• 한국전기전자재료학회논문지
• /
• 제14권7호
• /
• pp.572-577
• /
• 2001

The electrical properties of Pr$_{6}$ O$_{11}$ -based ZnO varistors consisting of ZnO-Pr$_{6}$ O$_{11}$ -CoO-Cr$_2$O$_3$-Er$_2$O$_3$ ceramics were investigated with sintering temperature in the range of 1325~f1345$^{\circ}C$. As sintering temperature is raised., the nonlinear exponent was increased up to 1335$^{\circ}C$, reaching a maximum 70.53, whereas raising sintering temperature further caused it to decrease, reaching a minimum 50.18 and the leakage current was in the range of 1.92~4.12 $\mu$A. The best electrical properties was obtained from the varistors sintered at 1335$^{\circ}C$, exhibiting a maximum (70.53) in the nonlinear exponent and a minimum (1.92 $\mu$A) in the leakage current, and a minimum (0.035) in the dissipation factor. On the other hand, the donor concentration was in the range of (0.90~1.14)x10$^{18}$ cm$^{-3}$ , the density of interface states was in the range of (2.69~3.60)x10$^{12}$ cm$^{-2}$ , and the barrier height was in the range of 0.77~1.21 eV with sintering temperature. With raising sintering temperature, the variation of C-V characteristic parameters exhibited a mountain type, reaching maximum at 134$0^{\circ}C$. Conclusively, it was found that the V-I, C-V, and dielectric characteristics of Pr$_{6}$ O$_{11}$ -based ZnO varistors are affected greatly by sintering temperature.

• 약학회지
• /
• 제42권2호
• /
• pp.153-158
• /
• 1998

Calcium hydrogen phosphate was synthesized by reacting calcium chloride and sodium hydrogen phosphate solution in this study. It is well known that the particle size and yield o f calcium hydrogen phosphate produced is greatly affected by the synthetic conditions such as the reactant concentration, reaction temperature, reacting fine, mole ratio and drying temperature, etc. The purpose of this study is to investigate the optimum synthesis condition from the viewpoint of yield and sedimentation volume of the prepared calcium hydrogen phosphate powder according to a randomized complete block design proposed by G.E.P. Box and K.B. Wilson. It was found that the optimum synthetic conditions of calcium hydrogen phosphate were as follows: It was found that optirnum temperature range of reactant solutions was $28-38^{\circ}C$ and $32-42^{\circ}C$ respectively, on the viewpoint of yield and sedimentation volume. The optimum concentration range of reactant solutions was 5.5-10.0% and 6.9-7.4% respectively, on the viewpoint of yield and sedimentation volume. The optimum mole ratio of $CaCl_2$ to $Na_2HPO_4$ was in the range of 1.2-2.0 and the optimum reacting time range was 8.5-11.0 minutes. The optimum drying temperature range was $39-41^{\circ}C$ from the viewpoint of yield, but it was $39-43^{\circ}C$ on the basis of sedimentation volume. Crystallographic analysis to X-ray diffraction patterns of commercially available ecalcium hydrogen phosphate and calcium hydrogen phosphate samples prepared in this study suggested that all samples tested belonged to monoclinic crystal system characteristic of $CaHP0_4{\cdot}2H_20$ crystals.

• 수산해양기술연구
• /
• 제31권1호
• /
• pp.45-53
• /
• 1995

Working depth of the model net was determined by using of the same experimental tank and the same model net that used in the forwarded report in a series studies. The depth of the net which indicates the depth of the head rope from the water surface, was determined by the photographs taken in front of the net mouth with the combination of towing velocity, warp length and distance between paired boats. The results obtained can be summarized as follows: 1. Working depth of model nets A and B was varied in the range of 0.09~1.66$m$,and 0.04~1.34$m$(which can be converted into 2.7~40.2$m$and 1.2~49.8$m$in the full-scale net) respectively, and the depth of model net A was slightly deeper than the depth of the model net B. 2. Working depth ($D$,which is appendixed m for the model net, f for the full-scale net, A and B for the types of the model nets) can be expressed as the function of towing velocity$V_t$, as in the model net($V_t$=$m$/$sec$) $D_{mA}$=(-1.99+0.65$L_w$) $e^{-1.72V_t}$ $D_{mA]$=(-1.91+1.04 $L_w$) $e^{2.88V_t}$ in the full-scale net($V_t$=$k$'$t$ $D_{fA}$=(-29.32+0.65$L_w$)$e^{0.40 V_t}$ $D_{fB}$=(-57.60+1.04$L_w$)$e^{-0.67 V_t}$ 3. Working depth 9$D$ appendixes are as same as the former) can be expressed as the function of warp length$L_w$) in the model net, and can be converted into full-scale net as in the model net ($V_t$=$m$/$sec$) $D_{mA}$=-0.99 $e^{-1.42V_t}$+0.67$e^{-1359V_t}$$L_w$ $D_{mB}$=-.258$e^{-3.77V_t}$+1.16$e^{-3.15V_t$ $L^w$, in the full-scale net($V_t$=k't) $D_{fA}$=-29.28$e^{-0.32V_t}$+0.67$e^{-0.37V_t$$L_w$ $D_{fB}$=-69.10$e^{-0.81V_t}$+1.16$e^{-0.72V_t}$$L_w$. 4. Working depth was gradually shallowed according to the increase of the distance between paired boats.

• 대한기계학회논문집
• /
• 제19권4호
• /
• pp.1134-1147
• /
• 1995

POD (proper orthogonal decomposition) is applied to turbulent leading-edge separation bubble to extract coherent structures. A two-dimensional leading-edge separation bubble is simulated by discrete-vortex method, where a time-dependent source forcing is incorporated. Based on the wealth of numerical data, POD is applied in a range of the forcing amplitude ( $A_{o}$ = 0, 0.5, 1.0 and 1.5) and forcing frequency (0 .leq. $f_{F}$H/ $U_{\infty}$.leq. 0.3). It is demonstrated that the structures of POD have noticeable changes with local forcings. In an effort to investigate the mechanism of decreasing reattachment length, dynamic behaviors of the expansion coefficients and contributions of the eigenfunctions of POD are scrutinized. As the forcing amplitude increases, the large-scale vortex structures are formed near the forcing amplitude increases, the large-scale vortex structures are formed near the separation point and the flow structures become more organized and more regular, accompanying with the reduction of reattachment length. By further inverstigation of POD global entropy, it is seen that the reattachment length is closely linked to the degree of organization of the flow structures.es.s.

• Journal of Pharmaceutical Investigation
• /
• 제35권5호
• /
• pp.349-353
• /
• 2005

This study reports the pharmacokinetics of a novel histone deacetylase inhibitor, SD-0542, in rats after i..v. and oral administration. SD-0542 was injected intravenously at doses of 10, 20, and 40 mg/kg. The terminal elimination half-life $(t_{1/2})$, systemic clearance (Cl), and steady-state volume of distribution $(V_{ss})$ remained unaltered as a function of dose, with their values ranging from 2.0-2.5 hr, 157.2-214.1 ml/min/kg, and 11.1-17.5 L/kg, respectively, whereas, the initial serum concentration $(C_0)$ and AUC increased linearly as the dose was increased. Renal excretion of SD-0542 was minimal. Oral pharmacokinetic studies were conducted in rats at a dose of 20 mg/kg. The $T_{max}$, Cl/F, $V_{z}/F$, and $t_{1/2}$ were 2.0 hr, 92864 ml/min/kg, 16331 L/kg, and 2.0 hr, respectively. Taken together, SD-0542 showed linear pharmacokinetics over the i.v. bolus dose range studied. SD-0542 was poorly absorbed, with the absolute oral bioavailability of 0.9%.

• 한국환경과학회지
• /
• 제21권9호
• /
• pp.1069-1078
• /
• 2012

This study was performed to evaluate the asbestos exposure levels and to calculate excess lifetime cacer risks(ELCRs) in asbestos-containing buildings for maintenance and management. The range of airborne asbestos concentration of 33 buildings was 0.0018 ~ 0.0126 f/cc and one site exceeded indoor air-quality recommended limit 0.01 f/cc. And ELCRs based on US EPA IRIS(Integrated risk information system) model are 1.5E-06 ~ 3.9E-05 levels, and there was no site showed 1.0E-04 (one person per million) level or more, and 11 sites showed 1.0E-05 (one person per 100,000 people) level or more. To prevent the release of asbestos fibers, it needs operation and maintenance of asbestos-containing building materials, and there are some methods such as removal, repairment, enclosure and encapsulation. In conclusion, a risk-based air action level for asbestos in air is an appropriate metric for asbestos-containing building management.

• 인터넷정보학회논문지
• /
• 제24권6호
• /
• pp.1-11
• /
• 2023

Federated learning (FL) is a ground breaking machine learning paradigm that allow smultiple participants to collaboratively train models in a cloud environment, all while maintaining the privacy of their raw data. This approach is in valuable in applications involving sensitive or geographically distributed data. However, one of the challenges in FL is dealing with heterogeneous and non-independent and identically distributed (non-IID) data across participants, which can result in suboptimal model performance compared to traditionalmachine learning methods. To tackle this, we introduce FedGCD, a novel FL algorithm that employs Graph Neural Network (GNN)-based community detection to enhance model convergence in federated settings. In our experiments, FedGCD consistently outperformed existing FL algorithms in various scenarios: for instance, in a non-IID environment, it achieved an accuracy of 0.9113, a precision of 0.8798,and an F1-Score of 0.8972. In a semi-IID setting, it demonstrated the highest accuracy at 0.9315 and an impressive F1-Score of 0.9312. We also introduce a new metric, nonIIDness, to quantitatively measure the degree of data heterogeneity. Our results indicate that FedGCD not only addresses the challenges of data heterogeneity and non-IIDness but also sets new benchmarks for FL algorithms. The community detection approach adopted in FedGCD has broader implications, suggesting that it could be adapted for other distributed machine learning scenarios, thereby improving model performance and convergence across a range of applications.

• 한국식품영양학회지
• /
• 제23권3호
• /
• pp.332-341
• /
• 2010

통대추, 대추과육, 대추과즙에 소주와 효모를 사용하여 만든 대추 침출주와 대추 발효주의 제조 과정 중 성분과 품질을 비교한 결과는 다음과 같다. pH는 담금일에 4.93~5.42였으나, 제조 100일에는 3.66~4.97의 범위로 저하되었고, 시험구 중 발효주의 과즙구(WJ-F3)에서 3.66으로 가장 낮았다. 총 산은 담금 직후 0.67~1.01% 이었으나, 제조 100일에는 0.51~0.88%로 다소 저하되었으며, 발효주의 통대추구(WJ-F1)에서 총 산 함량이 타 시험구보다 높았다. 총 당과 환원당은 담금 일에 1.20~13.8%, 0.50~4.45% 이었고, 제조 100일에 총 당 1.53~4.52%, 환원당 1.75~3.82%로 제조 과정 중 저하되었으며 이들 당은 침출주의 통대추구가 높았다. 유리 당은 fructose, glucose, sucrose가 확인 되었다. 유리 당의 총량은 1.32~13.64% 이었고, 발효주의 과즙구(WJ-F3)에서 1.95~13.64%로 타 시험구보다 높았다. 대추주의 유리 당 중 glucose는 침출주에서, fructose는 60일 이후의 발효주에서 각각 높았다. 아미노태 질소는 담금 일에 검출되지 않았으나 제조 20일에 0.02~0.11%이었으며 제조 40일에 0.07~0.14%로 최대치를 보였다. 고형 분 함량은 담금 일에 2.68~7.76% 이었으나 제조 40일에 12.24~19.40%로 증가 되었고 이후 대체로 감소되어 제조 100일에 4.81~9.73%로 나타났다. 대추주의 색도 중 밝기(L 값)는 담금 일에 88.45~96.74이었으나 제조 40일까지는 다소 저하되었으며 제조 100일에는 92.62~100.45로 시험구에 따라서 약간 증가하였고 침출주의 과즙구에서 밝기가 가장 높았다. 적색도는 발효주의 과즙구만 양의 수치인 적색으로 측정되었고 이외의 시험구는 음의 수치인 녹색으로 나타났다. 황색도는 제조 20일과 40일에 강하였고 80일 이후는 퇴색으로 무색 또는 청색에 유사하였다. 발효주의 과즙구는 타 시험구보다 황색도가 높았다. 대추주의 전체적인 선호도는 침출주와 발효주간에 유의적 차이를 보였다.

• 한국통신학회논문지
• /
• 제12권1호
• /
• pp.36-49
• /
• 1987

하이브리드 모드 마이크로 스트립 線路에서 周波數의 函數인 實效誘電率 및 實效幅에 따른 正規化 位相速度와 特性 임피던스의 分散特性을 計算하기 爲한 Planar Waveguide 모델이 提示되었으며. Eeff(f)와 Weff(f)는 周波數에 따른 實驗關係式과 CAD를 目的으로 設定된 計算式을 利用하여 Planar Waveguide모델 計算에 適用하였고, 多樣한 比誘電率과 스트립 幅/基板 두께(W/h)는 $0.5$\leq$W/h\leq2.5의$ 比를 使用하여, 그 結果를 稱的値, Spectral domain 解析 및 實驗關係 結果 等과 比較하였다. 컴퓨터 시뮬레이션 結果, Planar Waveguide 모델을 利用할 境遇가 이미 發表된 바 있는 다른 方法보다 周波數가 增加함에 따라 周波數 別 正規化 位相速度는 1/ 의 값에 가장 接近하였고 特性 임피던스는 더욱 增加하였다. 또한, CAD를 目的으로 設定된 Eeff(f)를 本 提案 모델이 適用한 境遇가 實驗關係式을 利用한 境遇보다 더 좋은 結果를 얻을 수 있었다.

• 한국결정성장학회지
• /
• 제19권3호
• /
• pp.130-134
• /
• 2009

새로운 $CaZrO_3$, 축광성 형광체를 고온의 약한 환원 분위기에서 전통적인 고상반응법으로 합성하였다 광발광 분석 결과 $Tb^{3+}$ 이온을 첨가한 $CaZrO_3$ 축광성 형광체는 $^5D_3$, $^5D_4$ 에너지 준위에서 $^7F_1{\sim}^7F_6$ 준위로의 전이에 의해 황녹색의 발광을 나타내며, 고온의 질소분위기에서 합성한 경우의 축광성 형광체에 대한 스펙트럼의 주 피크는 $^5D_4{\rightarrow}^7F_5$ 전이에 의한 542 nm의 발광 피크가 생성되었다. $CaZrO_3:Tb^{3+}$ 축광성 형광체의 잔광 발광 스펙트럼은 좁은 영역의 546 nm의 피크가 강하게 생성되었다 잔광 휘도는 254 nm 자외선을 조사하고 전원을 끈 후에 측정하였으며, 녹황색의 축광성 형광체가 사람이 어두운 곳에서 인지 가능한 $0.32\;mcd/m^2$까지 8시간 지속됨을 관찰하였다.