• Journal of the Korean Magnetics Society
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• v.7 no.1
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• pp.13-18
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• 1997

The effects of the various raw material composition and sintered temperature on the physical properties of Ni-Zn ferrite have been investigated. They turned out to be spinel structure by X-ray diffraction and the size of grain from microscope was from 6 ${\mu}{\textrm}{m}$ to 16 ${\mu}{\textrm}{m}$. As the sintering temperature was increased from 1030 $^{\circ}C$ to 1070 $^{\circ}C$, the initial permeability and magnetic induction has increased and the both of Q factor and coercive force has decreased. The coercive force and curie temperature were almost the same at each specimen. Their values were about 0.20 Oe and 220 $^{\circ}C$. The frequency of specimen will used in the range from 400 kHz to 20 MHz. The basic composition of $Ni_{0.14}Zn_{0.64}Cu_{0.22}Fe_2O_4$ (specimen B) sintered at 1050 $^{\circ}C$ shows the best results at magnetic induction($B_r & B_m$).

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.52.1-52.1
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• 2011

최근에 에너지 자원의 고갈이 다가오는 상황에서 태양전지 분야가 주목받고 있으며 이에 대한 시장이 급격하게 확대되고 있다. 그러나 현재의 태양전지는 주를 이루고있는 실리콘태양전지의 경우 원재료 수급이 불안정하여 가격 변동이 심하다. 따라서 이를 대체할 2세대 태양전지인 박막형 태양전지의 연구가 활발히 이루어지고 있다. 박막형 태양전지 중에서도 주목받고 있는 것은 Cu(In,Ga)$Se_2$(CIGS)박막 태양전지이다. CIGS는 Ga의 농도에 따라 1.02~1.68eV의 다양한 에너지 밴드갭을 갖는 직접천이형 반도체 물질이다. 또한 $1{\times}10^5cm^{-1}$의 높은 광흡수계수를 가지고 있으며, $450{\sim}590^{\circ}C$의 고온공정에서도 매우 안정하여 열화현상이 거의 보이지 않아 박막형 광흡수층 재료로서 적합하다. 흡수층을 제조하는 방법은 여러 가지가 있지만, 본 연구에서는 균일성이 뛰어나고 원료사용효율이 높은 sputtering 방법을 사용하였다. 그리고 결정화하기위해서 유독기체를 사용하는 셀.렌.화. (selenization) 방법 대신 전자빔을 조사하는 방법을 채택하였다. sputtering을 통한 CIGS precursor을 제조하기위해 2~3개의 화합물target을 사용하는데, 대표적인 방법으로 동시에 sputtering하는 co-sputtering 방법과 각각의 단일 층을 쌓아 제조하는 stack형으로 분류된다. 본 연구는 CIGS precursor를 제조하기 앞서 CuGa 단일 층만을 제조하여 공정조건에 따른 박막을 제조하였다. 제조된 CuGa 단일층은 전자빔 처리에 따른 영향을 알아보기 위해 전자빔의 세기와 공정시간을 달리하여 특성을 알아보았다. 실험에서는 Cu:75wt%,Ga:25wt% 조성의 target을 사용하여 공정 압력을 각각 10~1mTorr로 변화시키며 실험을 실시하였으며 공정 power는 50W, 70W, 100W로 변화 시키며 실험을 실시하였다. 이때 실험의 초기진공은 turbo-molecular pump를 이용하여 $1{\times}10^{-6}torr$ 이하로 하였으며, Target과 기판사이의 거리는 모두 같은 조건으로 고정하여 실험을 실시하였다. 박막의 균일성을 증가시키기 위하여 5 rpm의 속도로 기판을 회전하였으며 기판 온도는 가열하지 않고 상온에서 전구체를 증착하였다. 그 후 전자빔의 세기를 고정 시킨 후 전자빔 조사 시간을 조절하여 전자빔 조사 전후의 특성을 각각 분석하였다. 전기적특성은 Hall effect, 4-point probe, 구조적 특성은 SEM,EDS, XRD, XRF 를 이용하여 분석하였다.

• Korean Journal of Medicinal Crop Science
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• v.11 no.2
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• pp.115-121
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• 2003

Essential oils from Fennel fruit(Foeniculum vulgare Mill), Olibanum resin(Boswellia carteii Birew) and Needl Juniperus stem(Juniperus rigida Sieb.) were extracted by a supercritical fluid extraction system(SFE) and biological activity of each essential oils were observed. SFE technique was applied for the isolation and purification of nonpolar biologically active essential oils from each samples. The quantitative analysis of essential oils was carried out by gas chromatography-mass spectrometer(GC/MS). About 60% of the growth of AGS and A549 cells were inhibited by adding 1.0g/l of the crude essential oils and below 40% was observed by the control. Cytotoxicity on human normal lung cell(HEL299) was scored as $15{\sim}18%$ for the crude essential oils and 12% for control, respectively. It meant that the essential oils were more effective than the control in anti-mutagenecity tested by CHO V79 cells. The effect of the essential oils on the growth of nerve cells, PC12 was observed as follows: The viable cell density was about two times higher than control.

• Journal of Biosystems Engineering
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• v.42 no.4
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• pp.350-357
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• 2017

Purpose: In-situ monitoring of water quality is fundamental to most environmental applications. The high cost and long delays of conventional laboratory methods used to determine water quality, including on-site sampling and chemical analysis, have limited their use in efficiently managing water sources while preventing environmental pollution. The objective of this study was to develop an on-site water monitoring system consisting mainly of an Arduino board and a sensor array of multiple ion selective electrodes (ISEs) to measure the concentration of $NO_3$ ions. Methods: The developed system includes a combination of three ISEs, double-junction reference electrode, solution container, sampling system consisting of three pumps and solenoid valves, signal processing circuit, and an Arduino board for data acquisition and system control. Prior to each sample measurement, a two-point normalization method was applied for a sensitivity adjustment followed by an offset adjustment to minimize the potential drift that could occur during continuous measurement and standardize the response of multiple electrodes. To investigate its utility in on-site nitrate monitoring, the prototype was tested in a facility where drinking water was collected from a water supply source. Results: Differences in the electric potentials of the $NO_3$ ISEs between 10 and $100mg{\cdot}L^{-1}$ $NO_3$ concentration levels were nearly constant with negative sensitivities of 58 to 62 mV during the period of sample measurement, which is representative of a stable electrode response. The $NO_3$ concentrations determined by the ISEs were almost comparable to those obtained with standard instruments within 15% relative errors. Conclusions: The use of the developed on-site nitrate monitoring system based on automatic sampling and two-point normalization was feasible for detecting abrupt changes in nitrate concentration at various water supply sites, showing a maximum difference of $4.2mg{\cdot}L^{-1}$ from an actual concentration of $14mg{\cdot}L^{-1}$.

• Korean Journal of Animal Reproduction
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• v.21 no.3
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• pp.303-310
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• 1997

소 난포란의 체외성숙시 성숙배지에 FSH 및 LH의 첨가가 체외성숙난자의 calcium 반응과 체외수정란의 발달에 미치는 영향을 조사하였다. 난포란의 체외성숙은 TCM199을 기초로 한 4가지의 배양조건 하에서 : 1) 0.5$\mu\textrm{g}$/ml FSH＋5$\mu\textrm{g}$/ml LH, 2) 0.5$\mu\textrm{g}$/ml FSH, 3) 5$\mu\textrm{g}$/ml LH 및 4) 무 호르몬 첨가구로서 5% CO2에 24시간 동안 체외성숙을 유도하였다. 체외성숙 24기간째에 난포란의 과립막세포는 1ml PB1＋에서 4분 동안 vortexing을 하여 완전히 제거하였다. 세포 내 calcium 반응을 측정하기 위하여 2mM Fura-2 AM ester 및 0.02% Pluronic F-127가 첨가된 PB1-용액에 39$^{\circ}C$ in cubator에서 40분 동안 배양하였다. 30${\mu}\ell$ M2 medium drop을 30mm plastic dish에 만들어 20$\times$ 형광대물렌즈가 장착된 Nikon Diaphot 현미경의 장착된 Nikon Diaphot 현미경의 warm stage에 설치하였다. 세포 내 calcium 방출을 자극하기 위하여 난자에 25mM inositol 1, 4, 5-trasphophate(IP3)로 1.21kV/cm의 전기자극 또는 20mM ryanodine으로 미세주입을 실시하였다. 이러한 처리를 하지 않은 난자는 체외수정 후 CR1aa와 BRL monolayers의 공배양조건 하에서 체외발달을 유도하였다. 분할율(Day 2)과 배반포기발달율(Day 9)을 조사하였다. FSH와 LH의 처리구에서 IP3 또는 ryanodine으로 자극된 난자(1.79$\pm$0.05, 1.66$\pm$0.06)는 FSH, LH 및 무 호르몬처리구에 비하여 유의적으로 높은 calcium 반응을 보였다(1.00$\pm$0.03, 1.28$\pm$0.04, and 0.53$\pm$0.02 in IP3 elctroporation; 0.68$\pm$0.05, 1.03$\pm$0.05, and 0.47$\pm$0.04 in ryanodine microinjection). FSH와 LH, FSH, LH처리구에서 분할율(87.9, 71.5 및 75.6%)은 무 호르몬처리구(60.7%)(P<0.05)에 비하여 유의적으로 높았으며, FSH와 LH처리구(29.3%)에서의 배반포기 발달율은 FSH, LH 처리구뿐만 아니라 무 호르몬처리구보다 유의적으로 높았다(16.5, 19.0 and 9.8%)(P<0.05). Bovine FSH 및 Ovine FSH의 처리구에서의 calcium 반응은 유의적인 차이가 없었다(1.72$\pm$0.05, 1.61$\pm$0.06). 또한 분할율(82.2 and 84.0%) 및 배반포기(27.8 and 27.1%) 발달율도 bovine 및 ovine FSH처리구간에는 유의적인 차이가 없었다. 이상의 결과에서 전기자극에 의한 세포 내 calcium 반응은 체외성숙배지에 첨가하는 호르몬의 처리에 따라서 유의적인 변화를 보였다. 비록 분할율은 처리구간에 유의적인 차이가 없었지만 배반포기 발달율은 FSH와 LH 공동처리구에서 FSH, LH 단독처리구 및 무 호르몬처리구에 비하여 유의적으로 높은 발달율을 보였다. 체외성숙기간에 FSH와 LH의 공동첨가는 체외성숙 및 체외발달의 생리적인 교정을 위하여 요구되는 것으로 사려된다.

• Economic and Environmental Geology
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• v.20 no.2
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• pp.85-95
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• 1987

The host rocks of titaniferous magnetite deposits in Gonamsan are alkaline gabbros, which are typical of undersaturated alkaline rocks in terms of the lack of normative quartz. According to field occurrences and petrographic features, these alkaline gabbros are divided into 3 rock types: coarse-grained and pegmatitic rock, medium-grained rock with equigranular texture, and layered cumulate rock. All these rocks mainly contain clinopyroxene(salite), plagioclase(An 43-66), pargasite, and ilmenite. The accessory minerals are apatite, sphene, quartz, and sometimes titaniferous magnetite. Pargasite, sphene, and quartz are considered to be secondary minerals formed by the reaction among clinopyroxene, plagioclase and Fe-Ti oxide at deuteric stage. Fe-Ti oxides generally occur as ilmenite in the alkaline rocks, and titaniferous magnetite in the ore deposits. Layered cumulate rocks are characterized by a recurrence of discontinuous thin mesolayer of clinopyroxene-pargasite within leucolayer mainly composed of plagioclase. Clinopyroxene is cumulus mineral whereas plagioclase, ilmenite and apatite occur as intercumulus minerals. According to the variation diagrams of oxide and trace element contents against the differentiation index, incompatible elements, such as Na, Ba and Sr, show positive correlations whereas compatible elements, such as Mg and Cr, show negative correlations. However some compatible elements, such as Co, Ni and V show irregular variations, reflecting relative cumulate status of cumulus and intercumulus minerals. On the de la Roche multicationic diagram, these alkaline gabbros are distributed along the differentiation curve of undersaturated alkaline series from alkaline basaltic composition through basanitic composition to tephritic composition. Layered cumulate rocks, which are distributed between basanitic composition and tephritic composition, reflect their cumulate character, slightly scattering away from the curve. The medium-grained rock shows higher contents in Ba, Sr and light rare earch elements than the coarse-grained and pegmatitic rock. The former shows two times higher contents of total rare earth elements than the latter, $while(La/Lu)_{cn}$ ratios maintain fairly constant values of 5.08~5.06 in these two rocks. This means that coarse-grained and pegmatitic rock, as compared with the medium-grained rock, was formed by the earlier differentiated magma but rare-earth element distribution pattern remained almost parallel during differentiation. From the data the above mentioned, these alkaline gabbros are considered to be comagmatic and to be formed by intrusions of differentiated magmas in its reservoir.

• Journal of Bio-Environment Control
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• v.15 no.1
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• pp.47-52
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• 2006

This studies were carried out in summer season to increase high temperature tolerance using hydrogen peroxide treatments on cucumber in greenhouse. The water stress of cucumber in greenhouse by the hydrogen peroxide treatments showed as control>250 mM>500 mM treatments in order. The photosynthesis rate of cucumber at $30^{\circ}C$ did not show difference with each hydrogen peroxide treatment in temperature controlled greenhouse. However, the photosynthesis rate of cucumber in the control and hydrogen peroxide treatments at $40^{\circ}C$ was significantly different. The photosynthesis rate of cucumber in combined treatment with 1,000 $mg{\cdot}L^{-1}\;CO_2$ supply and hydrogen peroxide was also higher than control, however, there was no different of photosynthesis in 250 mM and 500 mM treatment. The value of $F_v/F_m$ and $F_m/F_o$ of chlorophyll fluorescent in 500 mM hydrogen peroxide treatment at $40^{\circ}C$ was highest. Also the activity of POD, the antioxidant enzyme, was higher with high hydrogen peroxide concentration than the other treatments. The high temperature limits for growth were $43^{\circ}C$ in the control, $44^{\circ}C$ in the 250 mM and $46^{\circ}C$ in the 500 mM according to analyze chlorophyll fluorescent $F_o$. The high temperature tolerance in cucumber increased approximately $3^{\circ}C$ by the hydrogen peroxide treatments under this experiment conditions.

• Journal of Embryo Transfer
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• v.13 no.1
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• pp.11-19
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• 1998

This study was to determine the effect of ionomycin and 6-dimethylaminopurine (6-DMAP) and/or elcetrical stimulation on the oocyte activation and production of rabbit nuclear transplant embryos. The oocytes were collected from the oviduct of superovulated rabbits at 14 h post hCG injection and cultured in TCM-199 containing 10% FBS until 19 h post hCG injection. To determine the optimum concentration and exposure time of 6-DMAP, some oocytes were activated with 5 $\mu$M ionomycin for 5 min and then in 2.0 mM 6-DMAP for 0.5 to 3.0 h, or in 1.0 to 3.0 mM 6-DMAP for 2.0 h. Other control oocytes were stimulated electrically(3X, 1.25 kV/cm, 60 $\mu$sec) in 0.3 M mannitol solution supplemented with 100 $\mu$M CaCl$_2$ and MgCl$_2$. The nuclear donor embryos of 8-cell stage were synchronized to G$_1$ phase of 16-cell stage, and the recipient cytoplasms were obtained from removal of the first polar body and a portion of membrane bound cytoplasm of the oocytes collected at 15 h post hCG injection. A separated blastomere was injected into the perivitelline space of the enucleated oocytes. The oocytes injected with nucleus were cultured until 19 h post hCG and then electrofused and activated by electrical stimulation with or without ionomycin and 6-DMAP. These nuclear transplant embryos were cultured in TCM-199 containing 10% FBS in 39˚C, 5% CO2 incubator for 120 h. For the oncytes activated parthenogenetically with electrical stimulation with or with-out ionomycin and the various concentration of exposure time of 6-DMAP, the highest cleavage(92.3%) and development to blastocyst stage(41.0%) were resulted from the oocytes activated by ionomycin and 2.0 mM 6-DMAP for 2.0 h, which were found to be significantly(P<0.05) higher than the cleavage(45.2%) and developement to blastocyst stage(14.3%) from the oocytes activated with electrical stimulation. The significantly(P<0.05) more oocytes(71.4%) developed to 4 cell stage at 24 h post activation by ionomycin and 6-DMAP than those by electrical stimulation(18.9%). For the nuclear transplant embryos, the cleavage rate was similarly high in oocyte activation by electrical stimulation with(79.4%) or without ionomycin and 6-DMAP(70.5%). However, the embryo development to blastocyst stage was significantly(P<0.05) higher in oocyte activation by electrical stimulation with ionomycin and 6-DMAP(44.4%) than by electrical stimulation only(25.0%). The significantly(P<0.05) more nuclear transplant embryos(45.6%) developed to 4 cell stage at 18 h post activation by electrical stimulation with ionomycin and 6-DMAP than those by electrical stimulation only(10.6%). These results indicated that the supplemental oocyte activation by ionomycin and 6-DMAP with electrical stimulation enhanced and accelerated the preimplanted in vitro development of the rabbit nuclear transplant embryos.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.5
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• pp.611-621
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• 2005

State of problem: Zirconia all-ceramic restoration fabricated with CAM system is on an increasing trend in dentistry. However, evaluation of the marginal and internal fits of zirconia bridge seldomly have been reported. Purpose: This study was to evaluate the at of margin and internal surface in posterior 3-unit zirconia bridge framework fabricated with CAM system(DeguDent, Germany). Material and Method: Preparations of secondary premolar and secondary molar on artificial resin model were performed for fabrication of 3-unit posterior bridge framework. Fits of 5 zirconia bridge framework were compared with 5 precious ceramo-metal alloy framework(V-GnathosPlus, Metalor, Switzerland), and prepared margins were designed to chamfer and shoulder finishing line. Each framework was cemented to epoxy resin model with reinforced glass ionomer(FujiCEM, GC Co., Japan), embedded in acrylic resin and sectioned in two planes, mesio-distal and buccolingual. Samples were divided into six pieces by sectioning and had two pieces of each surface(i.e mesial, distal, buccal and lingual surface) per abutment, so there were eight measuring points in each abutment. External gap was measured at the margin and internal gaps were measured at the margin, axial and occlusal surface. Gaps were observed under the measuring microscope(Compact measuring microscope STM5; Olympus, Japan) at a magnification of $\times100$. T-test were used to determine the statistic significance of the different gaps between zirconia and metal framework. Results and Conclusion: 1. External and internal marginal gaps of zirconia and metal framework were in clinically acceptable range. External marginal gaps were not different significantly between zirconia$(81.9{\mu}m)$ and metal $(81.3{\mu}m)$ framework and internal marginal gaps of zirconia $(44.6{\mu}m)$ were smaller than those of metal framework $(58.6{\mu}m)$. 2. Internal axial gaps of zirconia framework$(96.7{\mu}m)$ were larger than those of metal frame-work$(78.1{\mu}m)$ significantly and adversely, internal occlusal gaps of zirconia frame-work$(89.4{\mu}m)$ were smaller than those of metal framework $(104.9{\mu}m)$ significantly. 3. There were no significant differences in external and internal marginal gaps between chamfer and shoulder finish line when zirconia frameworks were fabricated.

• Journal of the Korean Ceramic Society
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• v.51 no.4
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• pp.271-277
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• 2014

To overcome the limitations of the solid oxide fuel cells (SOFCs) due to the high temperature operation, there has been increasing interest in proton conducting fuel cells (PCFCs) for reduction of the operating temperature to the intermediate temperature range. In present work, the perovskite $BaCe_{0.85-x}Zr_xY_{0.15}O_{3-\delta}$ (BCZY, x = 0.1, 0.3, 0.5, and 0.7) were synthesized via solid state reaction (SSR) and adopted as an electrolyte materials for PCFCs. Powder characteristics were examined using X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Brunauer, Emmett and Teller (BET) surface area analysis. Single phase BCZY were obtained in all compositions, and chemical stability was improved with increasing Zr content. Anode-supported cell with $Ni-BaCe_{0.55}Z_{0.3}Y_{0.15}O_{3-\delta}$ (BCZY3) anode, BCZY3 electrolyte and BCZY3-$Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-\delta}$ (BSCF) composite cathode was fabricated and electrochemically characterized. Open-circuit voltage (OCV) was 1.05 V, and peak power density of 370 ($mW/cm^2$) was achieved at $650^{\circ}C$.