• 한국재료학회지
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• 제9권5호
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• pp.520-527
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• 1999

열전 소결재 제조의 새로운 시도로, 분말의 압출과 소결을 동시에 할 수 있는 공정에 대하여 연구하였다. $(Bi,Sb)_2(Te,Se)_3$계 압출-소결재를 제조함에 있어 제조 변수를 적절히 조절하여 건전한 표면과 미세조직을 갖는 고밀도의 소결재를 얻을 수 있었다. p형 재료의 경우 Te 도핑량이 증가함에 따라 Seebeck 계수가 증가하였으며 3 at% Te을 첨가한 경우 상온에서의 열전 성능 지수가 $2.5\times10^{-3}/K$를 나타내었다. 한편 n형 재료의 경우 0.16 mol% $SbI_3$를 도핑한 시편에서 $1.8\times10^{-3}/K$의 열전 성능지수를 보였다. p형 및 n형 재료 모두 압출 방향에 수직한 방향보다 평행한 방향으로의 운반자 이동도와 열전 성능지수가 높게 나타났다.

• 공업화학
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• 제23권1호
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• pp.59-64
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• 2012

potassium persulfate (KPS)와 sodium dodecyl sulfonate (SDS)를 각각 개시제와 안정제로 사용한 유화중합에 의하여 인공먼지로 사용할 수 있는 polystyrene latex spheres (PLS)를 제조하였다. PLS입자의 크기를 조절하기 위한 변수로 반응온도와 개시제 및 안정제의 농도가 선택되었다. 반응온도의 증가에 따라 입자의 크기는 작아졌으며, KPS와 SDS의 농도를 변화시켜 PLS 입자의 크기 및 분포를 매우 미세하게 조절할 수 있었다. 본 연구에서 제조된 PLS입자는 변동계수 (CV) 값이 7% 이하인 단분산이며, 0.1~0.5 ${\mu}m$ 범위에 있어 인조 먼지로 사용하기에 적합한 것으로 밝혀졌다.

• 한국세라믹학회지
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• 제31권9호
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• pp.995-1004
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• 1994

Phase relation and microwave dielectric properties of the system BaO.(Nd1-xSmx)2O3.TiO2 (n=4, 5) were studied. With n=5 (1 : 1 : 5), Ba2Ti9O20 and TiO2 formed in case of X$\leq$0.7, and Ba2Ti9O20 and Sm2Ti2O7 formed at X=1.0 as the second phases dispersed in fine-grained orthorhombic matrix phase. With n=4 (1 : 1 : 4). on the contrary, only fine grains of an ortho-rhombic phase were observed irrespective of Nd/Sm ratio. The compositions of these two stable orthorombic phases having distinct lattic constants even with the same Nd/Sm ratio were estimated as 4BaO.5(Nd1-xSmx)2O3.18TiO2 and BaO.(Nd1-xSmx)2O3.4TiO2 with n=5 and n=4 in the system BaO.(Nd1-xSmx)2O3.TiO2, respectively. Consequently the composition BaO.(Nd1-xSmx)2O3.5TiO2 lies in the compatible triangle of 4BaO.5(Nd1-xSmx)2O3.18TiO2 and the second phases mentioned above. The microwave dielectric properties (~4 GHz) of BaO.(Nd1-xSmx)2O3.5TiO2 can be controlled effectively by adjusting Sm content : with increasing X from 0 to 0.7, both dielectric constant and the temperature coefficient of resonant frequency decreased monotonically from 82 to 65 and from 91 (ppm/$^{\circ}C$) to -19(ppm/$^{\circ}C$), respectively, while unloaded Q(Qo) remained constant at about 2,600.

• 한방비만학회지
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• 제14권1호
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• pp.29-35
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• 2014

Objectives: This study was to investigate how body-shape perception could influence to weight control practice both in normal and obese group. Methods: We used 2012 Korea National Health and Nutrition Examination Survey to analysis 1) weight control practices of population; 2) consistency between body-shape perception and body mass index; 3) comparison weight control practices between normal group and body mass index (BMI) obese group in perceptional obese group; 4) odds ratio of BMI obese group using herbal drugs for weight control practice in perceptional obese group. Results: We found that study population tends to choose exercise, dietary restriction, meal skip, health functional food, one-food, drug, herbal drug, fasting and self-medication in order of frequency to control weight. The agreement between body-shape perception and BMI within obese group was approximately 64% with 0.40 of Cohen's Kappa coefficient, ranging from 0.384 to 0.423. Within perceptional obese group, choosing each weight control practice methods ratios between normal BMI group and obese BMI group were not significantly different. Within perceptional obese group, obese BMI group showed significant odds ratio (2.58, 95% confidence intervals, 1.38~4.85) than normal BMI group in choosing herbal medication for weight loss when adjusting other variables. Conclusions: We concluded that body-shape perception might be an important factor for choosing weight control program, and roles of Korean medical doctors thought to be enhanced for using herbal medication for weight loss.

• Bulletin of the Korean Chemical Society
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• 제28권8호
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• pp.1375-1382
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• 2007

A column preconcentration method with pulverized Amberlite XAD-4 loaded with bismuthiol I (BI) has been developed for the determination of trace Cd(II) and Cu(II) in various real samples by flame atomic absorption spectrophotometry. Various experimental conditions, such as the size of XAD-4, adsorption flow rate, amount of bismuthiol I, stirring time for adsorbing bismuthiol I on XAD-4, pH of sample solution, amount of XAD-4- BI, desorption solvent, and desorption flow rate, were optimized. Also, the adsorption capacity and the adsorption rate of Cd(II) and Cu(II) on XAD-4-BI were investigated. The interfering effects of various concomitant ions were investigated, Bi(III), Sn(II) and Fe(III) were found to affect the determination. But the interference by these ions was completely eliminated by adjusting the amount of XAD-4-BI resin to 0.70 g, although the adsorption flow rate was slower. For Cd(II) our proposed technique obtained a dynamic range of 0.5-40 ng mL-1, a correlation coefficient (R2) of 0.9913, and a detection limit of 0.3 ng mL-1. For Cu(II), the corresponding values were 2.0-120 ng mL-1, 0.9921 and 1.02 ng mL-1. To validate this proposed technique, the aqueous samples (stream water, reservoir water, tap water and wastewater), the diluted brass sample and the plastic sample, as real samples, were used. Recovery yields of 91-103% were obtained. These measured data were not different from ICP-MS data at 95% confidence level. Our proposed method was also validated using rice flour CRM (normal, fortified) samples. From the results of our experiment, we found that the technique we present here can be applied to the determination of Cd(II) and Cu(II) in various real samples.

• Korean Chemical Engineering Research
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• 제56권2호
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• pp.191-203
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• 2018

이 연구는 각각 크기와 재질이 다른 3 가지 종류의 분쇄 매체를 이용하여 회전속도와 밀링 시간의 따른 구리 (Cu) 분말의 형상변화의 과정에 미치는 영향을 관찰하고, 볼 움직임의 DEM시뮬레이션을 행하였다. 전동볼밀에서 볼 움직임의 3차원 시뮬레이션을 통해 분쇄 메커니즘을 규명하기 위하여 분쇄매체의 힘, 운동에너지, 매체 운동속도 등을 계산하였다. 시뮬레이션에서는 회전속도, 볼 재질, 운동속도, 마찰계수 등을 실제 실험조건과 동일하게 조건을 맞추어 투입되는 에너지의 변화량도 계산하였다. 주사전자현미경 결과를 살펴보면 볼 직경이 작을 때 입자형상이 불규칙한 형태에서 구형 형태로 변화하는 것을 알 수 있었다.

• 대한예방한의학회지
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• 제14권1호
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• pp.49-58
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• 2010

Objective : The purpose of this study is to examine safety of herbal medicine on liver function and compare with western medicine. Method : 303 subjects of skin disease(vitiligo and psoriasis) were chosen at a local oriental medical clinic, and tested with a spot liver function test from Sept 1, 2006 to Dec 31, 2006. Subjects were grouped into untreated, herbal medicine, western medicine, and combination group by treatment record. Total bilirubin, AST, ALT and LDH was compared in each group, odds ratio and regression coefficient was calculated. Results : Subjects comprised of 116 individuals receiving western medication(38.28%), 54 receiving herbal medication(17.82%), 107 receiving combined forms of medication(35.31%), and 26 individuals without any types of medication(8.58%). With the mean age of 37.0 yr. 204 were male(67.3%), 99 were female(32.7%). Comparing variables of liver functions, there was no significant difference between the control and experiment groups. After adjusting potential confounders, monthly $\beta$(SE) of multiple regression -0.009~0.000 for the herbal group, -0.005~0.000 for the western group, and -0.001~0.001 for the combination group. No significant difference between the groups. OR of T-bilirubin were 1.02, 1.05, and 1.04. AST were 0.92, 0.94, and 0.98. ALT were 0.85, 0.99, and 0.97. LDH were 0.96, 1.06, 1.00 for the herbal, western, and combination group, respectively. Conclusion : Comparing with western medication, herbal medication did not cause special ill-effect on the liver function based on liver function tests.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권4호
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• pp.1845-1865
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• 2019

Current Internet is designed by lots of service providers with different objects and policies which make the direct deployment of radically new architecture and protocols on Internet nearly impossible without reaching a consensus among almost all of them. Network virtualization is proposed to fend off this ossification of Internet architecture and add diversity to the future Internet. As an important part of network virtualization, virtual network embedding (VNE) problem has received more and more attention. In order to solve the problems of large embedding cost, low acceptance ratio (AR) and environmental adaptability in VNE algorithms, cognitive method is introduced to improve the adaptability to the changing environment and a cognitive virtual network embedding algorithm based on weighted relative entropy (WRE-CVNE) is proposed in this paper. At first, the weighted relative entropy (WRE) method is proposed to select the suitable substrate nodes and paths in VNE. In WRE method, the ranking indicators and their weighting coefficients are selected to calculate the node importance and path importance. It is the basic of the WRE-CVNE. In virtual node embedding stage, the WRE method and breadth first search (BFS) algorithm are both used, and the node proximity is introduced into substrate node ranking to achieve the joint topology awareness. Finally, in virtual link embedding stage, the CPU resource balance degree, bandwidth resource balance degree and path hop counts are taken into account. The path importance is calculated based on the WRE method and the suitable substrate path is selected to reduce the resource fragmentation. Simulation results show that the proposed algorithm can significantly improve AR and the long-term average revenue to cost ratio (LTAR/CR) by adjusting the weighting coefficients in VNE stage according to the network environment. We also analyze the impact of weighting coefficient on the performance of the WRE-CVNE. In addition, the adaptability of the WRE-CVNE is researched in three different scenarios and the effectiveness and efficiency of the WRE-CVNE are demonstrated.

• Clinical and Experimental Reproductive Medicine
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• 제46권3호
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• pp.125-131
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• 2019

Objective: To investigate serum 25-hydroxyl vitamin D (25(OH)D) and vitamin D-binding protein (VDBP) concentrations in women with endometriosis according to the severity of disease. Methods: Women with mild endometriosis (n = 9) and advanced endometriosis (n = 7), as well as healthy controls (n = 16), were enrolled in this observational study. Serum total 25(OH)D concentrations were analyzed using the Elecsys vitamin D total kit with the Cobas e602 module. Concentrations of bioavailable and free 25(OH)D were calculated. Concentrations of VDBP were measured using the Human Vitamin D BP Quantikine ELISA kit. Variables were tested for normality and homoscedasticity using the Shapiro-Wilk test and Leven F test, respectively. Correlation analysis was used to identify the variables related to total 25(OH)D and VDBP levels. To assess the effects of total 25(OH)D and VDBP levels in the three groups, multivariate generalized additive modeling (GAM) was performed. Results: Gravidity and parity were significantly different across the three groups. Erythrocyte sedimentation rate (ESR) and CA-125 levels increased as a function of endometriosis severity, respectively (p= 0.051, p= 0.004). The correlation analysis showed that total 25(OH)D levels were positively correlated with gravidity (r = 0.59, p< 0.001) and parity (r = 0.51, p< 0.003). Multivariate GAM showed no significant relationship of total 25(OH)D levels with EMT severity after adjusting for gravidity and ESR. However, the coefficient of total 25(OH)D levels with gravidity was significant (1.87; 95% confidence interval, 0.12-3.63; p= 0.040). Conclusion: These results indicate that vitamin D and VDBP levels were not associated with the severity of endometriosis.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권7호
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• pp.2631-2649
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• 2021

Device-to-Device (D2D) communication is one of the enabling technologies for 5G networks that support proximity-based service (ProSe) for wireless network communications. This paper proposes a power control algorithm based on the Nash equilibrium and game theory to eliminate the interference between the cellular user device and D2D links. This leadsto reliable connectivity with minimal power consumption in wireless communication. The power control in D2D is modeled as a non-cooperative game. Each device is allowed to independently select and transmit its power to maximize (or minimize) user utility. The aim is to guide user devices to converge with the Nash equilibrium by establishing connectivity with network resources. The proposed algorithm with pricing factors is used for power consumption and reduces overall interference of D2Ds communication. The proposed algorithm is evaluated in terms of the energy efficiency of the average power consumption, the number of D2D communication, and the number of iterations. Besides, the algorithm has a relatively fast convergence with the Nash Equilibrium rate. It guarantees that the user devices can achieve their required Quality of Service (QoS) by adjusting the residual cost coefficient and residual energy factor. Simulation results show that the power control shows a significant reduction in power consumption that has been achieved by approximately 20% compared with algorithms in [11].