag, Cu, Cr/Au/Cu)의 영향을 분석하였으며, 대류, 복사 및 액체 냉각으로 인한 총 열 유속을 계산하여 비교하였다. 냉각 전후의 냉각시스템의 표면온도는 적외선현미경을 통해 측정하였고, 마이크로채널 내 액체 흐름은 형광현미경을 이용하여 측정하였다. 총 열 유속은 ethylene glycol(70 wt%)의 경우 가열 온도 $200^{\circ}C$에서 $2.42W/cm^2$로 나타났으며 대부분 액체 냉각 효과에 의한 결과로 확인되었다.

• 한국결정성장학회지
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• 제20권5호
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• pp.237-242
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• 2010

Mg-BCP(Mg Substituted BCP)를 제조하기 위하여 $Ca(NO_3)_2{\cdot}4H_2O$(Katayama chemical, Japan)과 $(NH_4)_2{\cdot}HPO_4$ (Junsei chemical, Japan), $Mg(NO_3)_2{\cdot}6H_2O$(Junsei chemical, Japan)를 출발물질로 공침법(co-precipitation process)을 이용하여 합성하였다. 제조된 분말의 마그네슘의 첨가에 따른 분말의 분광학적 특성은 FT-IR(MAGNA-IR 560, Nicolet)을 통하여 분석하였으며, SEM(S-4200, Hitachi)을 통하여 미세구조를 분석하였다. XRD 회절피크의 면적적분강도를 Integral Analysis (Rigaku, Japan)를 이용하여 HAp와 ${\beta}$-TCP의 비율을 확인하였다. 1.0 wt% 마그네슘이 첨가된 BCP 샘플의 경우 Hank's solution에서의 2주 침적 후 표면에 침상의 HAp로 추정되는 결정이 성장하였다. 이러한 미세구조의 변화는 생활성을 가지는 마그네슘의 첨가가 BCP 조직 내에서 표면의 활성을 증가시켜 결정의 성장을 촉진시킨 것으로 판단된다.