• Journal of IKEEE
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• v.19 no.1
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• pp.33-40
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• 2015

Inverse problem in electrical impedance tomography (EIT) is highly ill-posed therefore prior information is used to mitigate the ill-posedness. Regularization methods are often adopted in solving EIT inverse problem to have satisfactory reconstruction performance. In solving the EIT inverse problem, iterative Gauss-Newton method is generally used due to its accuracy and fast convergence. However, its performance is still suboptimal and mainly depends on the selection of regularization parameter. Although, there are few methods available to determine the regularization parameter such as L-curve method they are sometimes not applicable for all cases. Moreover, regularization parameter is a scalar and it is fixed during iteration process. Therefore, in this paper, a novel method is used to determine the regularization parameter to improve reconstruction performance. Conductivity norm is calculated at each iteration step and it used to obtain the regularization parameter which is a diagonal matrix in this case. The proposed method is applied to human thorax imaging and the reconstruction performance is compared with traditional methods. From numerical results, improved performance of proposed method is seen as compared to conventional methods.

• The Transactions of the Korea Information Processing Society
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• v.5 no.1
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• pp.137-148
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• 1998

In this paper, we proposed the algorithm to run MCS protocol, the core technology of T.120 series, over Multicast Transport Protocol and described an implementation architecture we proposed. An algorithm implemented can utilize some functions of Multicast Transport Layer fully, keeping the backward compatibility with the existing Mes. In order to do so, when a connection sets up, the Multicast Transport Layer looks into whether that of the peer entity does have multicast functionality. If it has, multicast functionality can be used. Unless, it can not. We are going to contribute these technologies to IMTC organizing the interoperability test of T.l20 series.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.10
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• pp.925-931
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• 2010

The paper describes a Large Eddy Simulation (LES) study of turbulent flow around a cavity. A series of three-dimensional cavities placed in a turbulent boundary layer are simulated at a Reynolds number of $1.0{\times}10^5$ by considering U and h, which represent the velocity at the top and the depth of the cavity, respectively. In order to obtain the appropriate solution for the filtered Navier-Stokes equation for incompressible flow, the computational mesh forms dense close to the wall of the cavity but relatively coarse away from the wall; this helps reduce computation cost and ensure rapid convergence. The Boussinesq hypothesis is employed in the subgrid-scale turbulence model. In order to determine the subgrid-scale turbulent viscosity, the Smagorinsky-Lilly SGS model is applied and the CFL number for time marching is set as 1.0. The results show the flow variations inside cavities of different sizes and shapes.

• Journal of Applied Biological Chemistry
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• v.60 no.1
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• pp.61-68
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• 2017

In this study, extracts from Caryopteris incana Miq. (C. incana) were investigated to assess anti-oxidation, skin-whitening and anti-wrinkle activity. The total phenolic compounds of C. incana extracts with water and 80 % ethanol showed 7.69 and 12.50 mg/g respectively. Antioxidation activity of C. incana extracts was measured by using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), protection factor (PF), and Thiobarbituric acid reactive substances (TBARs). At concentration of $200{\mu}g/mL$, the DPPH free radical scavenging activity of water and ethanol extracts were 84 and 92 %, respectively. ABTS radical scavenging activity of water and ethanol extracts were both at approximately 99 %. Antioxidant PF of water and ethanol extracts were 1.56 PF and 1.67 PF, respectively. The TBARs of water and ethanol extracts were 62 and 82 %, respectively. In anti-wrinkle and skin-whitening activity, 80 % ethanol extract had more outstanding effect than water extract at concentration of $200{\mu}g/mL$. The levels of elastase and collagenase inhibitory activity related with anti-wrinkle were 58 and 89 % in ethanol extract. The tyrosinase inhibitory activity related with skin-whitening was 13 % in ethanol extract. The astringent effect of ethanol extract was 50 %. Throughout the results, C. incana extracts showed an excellent effect on anti-oxidation, skin-whitening and anti-wrinkle activity. Therefore, C. incana extracts can be used as a new material for cosmetics.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.3
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• pp.333-341
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• 2016

This study examined the beauty food activities of water and ethanol extracts from Tetragonia tetragonioides. Content of phenolic compounds extracted with water and 50% ethanol extracts were 3.29 mg/g and 4.14 mg/g, respectively. 1,1-Diphenyl-2-picrylhydrazyl free radical scavenging activities of water and ethanol extracts were 98.45% and 91.20%, respectively, at $200{\mu}g/mL$ of phenolics. 2,2'-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical decolorization activity was 97.28% for water extracts and 97.83% for ethanol extracts at $100{\mu}g/mL$ of phenolics. Antioxidant protection factor (PF) was 1.77 PF for water and ethanol extracts at $200{\mu}g/mL$ of phenolics. Thiobarbituric acid reactive substances of water and ethanol extracts were 94.77% and 95.64%, respectively, at $100{\mu}g/mL$ of phenolics. Tyrosinase inhibitory activity, which is related to skin-whitening, was confirmed to be 34.96% for ethanol extracts at $200{\mu}g/mL$ of phenolics. Elastase inhibitory activity and anti-wrinkle effect of 50% ethanol extracts were 78.9% at $200{\mu}g/mL$ of phenolics. Collagenase inhibitory activity of ethanol extracts was 61.29% at $200{\mu}g/mL$ of phenolics. Astringent effect was not detected in water extracts but was 7.82% for 50% ethanol extracts at $200{\mu}g/mL$ of phenolics. Hyaluronidase inhibitory activity as a measure of anti-inflammation was confirmed to be 81.04% for water extracts at $200{\mu}g/mL$ of phenolics. Based on these results, Tetragonia tetragonioides extracts can be used as a functional material and functional beauty food with antioxidant effects.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1999.11a
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• pp.32-37
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• 1999

본 연구는 컨조인트 분석기법을 이용하여 의자의 물리적 적합도를 분석, 평가하여 사용자가 선호하는 최적의 의자를 제시하고자 하는데 목적이 있다. 컨조인트 분석기법은 Marketing 분야에서 주로 많이 쓰여온 분석 방법으로서 제품의 중요한 속성들을 찾아내어 다양한 종류의 제품들에 대한 고객의 선호도를 분석하는 방법이다. 이러한 컨조인트 분석기법은 제품개발과 평가의 측면에서 매우 큰 가능성이 있음에도 불구하고 마켓팅 이외의 분야에서는 거의 적용되자 않고 있는 실정이다. 따라서 본 연구에서는 의자의 물리적 적합성 연구에 이 컨조인트 분석을 이용하여 그 적용의 가능성을 알아보고자 하였다. 또한 이러한 적합성 연구에 컨조인트 분석기법이 타당한 분석기법인지 비교하기 위해 분산분석의 기법도 병행하여 실시하였다. 문헌 조사와 전문가 의견 수렴을 통하여 선행연구에서 추출된 의자의 물리적 적합도 요소인 안정성, 여유성, 적합성, 안락성등 4개의 적합도 요소를 채택하여 종속변수로 사용하였다. 또한 의자 자체의 설계 요소에 해당하는 휴먼인터페이스 요소(HIE)는 높이 조절 여부, 팔걸이 유무, Tilting 유무의 3가지 속성을 선택하여 독립변수로 사용하였다. 분석에 사용된 의자는 각 속성을 특징적으로 대표하는 8개의 의자들로서 구성하였고 63명의 피험자를 사용하여 실험하였다. 분석의 결과는 안정성에 가장 큰 영향을 주는 속성은 높이조절(HC)로서 남자와 여자 모두 높이조절 기능이 없을 때 안정성을 느낀다는 결과가 나왔다. 여유성에 영향을 주는 가장 큰 요인은 남자는 높이조절 기능이 있을 때, 여자는 팔걸이가 있을 때 여유성이 있다고 판단하였으며, 인체적합성에 영향을 주는 요인은 남자와 여자 모두 Tilting 기능이, 안락성에 영향을 주는 주요인은 남자는 Tilting 기능이 있을 매, 여자는 높이조절 기능이 있을 때인 것으로 나타났다.감, 강연성, 회복성, 수분특성, 밀도감이었으며, 요인들로 설명되는 누적분산값은 67.18%였다.주관적 평가의 결과와 객관적 평가 결과를 이용해 마직물의 태를 평가하는 산출식을 제시하였다. 태 평가치의 경우 16가지 특성치를 모두 넣는 방법과 stepwise 방법, 또 Kawabatark 사용한 순차적 군 회귀법의 세가지 방법의 회귀식 중 16가지 특성치를 모두 넣는 방법의 결정계수가 가장 높았다.tosterone농도는 107.7$\pm$12.0 pmol／l이었고, 남성의 타액내 농도는 274.2$\pm$22.1 pmol／l이었다. 이상의 결과로 보아 본 연구에서 정립된 EIA 방법은 RIA를 대신하여 소규모의 실험실에서도 활용할 수 있을 것으로 사려된다.또한 상실기 이후 배아에서 합성되며, 발생시기에 따라 그 영향이 다르고 팽창과 부화에 관여하는 것으로 사료된다. 더욱이, 조선의 ${\ulcorner}$구성교육${\lrcorner}$이 조선총독부의 관리하에서 실행되었다는 것을, 당시의 사범학교를 중심으로 한 교육조직을 기술한 문헌에 의해 규명시켰다.nd of letter design which represents -natural objects and was popular at the time of Yukjo Dynasty, and there are some documents of that period left both in Japan and Korea. "Hyojedo" in Korea is supposed to have been influenced by the letter design. Asite- is also considered to have been "Japanese Letter Jobcheso." Therefore, the purpose of

• Water for future
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• v.21 no.1
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• pp.67-76
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• 1988

Analyzed was the circulation phenomena in the open channel with sudden expansion, by applying the Galerkin's finite element method to the depth-averaged 2-dimensional continuity and momentum equations. Wave tests were done in the simplified channel in order to review the validity of this newly developed model and the computed results were within 0.5% of $L_2$-norm error, and application of this model to the simulation of simplified dam-break gave very close results compared with the analytical solution, thus, it can be concluded that this model is valid and efficient. The main flow in the expanded channel was defined as a new initial condition with given velocity and the flow in the expanded portion was at rest in simulating the circulation, and besides the Neumann's condition the slip boundary condition for lateral wall was found to be proper condition than the no-slip condition. It can be concluded, from the numerical tests in the sudden expension, that the circulating phenomena depend mainly on the convective inertia and the effect of turbulence due to bottom shear and lateral shear is insignificant.

• Microbiology and Biotechnology Letters
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• v.47 no.1
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• pp.148-157
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• 2019

A 70% ethanol extract of Erigeron annuus (L.) Pers. was investigated for its whitening activity for application as a functional ingredient in cosmetic products. At the E. annuus extract concentration of $100{\mu}g/ml$, the electron-donating ability was found to be 67.83%, the tyrosinase inhibitory effect (related to skin-whitening) was 69%, the elastase inhibitory effect (related to skin-wrinkling) was 69%, and the astringent effect was 80%. The $ABTS^+$ radical-scavenging ability was 87% at the $500{\mu}g/ml$ concentration. In the cell viability test measured on melanoma cells, 96% of the cells treated with $100{\mu}g/ml$ of the extract were viable. According to the western blot results, the protein expression of the microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2 was decreased by 60.22%, 47.83%, 54.79%, and 67.88%, respectively, at the extract concentration of $100{\mu}g/ml$. The protein expression of phosphorylated extracellular signal regulated kinase (p-ERK) and phosphorylated cAMP response element-binding protein (p-CREB) was decreased with increasing concentrations of the extract. Reverse transcription-polymerase chain reaction of the extract showed that the mRNA expression of MITF, tyrosinase, TRP-1, and TRP-2 was decreased by 86.51%, 85.22%, 74.26%, and 66.66%, respectively, at $100{\mu}g/ml$ extract concentration. The findings suggest that the 70% ethanol extract from E. annuus (L.) Pers. has potential as a cosmeceutical ingredient with whitening effect.

• Food Science and Preservation
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• v.20 no.2
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• pp.234-241
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• 2013

The phenolic compounds of water extracts from Prunella vulgaris were highest at 9.25 mg/g, respectively, when various extraction solvents were used. The optimum condition for extracting phenolic compounds from Prunella vulgaris was extraction in water for 18hr. The DPPH-scavenging activities of Prunella vulgaris were highest at the water extracts. The ABTS radical cation decolorization was higher than 40% in the range of 0~100% ethanol extract section. The antioxidant protection factor on the lipophilic phenolic metabolites was shown to be 1.1 PF in the water extracts from Prunella vulgaris. The TBARS was lower than the control ($0.53{\mu}M$) in all the sections. The tyrosinase inhibitory effect, which is related to skin whitening, was above 40%, and for the anti-wrinkle effect, the elastase inhibition activity was above 40% at 0.2 mg/mL. The astringent effect of the Prunella vulgaris 40% ethanol extracts was 98.1% at 1 mg/mL. As a result, it can be concluded that Prunella vulgaris has the potential to be used as a cosmetic material.

• The Korean Journal of Financial Management
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• v.21 no.1
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• pp.149-181
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• 2004

In this study we perform empirical tests using KOSPI return to investigate the existence of nonlinear characteristics in the generating process of stock returns. There are three categories in empirical tests; the test of nonlinear dependence, nonlinear stochastic process and nonlinear deterministic chaos. According to the analysis of nonlinearity, stock returns are not normally distributed but leptokurtic, and appear to have nonlinear dependence. And it's decided that the nonlinear structure of stock returns can not be completely explained using nonlinear stochastic models of ARCH-type. Nonlinear deterministic chaos system is the feedback system, which the past incidents influence the present, and it is the fractal structure with self-similarity and has the sensitive dependence on initial conditions. To summarize the results of chaos analysis for KOSPI return, it is the persistent time series, which is not IID and has long memory, takes biased random walk, and is estimated to be fractal distribution. Also correlation dimension, as the approximation of fractal dimension, converged stably within 3 and 4, and maximum Lyapunov exponent has positive value. This suggests that chaotic attractor and the sensitive dependence on initial conditions exist in stock returns. These results fit into the characteristics of chaos system. Therefore it's decided that the generating process of stock returns has nonlinear deterministic structure and follow chaotic process.