• 한국재료학회지
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• 제22권9호
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• pp.489-493
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• 2012

Green phosphors $K_2BaW_2O_8:Tb^{3+}$(1.0 mol%) were synthesized by solid state reaction method. Differential thermal analysis was applied to trace the reaction processes. Three endothermic values of 95, 706, and $1055^{\circ}C$ correspond to the loss of absorbed water, the release of carbon dioxide, and the beginning of the melting point, respectively. The phase purity of the powders was examined using powder X-ray diffraction(XRD). Two strong excitation bands in the wavelength region of 200-310 nm were found to be due to the ${WO_4}^{2-}$ exciton transition and the 4f-5d transition of $Tb^{3+}$ in $K_2BaW_2O_8$. The excitation spectrum presents several lines in the range of 310-380 nm; these are assigned to the 4f-4f transitions of the $Tb^{3+}$ ion. The strong emission line at around 550 nm, due to the $^5D_4{\rightarrow}^7F_5$ transition, is observed together with weak lines of the $^5D_4{\rightarrow}^7F_J$(J = 3, 4, and 6) transitions. A broad emission band peaking at 530 nm is observed at 10 K, while it disappears at room temperature. The decay times of $Tb^{3+}$ $^5D_4{\rightarrow}^7F_5$ emission are estimated to be 4.8 and 1.4 ms, respectively, at 10 and 295 K; those of the ${WO_4}^{2-}$ exciton emissions are 22 and 0.92 ${\mu}s$ at 10 and 200 K, respectively.

• Applied Biological Chemistry
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• 제36권4호
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• pp.310-314
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• 1993

HPLC를 이용하여 fructose oligomer인 fructo올리고당(GF2-GF7) 및 inulo올리고당(F2-F4)의 분리, 정량을 실시하였다. TSK-gel amide 80 column과 acetonitrile-water(65:35; v/v) 용매를 사용하여 각 표준당들을 효과적으로 분리할 수 있었으며 이들의 retention time은 분석시마다 거의 변하지않아 재현성이 있었다. 각 당의 농도에 따른 peak면적을 이용하여 표준곡선을 작성한 결과 넓은 당량의 범위에 걸쳐 결정계수가 0.9884이상의 값을 보여 본 HPLC방법에 의한 정량법이 타당한 것으로 나타났다. 또한 기울기는 비슷하나 y축 절편 값이 당마다 크게 상이하여 몇가지 표준당들을 기준으로 하여 모든 당을 일률적으로 정량하는 것은 적합하지 않으며 각 당에 대한 표준곡선을 하나씩 작성하여 정량하여야함을 알 수 있었다.

• 생명과학회지
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• 제8권4호
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• pp.437-442
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• 1998

대두에서 종자크기와 앞 크기와의 관계를 알아보기 위하여 두 형질에서 큰 차이를 보이는 12 strain을 선택하여 half diallel mating system으로부터 만들어진 66개의 $F_2$ 분리집단을 대상으로 양 형질에 대한 관계를 조사한 결과는 다음과 같다. 종자크기 (g/100 seed)는 6.7에서 43.8의 변이를 보였고, 잎의 넓이와 길이(cm)에서는 각각 5.7에서 8.6과 9.4에서 12.9의 변이를 보였다. $F_2$ 집단에서의 잎의 넓이와 길이는 고도의 유의한 정의 상관관계를 보였고, 종자 크기와 잎 크기에서도 동일한 경향을 보여, 잡종집단 및 germplasm 내에서 일반적으로 큰 잎 형질과 대립종자 형질은 고도의 정의 상관관계가 있는 것으로 사료된다. 따라서, 대두 잡종집단에서나 germplasm내에서 어린 식물체를 대상으로 하는 생육초기에서 대립종자를 가진 genotype를 선발하기 위해서 큰 잎을 가진 genotype의 선발은 효과적인 수단이 될 것으로 보인다.

• Restorative Dentistry and Endodontics
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• 제22권1호
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• pp.396-412
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• 1997

The purpose of this study is to observe the corrosion characteristics of five dental amalgams(CAULK FINE CUT, OPTALLOY II, DISPERSALLOY, TYTIN, and VALIANT) in the solutions with fluoride compound through the anodic polarization curve obtained by using a potentiostat. After each amalgam alloy and Hg being triturated, the triturated mass was inserted into the cylindrical metal mold, and condensed by hydraulic pressure(160 kg/$cm^2$). Each specimen was removed from the metal mold. Specimens were polished with the silicone carbide grinding paper 24 hours after condensation and stored at room temperature for 1 week. The anodic polarization curves were employed to compare the corrosion behaviours of the amalgams in 0.9 % saline solution and in the saline solutions with 2.2 ppm, 0.05 %, 2 % NaF, and 8 % $SnF_2$ at $37^{\circ}C$ with 3-electrode potentiostat. After the immersion of specimen in electrolyte for 30 minutes, the potential scan was begun. The potential scan range was -1500m V to + 800m V(vs. S.C.E.) in the working electrode and the scan rate was 50 mV/sec. The results were as follows, 1. The corrosion potential, the potential of anodic current peak, and transpassive potential in the saline solutions with NaF shifted to lower direction than those in normal saline solution, and the current density in the saline solutions with NaF was higher than that in normal saline solution. The differences were increased as the concentrations of NaF became higher. 2. The corrosion potential and transpassive potential in the saline solution with $SnF_2$ shifted to higher direction than those in normal saline solution, and the current density in the saline solution with $SnF_2$ was higher than that in normal saline solution after the corrosion potential. The anodic polarization curves in the saline solution with $SnF_2$ had no outstanding anodic current peak. 3. The corrosion potentials for high-copper amalgams were much higher than those for CAULK FINE CUT and OPTALLOY II in normal saline solution, but, as the concentrations of fluoride compound became higher, the differences in corrosion potentials between them were decreased. The corrosion potentials had the similarity in the saline solution with 2% NaF or 8% $SnF_2$. 4. The current density for TYTIN was the lowest among the others in normal saline solution and in the saline solution with 2.2 ppm or 0.05 % NaF. 5. There was no significant difference in current density between Pd-enriched VALIANT and other high-copper amalgams.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1993년도 추계 학술발표 강연 및 논문 개요집
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• pp.69-71
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• 1993

Fluoride compound potentiometric cell oxygen sensors were fabricated for the measurement of oxygen pressure in the low temperature range (300。K-500。K). The disk type sensors consist of a reference Air(0$_2$):Ag, a solid electrolyte SrF$_2$, and a sensing metel Ag electrode. And the buried reference electrode type sensor have a NiO/Ni reference electrode. The open circuit emf of the cell showed high sensivity to oxygen gas (60mv) at the measuring temperature 20$0^{\circ}C$. Also, The buried reference electrode type sensor showed 30mv from 1% to 10% oxygen pressure range.

• 한국임상수의학회지
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• 제15권2호
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• pp.267-273
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• 1998

The study was carried out to investigate the changes of total WBC, neutrophil, lymphocyte, monocite, eosinophil in the horses'blood of 3 groups which randomly assigned 3 heads to each group. In group A(daily therapy), each horse was iniected, intramuscularly, 100 mg of prednisolone acetate/day for 3 days, consecutively. In group B(alternate-day therapy), each horse was injected, 100 mg of prednisolone acetate/day 4 times on alternate days, intramuscularly. In control group, each horse was injected, intramuscularly, the equivalent volumes/day of saline solution fur 3 days, consecutively. The results were summarized as fellows: 1. Total WBC counts in group A rapidly increased until day 4th, which the counts reached the $maximum(13.10{\pm}0.13{\times}10^{3}/{\mu}l$)(p<0.05), and decreased into control group range until day loth. In group B rapidly increased until day 1st, and gradually increased until day 71% which the counts reached the maximum ($12f3{\pm} 0.20$)0<0.05), and decreased into control group range until day 16th. 2. Neutrophil counts in group A rapidly increased until day 4HL which the coun% reached the maxi um($10.85{\pm} 0.08$)0<0.05), and decreased into control group range until day loth. In group B rapidly increased until day 1st and slowly increased until day 7th, which the counts reached the maximum$(9.76{\pm}0.22)0<0.05)$, and decreased into control group range until day 16th. 3. Lymphocyte counts in group A and B rapidly decreased until day 4th, which the counts reached the minimum(2.14{\pm}0.12 and 2.09{\pm}0.20$, respectively) (p<0.05), and increased into control group range until day 10th. Group A and B, however, had no significant effects each other on Iymphocyte counts during the study. 4. Monocite and eosinophil counts in group A and B remained in the range of control group during the study. Eosinophil in group A and B slightly decreased on day 4th, significantly%<0.05), but we could not generally be reliable the result because of severe standard deviations. In conclusion, we fecund that group A had more rapidly increase and decrease than group B on hematologic counts of WBC, but group B had longer period than group A on the hematologic effects of WBC, and found not differences between daily therapy and alternate-day therapy.

• 대한원격탐사학회지
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• 제38권3호
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• pp.265-282
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• 2022

해수면 온도(Sea surface temperature, SST)는 지구시스템에서 해양의 순환과 생태계에 큰 영향을 주는 요소이다. 지구온난화로 한반도 근해 해수면 온도에 변화가 생기면서 이상 수온(고수온, 저수온) 현상이 발생하여 해양생태계와 수산업 피해를 지속적으로 발생시키고 있다. 따라서 본 연구는 한반도 근해 해수면 온도를 예측하여 이상 수온 현상 예측으로 피해를 예방하는 방법론을 제안한다. 연구 지역은 한반도 근해로 설정하여 동시간대 해수면 온도 데이터를 사용하기 위해 Europe Centre for Medium-Range Weather Forecasts (ECMWF)의 ERA5 자료를 사용하였다. 연구방법으로는 해수면 온도 데이터의 시계열 특징을 고려하여 딥러닝 모델 중 시계열 데이터 예측에 특화된 Long Short-Term Memory (LSTM) 알고리즘을 이용하였다. 예측 모델은 1~7일 이후 한반도 근해 해수면 온도를 예측하고 고수온(High water temperature, HWT) 혹은 저수온(Low water temperature, LWT) 현상을 예측한다. 해수면 온도 예측 정확도 평가를 위해 결정계수(Coefficient of determination, R²), 평균제곱근 편차(Root Mean Squared Error, RMSE), 평균 절대 백분율 오차(Mean Absolute Percentage Error, MAPE) 지표를 사용하였다. 예측 모델의 여름철(JAS) 1일 예측 결과는 R²=0.996, RMSE=0.119℃, MAPE=0.352% 이고, 겨울철(JFM) 1일 예측 결과는 R²=0.999, RMSE=0.063℃, MAPE=0.646% 이었다. 예측한 해수면 온도를 이용하여 이상 수온 예측 정확도 평가를 F1 Score로 수행하였다(여름철(2021/08/05) 고수온 예측 결과 F1 Score=0.98, 겨울철(2021/02/19) 저수온 예측 결과 F1 Score=1.0). 예측 기간이 증가하면서 예측 모델이 해수면 온도를 과소추정하는 경향을 보여주었고, 이로 인해 이상 수온 예측 정확도 또한 낮아졌다. 따라서, 향후 예측 모델의 과소추정 원인을 분석하고 예측 정확도 향상을 위한 연구가 필요할 것으로 판단된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.407-410
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• 2000

(M $n_{l-x}$M $g_{l-x}$)F $e_{2+x}$ $O_4$(x=0.0, 0.025, 0.1, 0.2) for NTC(negative temperature coefficient) thermistor was prepared by calcining at 80$0^{\circ}C$ and sintering at from 1100 to 130$0^{\circ}C$ with 5$0^{\circ}C$ intervals while x was varied from 0.0 to 0.025, 0.1 and 0.2. The best linear property was obtained in the based specimen sintered at 120$0^{\circ}C$ with x=0.1 composition. Thermistor parameter, $B_{25~85^{\circ}C}$, was in the range of 5000~ 7300 [K]. Temperature coefficient of resistance, $\alpha$$_{25^{\circ}C}$, was -5.2 %/$^{\circ}C$. The results showed the possibility that Mn-Ni-Co based thermistor could be substituted by the composition used in this study was confirmed.med.d.

• 한국재료학회지
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• 제9권4호
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• pp.414-418
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• 1999

Typical metal oxide thin films having optical and electrical properties are widely used as inorganic functional materials. Liquid phase deposition(LPD) method, a new low temperature process, has been developed for the several advantages of no vacuum system, low cost, high throughput, and low processing temperature(<$50^{\circ}C$). Silica powder was added to 40wt% hydrofluoro-silicic acid($H_2$SiF\ulcorner) to obtain an immersing solution of silica-saturated hydrofluorosilicic acid solution. Boric acid solution was continuously added in the range from 0 to 0.05M to prepare supersaturated hydrofluorosilicic acid solution. LPD $SiL_2$film was formed with the variation of added amount of $H_2$O. The SiO$_2$thin film could be prepared from hydrofluorosilicic acid by LPD method. The thickness of LPD $_SiO2$film was influenced by the boric acid concentration and added amount of $H_2$O. Silicon in thin film existed as SiF\ulcorner by Raman spectrum.

• Nuclear Engineering and Technology
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• 제51권3호
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• pp.818-824
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• 2019

In the present work, we determined the gamma-ray attenuation characteristics of eight different polymers(Polyamide (Nylon 6) (PA-6), polyacrylonitrile (PAN), polyvinylidenechloride (PVDC), polyaniline (PANI), polyethyleneterephthalate (PET), polyphenylenesulfide (PPS), polypyrrole (PPy) and polytetrafluoroethylene (PTFE)) using transmission geometry utilizing the high resolution HPGe detector and different radioactive sources in the energy range 81-1333 keV. The experimental linear attenuation coefficient values are compared with theoretical data (WinXCOM data). The linear attenuation coefficient of all polymers reduced quickly with the increase in energy, at the beginning, while decrease more slowly in the region from 267 keV to 835 keV. The effective atomic number of PVDC and PTFE are comparatively higher than the $Z_{eff}$ of the remaining polymers, while PA-6 possesses the lowest effective atomic number. The half value layer results showed that PTFE ($C_2F_4$, highest density) is more effective to attenuate the gamma photons. Also, the theoretical results of macroscopic effective removal cross section for fast neutrons ($\sum_{R}$) were computed to investigate the neutron attenuation characteristics. It is found that the $\sum_{R}$ values of the eight investigated polymers are close and ranged from $0.07058cm^{-1}$ for PVDC to $0.11510cm^{-1}$ for PA-6.