• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.975-982
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• 2005

The purpose of the Gage R&R study is to determine whether a measurement system is adequate for monitoring a process. If the measurement system variation is small relative to the process variation, then the measurement system is deemed 'adequate'. The sources of variation associated with the measurement system are compared using an analysis of variance (ANOVA) model, in general. A typical ANOVA model used in a standard Gage R&R study is the two-factor random effect model. Then, the ANOVA partitions the total variation into three categories: repeatability, reproducibility, part variation. However, if the process variation possesses the between group variation, within group variation, and within-part variation, these variations can cause the measurement system evaluation to provide misleading results. That is, in the standard Gage R&R study these variations affect the estimate of repeatability, reproducibility, or both. This paper presents a four-factor nested factorial ANOVA model which explicitly considers these variations for the Gage R&R study. The variance component estimates are derived by setting the EMS equations equal to the corresponding mean square from the ANOVA table and solving. And the proposed model is compared with the standard Gage R&R model.

• Journal of Technology Innovation
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• v.13 no.2
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• pp.207-222
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• 2005

A prerequisite for making R&D more productive is to able to measure its productivity. Most of the previous studies on this topic have attempted to measure R&D productivity at the firm or industry levels. In this study, however, R&D productivity is measured at the national level to provide R&D policy implications, particularly for Asian countries. Contrary to the previous studies where total factor productivity was adopted, this study employs the data envelopment analysis (DEA) approach to measure R&D productivity. DEA is a multi-factor productivity analysis model for measuring the relative efficiency of each Decision Making Unit (DMU). In addition to the basic DEA model that includes all inputs and outputs, five additional models are constructed by combining single input with all outputs and single output with all inputs in order to measure specialized R&D efficiency. In this study, the twenty-seven countries are classified into four clusters based on the output-specialized R&D efficiency: inventors, merchandisers, academicians, and duds. Then, the characteristics of the Asian countries with respect to R&D efficiency are identified. It is found that Singapore ranks high in total efficiency, and Japan in patent-oriented efficiency. Meanwhile, China, Korea, and Taiwan are found to be relatively inefficient in R&D. We expect that the findings from this study will be able to provide directions for R&D policy-making of the Asian countries.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.4
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• pp.80-88
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• 1997

An experimental investigation of the fatigue through crack growth behavior under simple stepped variable loading condition has been performed using Al7075-T651. Experiments were carried out by using cantilever bending type specimens, with chevron notches on a small electro-magnetic test machine. Tensile overloads have a retarding effect on the fatigue crack growth rates, therefore tensile overloads were used for the beneficial effect on the fatigue life. While in most cases compressive overloads have only a vanishing effect on crack growth rates, some experiments with single edge crack tension specimens reveal a marked growth retardation. The stress ratios used in this investigations varies from R=0.32 to 0.81, from R=0.04 to 0.76, from R=-0.15 to 0.73, and from R=-0.33 to 0.68 and the peak load for each case was not varied. The crack growth and crack closure were measured by Kikukawa's compliance method with a strain gauge mounted on the backside of each specimens. The results obtained are as follows. When the stepped variable load was applied, the smaller the stress ration was, the larger the delayed retardation of the crack growth rate was. The fatigue crack growh rate data obtained for through cracks were plotted well against the effective stress intensity factor range from 4.0 to 20.0MP{a^{SQRT}m}. It was found that the effective stress intensity factor range ratio was related well to the opening stress intensity factor, the maximum stress intensity factor, and crack length.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 1998.07a
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• pp.32-33
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• 1998

생물체에서 유전외적 변형의 하나인 DNA 메틸화는 cis-acting factor의 조성변화를 통하여 세포특이 유전자의 발현과 virus latency, genomic imprinting, mutagenesis등과 같은 생물학적 효과를 나타내는 것으로 알려져 있다.(reviewed by Olle Heby, 1995). 5-azaCR, 5-azaCdR 그리고 6-azaCR의 처리결과는 배아자체의 DNA 메틸화의 유지가 정상발생에 필수적임을 알 수 있으며, 메틸화에 의한 배아발생 조절기작이 존재함을 암시하고 있다. 이러한 과정에서 5-azaCR과 5-azaCdR은 서로다른 경로를 통하여 배아발생에 관여함을 보여주었다. 즉, 5-azaCdR은 주로 DNA에 incorporation되어 작용하는 것으로 여겨지며, 5-azaCR은 DNA 보다는 RNA에 incorporation되어 작용하는 것으로 나타났다. 그리고, 비록 소수의 유전자만이 조사되었지만, 5-azaCdR의 incorporation에 의한 cis-acting factor의 변화는 전사인자인 c-myc proto-oncogene과 fluid 수송에 관여하는 $Na^{+}$, $K^{+}$-ATPase 유전자의 전사를 억제하지 않았다. 반면, 5-azaCR의 RNA로의 incorporation은 전사인자인 c-myc proto-oncogene의 전사를 억제하였으며, 연이어 fluid 수송에 관련되어있는 $Na^{+}$, $K^{+}$-ATPase 유전자의 전사를 억제하였다. 이것은 아마도 RNA로 incorporation된 5-azaCR은 RNA의 post-transcriptional processing에 영향을 주어 trans-acting factor의 조성을 변화, 전사적 repression을 유발한 것으로 사료된다. 생쥐 착상전 초기배아에서 DNA 메틸화는 short-term하게는 cis-acting factor로써 전사적 수준에서 유전자발현 조절하며, 그리고 유전자발현을 통하여 long-term하게는 배아발생에 관여 할 것이라고 사료된다.

• Kyungpook Mathematical Journal
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• v.63 no.4
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• pp.551-560
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• 2023

In this paper we consider a more general class of centralizers called I-centralizers. More precisely, given a prime ideal P of an arbitrary ring R we establish a connection between certain algebraic identities involving a pair of P-left centralizers and the structure of the factor ring R/P.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2331-2338
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• 1994

Experimental conditions of the optical shadow methods of caustics for measurement of the stress intensity factor and the J-integral in various materials(polycarbonate, PMMA, Al 5586D) are investigated. The necessary experimental requirements toe determine accurate values of the stress intensity factors and the J-integrals are described. The ratio of $r_o$ (radius of initial curve) to $r_p$ (plastic zone size) is selected as a parameter to verify the experimental limitation of the method of caustics in determination of fracture parameters. In this study, transmission caustics method was used for compact tension specimens made of polycarbonate and PMMA. while reflection caustics method was applied to c-shaped tension specimen made of Al 5586D. The appropriate ranges of $r_o/r_p$ tp determine accurate values of stress intensity factors were found to be 1.5~1.8. Existing experimental results have been obtained mainly by changing $r_p$ with different loads in $r_o/r_p$. However, in this study we could obtain varying $K_{caus}/K_{th}$ over the wide range of $r_o/r_p$ at fixed load conditions with newly designed optical arrangement. Thus, we could find the range in which theoretical and experimental results agree well each other by changing $r_o$ values only. In Al 5586D specimen, experimental caustics were located inside of the plastic zone, and $K_{caus}/K_{th}$ were found to be not unity in this range. It is found that $J_{caus}/J_{th}=1{\;}with{\;}r_o/t{\geq}0.8$ and the experimental plastic zone includes the contours of caustics.

• Asia Pacific Journal of Business Review
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• v.1 no.2
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• pp.37-62
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• 2017

To analyze the effects of R&D expenditure on the firm value of Korean firms, we classified portfolios based on R&D activity levels. After that, we conducted a time-series analysis to assess excess returns from the portfolios. To carry out such an analysis, an empirical analysis of excess returns in the capital market was performed by using the monthly earning rate of stocks from 2000 to 2013. The purpose of this research is to provide basic data on investment to stakeholders in the capital market by analyzing the effects of R&D on the firm value and to overcome scholarly limitations by offering a new model of analysis. The criteria for classifying the portfolios were based on R&D expenditure levels. The analysis models follow the Fama-French Three-Factor Model and the Carhart Four-Factor Model. The analyses results are as follows. Extrapolating monthly profit rates based on R&D expenditure levels, portfolios with low R&D expenditures showed higher earning rates than those with high R&D expenditures. This suggests that high R&D expenditures did not translate into high earning rates. The investor depreciates the R&D expenditures related profitability and the possibility of success in the market, leading to falls in stock prices and a failure to give a positive effect on the firm value. Our research differs from the previous investigations as we carried out an empirical analysis based on the actual investors' attitudes about R&D expenditures and how these can generate excess earnings. Our research results show that the data related to R&D expenditure are not reflected fully in the market.

• Biomolecules & Therapeutics
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• v.22 no.6
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• pp.547-552
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• 2014

Ribes fasciculatum var. chinense MAX. (R. fasciculatum) has traditionally been used in Korea to treat inflammatory diseases. However, the exact mechanism that accounts for the anti-inflammatory effect of R. fasciculatum is not completely understood. We aimed to ascertain the pharmacological effects of R. fasciculatum on both compound 48/80- or histamine-induced scratching behaviors and 2, 4-dinitrochlorobenzene (DNCB)-induced atopic dermatitis (AD) in mice. Additionally, to find a possible explanation for the anti-inflammatory effects of R. fasciculatum, we evaluated the effects of R. fasciculatum on the production of inflammatory mediators in LPS-stimulated macrophage cells. Treatment of R. fasciculatum significantly reduced compound 48/80- or histamine-induced the pruritus in mice. R. fasciculatum attenuated the AD symptoms such as eczematous, erythema and dryness and serum IgE levels in AD model. Additionally, R. fasciculatum inhibited the production of tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) and interleukin-6 (IL-6). The maximal rates of TNF-${\alpha}$ and IL-6 inhibition by R. fasciculatum (1 mg/ml) were approximately 32.12% and 46.24%, respectively. We also showed that R. fasciculatum inhibited the activation of nuclear factor-kappa B in LPS-stimulated macrophages. Collectively, the findings of this study provide us with novel insights into the pharmacological actions of R. fasciculatum as a potential molecule for use in the treatment of allergic inflammatory diseases.

• Journal of Biomedical Engineering Research
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• v.32 no.3
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• pp.245-250
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• 2011

Parallel imaging technique can provide several advantages for a multitude of MRI applications. Especially, in SENSE technique, sensitivity maps were always required in order to determine the reconstruction matrix, therefore, a number of difference approaches using sensitivity information from coils have been demonstrated to improve of image quality. Moreover, many filtering methods were proposed such as adaptive matched filter and nonlinear diffusion technique to optimize the suppression of background noise and to improve of image quality. In this study, we performed SENSE reconstruction using computer simulations to confirm the most suitable method for the feasibility of filtering effect and according to changing order of polynomial fit that were applied on variation of spatial resolution of sensitivity map. The image was obtained at 0.32T(Magfinder II, Genpia, Korea) MRI system using spin-echo pulse sequence(TR/TE = 500/20 ms, FOV = 300 mm, matrix = $128{\times}128$, thickness = 8 mm). For the simulation, obtained image was multiplied with four linear-array coil sensitivities which were formed of 2D-gaussian distribution and the image was complex white gaussian noise was added. Image processing was separated to apply two methods which were polynomial fitting and filtering according to spatial resolution of sensitivity map and each coil image was subsampled corresponding to reduction factor(r-factor) of 2 and 4. The results were compared to mean value of geomety factor(g-factor) and artifact power(AP) according to r-factor 2 and 4. Our results were represented while changing of spatial resolution of sensitivity map and r-factor, polynomial fit methods were represented the better results compared with general filtering methods. Although our result had limitation of computer simulation study instead of applying to experiment and coil geometric array such as linear, our method may be useful for determination of optimal sensitivity map in a linear coil array.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.2
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• pp.340-347
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• 1994

The specimens used in this study were obtained from patients with primary gastric carcinoma and adjacent non-malignant mucosa from the same patients. Using the techniques of immunocyto chemicstry and in situ hybridization, transforming growth $factor-{\alpha}(TGF-{\alpha})$ and epiderimal growth factor receptor (EGF-R) nRNAs were identified. $TGF-{\alpha}$ was observed in macrophages and dividing tumor cells but, not in normal cells. EGF-R was observed both in malignant and non-malignant gastric tissues. Although normally, $TGF-{\alpha}$ is not seen in normal gastric tissues, $TGF-{\alpha}$ was discovered in the adjacent non-malignant tissue of histolgically normal, which strongly suggest that $TGF-{\alpha}$ is involved in the differentiation of cancer cells. Immunocytochemicstry using EMB-11 antibody identified the existence of macrophages which express $TGF-{\alpha}$ and EGF-R mRNA. Protein products of EGF-R was identfified using monoclonal antibody. Cancer cells were also identified in the non-malignant normal tissues by the method of immunocytochemicstry using carcino embryonic antigen (CEA)antibody. It is considered that the activity of $TGF-{\alpha}$ increased as tumor cell prolifierates. Immunocytochemistry and in situ hybridization techniques can be used to diagnose gastric cancer along with the use of ${\alpha}-feto$ protein and CEA.