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        검색결과 2,998

        2561.
        2017.12 KCI 등재 서비스 종료(열람 제한)
        In the present study, we investigated the role of binding immunoglobulin protein/glucose-regulated protein, 78-kDa (BIP/GRP78)-regulated endoplasmic reticulum (ER)-stress on meiotic maturation and cumulus cells expansion in porcine cumulus-oocyte complexes (COCs). Previously, it has been demonstrated that unfolded protein response (UPR)- related genes, such as molecules involved in ER-stress defense mechanisms, were expressed in matured oocytes and cumulus cells during in vitro maturation (IVM) of porcine oocytes. However, BIP/GRP78-mediated regulation of ER stress in porcine oocytes has not been reported. Firstly, we observed the effects of knockdown of BIP/GRP78 (an UPR initiation marker) using porcine-specific siRNAs (#909, #693, and #1570) on oocyte maturation. Among all siRNAs, siRNA #693 significantly reduced the protein levels of UPR marker proteins (BIP/GRP78, ATF4, and P90ATF6) in porcine COCs observed by Western blotting and immunofluorescence analysis. We also observed that the reduction of BIP/GRP78 levels by siRNA#693 significantly inhibited the meiotic maturation of oocytes (siRNA #693: 32.5±10.1% vs control: 77.8±5.3%). In addition, we also checked the effect of ER-stress inhibitors, tauroursodeoxycholic acid (TUDCA, 200 μM) and melatonin (0.1 μM), in BIP/ GRP78-knockdown oocytes. TUDCA and melatonin treatment could restore the expression levels of ER-stress marker proteins (BIP/GRP78, p-eIF2α, eIF2α, ATF4, and P90ATF6) in siRNA #693-transfected matured COCs. In conclusion, these results demonstrated that BIP/GRP78-mediated regulation of UPR signaling and ER stress plays an important role in in vitro maturation of porcine oocytes.
        2562.
        2017.12 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        The key risk analysis technologies for the re-entry of space objects into Earth’s atmosphere are divided into four categories: cataloguing and databases of the re-entry of space objects, lifetime and re-entry trajectory predictions, break-up models after re-entry and multiple debris distribution predictions, and ground impact probability models. In this study, we focused on reentry prediction, including orbital lifetime assessments, for space situational awareness systems. Re-entry predictions are very difficult and are affected by various sources of uncertainty. In particular, during uncontrolled re-entry, large spacecraft may break into several pieces of debris, and the surviving fragments can be a significant hazard for persons and properties on the ground. In recent years, specific methods and procedures have been developed to provide clear information for predicting and analyzing the re-entry of space objects and for ground-risk assessments. Representative tools include object reentry survival analysis tool (ORSAT) and debris assessment software (DAS) developed by National Aeronautics and Space Administration (NASA), spacecraft atmospheric re-entry and aerothermal break-up (SCARAB) and debris risk assessment and mitigation analysis (DRAMA) developed by European Space Agency (ESA), and semi-analytic tool for end of life analysis (STELA) developed by Centre National d’Etudes Spatiales (CNES). In this study, various surveys of existing re-entry space objects are reviewed, and an efficient re-entry prediction technique is suggested based on STELA, the life-cycle analysis tool for satellites, and DRAMA, a re-entry analysis tool. To verify the proposed method, the re-entry of the Tiangong-1 Space Lab, which is expected to re-enter Earth’s atmosphere shortly, was simulated. Eventually, these results will provide a basis for space situational awareness risk analyses of the re-entry of space objects.
        2563.
        2017.12 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        This study presents the application of satellite laser ranging (SLR) to orbit determination (OD) of high-Earth-orbit (HEO) satellites. Two HEO satellites are considered: the Quasi-Zenith Satellite-1 (QZS-1), a Japanese elliptical-inclinedgeosynchronous- orbit (EIGSO) satellite, and the Compass-G1, a Chinese geostationary-orbit (GEO) satellite. One week of normal point (NP) data were collected for each satellite to perform the OD based on the batch least-square process. Five SLR tracking stations successfully obtained 374 NPs for QZS-1 in eight days, whereas only two ground tracking stations could track Compass-G1, yielding 68 NPs in ten days. Two types of station bias estimation and a station data weighting strategy were utilized for the OD of QZS-1. The post-fit root-mean-square (RMS) residuals of the two week-long arcs were 11.98 cm and 10.77 cm when estimating the biases once in an arc (MBIAS). These residuals were decreased significantly to 2.40 cm and 3.60 cm by estimating the biases every pass (PBIAS). Then, the resultant OD precision was evaluated by the orbit overlap method, yielding three-dimensional errors of 55.013 m with MBIAS and 1.962 m with PBIAS for the overlap period of six days. For the OD of Compass-G1, no station weighting strategy was applied, and only MBIAS was utilized due to the lack of NPs. The post-fit RMS residuals of OD were 8.81 cm and 12.00 cm with 49 NPs and 47 NPs, respectively, and the corresponding threedimensional orbit overlap error for four days was 160.564 m. These results indicate that the amount of SLR tracking data is critical for obtaining precise OD of HEO satellites using SLR because additional parameters, such as station bias, are available for estimation with sufficient tracking data. Furthermore, the stand-alone SLR-based orbit solution is consistently attainable for HEO satellites if a target satellite is continuously trackable for a specific period.
        2564.
        2017.11 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        양파의 관행 수확과 저장 방식을 개선하여 벌크 상태로 수확하여 수송, 하역, 보관 및 저장할 수 있도록 톤백 및 와이어철제파렛트를 개발한 후 관행저장 방식과 벌크저장 후 저장성을 비교하고 그에 따른 노동투입시간 및 소요비용을 비교하여 양파의 산지물류비 절감 효과를 비교 분석하고자 하였다. 본 연구를 통해 개발된 톤백이 관행 톤백보다 길이방향 인장강도가 16% 높았으며, 개발한 와이어철제파렛트가 관행철제파렛트보다 약 10% 더 저장가능하고 차량 적재 효율도 2배 이상 향상되었다. 개발된 500 kg용 와이어 철제파렛트의 벌크저장과 관행 그물망 저장의 감모율에는 차이가 없었으나, 1,000 kg 이상 많은 양을 저장할 경우 와이어철제파렛트 벌크저장은 관행저장보다 감모율이 3.7% 높아 적합하지 않는 것으로 나타났다. 톤백을 이용한 벌크 수확이 관행 망 수확보다 노동시간이 50.1% 그리고 총 투입비용은 46.1% 감소할 수 있는 것으로 나타났다. 와이어철제파렛트를 적용한 벌크저장이 관행저장보다 총 저장비용이 28.8% 감소하였으며, 2016년 양파생산량 (1,298,749톤)의 30%를 와이어철제파렛트 벌크저장으로 대체할 경우 연간 183억 원을 절감할 것으로 추정된다. 따라서 현재 산지업체들의 와이어철제파렛트를 조기 도입하여 정착시키면 전국적으로 노동력 및 비용 절감에 상당한 효과가 있을 것으로 판단된다.
        2565.
        2017.10 KCI 등재 서비스 종료(열람 제한)
        본 연구에서는 장기예보자료 기반의 장기 가뭄전망정보를 산정하고, 2015년 가뭄사상을 대상으로 활용성을 평가하였다. 이를 위해 ASOS 59개 지점의 관측강수량, GloSea5의 미래예측 및 과거재현 자료를 활용하였으며, 다양한 지속기간(3, 6, 9, 12개월)에 대한 SPI를 산정하였다. 또한 예보선행시간(1~6개월)에 따른 SPI와 관측자료 기반의 SPI 간의 ROC (Receiver Operating Characteristic)및 통계적 분석(상관계수, 평균제곱근 오차)을 수행하여 전망정보의 활용성을 평가하였다. ROC 분석결과, SPI(3)는 2개월, SPI(6)은 3개월, SPI(9)는 4개월, SPI(12)는 5개월까지 ROC score 약 0.70 이상으로 산정되었다. 예보선행시간별 상관계수 및 평균제곱근오차의 경우, 2개월 선행시간 SPI(3)은 0.60, 0.87, 4개월 선행시간 SPI(6)은 0.72, 0.95, 5개월 선행시간 SPI(9)는 0.75, 0.95, 6개월 선행시간 SPI(12)는 0.77, 0.89로 상관계수는 높게, 평균제곱근오차는 낮게 산정되어 활용성이 있는 것으로 판단된다.
        2566.
        2017.10 KCI 등재 서비스 종료(열람 제한)
        Purpose – The purpose of this study is to present a framework for determining the most appropriate business model for e-learning. Research design, data, and methodology – The Electronics Branch of Azad University has been elected as a case study in this research. This study conducted using a descriptive method. The information was obtained using interviews with experts including managers, faculty and students at the Electronics Branch of Azad University. Results – Three service-product system (product oriented system, use an oriented and result oriented system) approaches determined a framework for the formation of a portfolio. This portfolio is including three types of e-learning business models. Examining the relevant characteristics, correspondence of behaviorism learning theory with a product-oriented approach, correspondence of cognitivism theory with a user-oriented approach and in finally match correspondence of constructivist learning theory with a results-oriented approach which is evident. Conclusions – After reviewing the literature on the fields of e-learning, business model and product - service systems, we have achieved three types of e-learning business models. Then the variables in any of the business models were defined by using business model canvas tool and thus a portfolio consisting of three types of e-learning business model canvas was obtained.
        2567.
        2017.10 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        Many workers today encounter the problem of overemployment which occurs when actual working hours exceed preferred or desired working hours. Overemployed workers desire to work fewer hours although this may entail a concomitant decline in earnings. This research is conducted to examine the likelihood of overemployment among employees in a particular state in Malaysia, that is, Penang. This study uses primary data that was collected in a survey encompassing a total of 525 employees in the state. A logit model is used to analyse the relationship between the likelihood of overemployment and various socio-demographic, household and work-related variables. The factors that are significantly related to overemployment are ethnicity, age, education, number of children in the household, occupation, hours of work and control over work schedule. Based on the findings of this paper, it is suggested that policies such as offering part-time jobs or jobsharing options to older workers, implementing family-friendly policies, adopting decent working time measures and strategies that give workers more control over their work schedule are some possible ways to deal with the issue of overemployment.
        2568.
        2017.10 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        The Northern States of Malaysia comprises of four states (Penang, Kedah, Perlis and Perak) still record high poverty incidence eventhough Malaysia has experienced a remarkable reduction of poverty over the past century. Economic activities in Perlis and Kedah that are predominantly agriculture in the rural area contribute to this disparity. To add, rural households are also subject to risks and uncertainties that make them more vulnerable to poverty. This study examines the impact of risks and assets on households’ vulnerability to poverty. A survey of 400 respondents was conducted in December 2015 in the northern region of Malaysia. From these 400 questionnaires, only 298 were considered valid and used in the analysis. Using a logistic probability function, the results indicated that risks are not a significant threat to households. Gender and strata are crucial elements that significantly determine households’ vulnerability. While human capital and financial capital significantly reduce households’ vulnerability to poverty, physical and natural capitals were not statistically significant. The study suggests that the government and practitioners design strategies and policies with an assets-based approach. The asset-based approach is more appropriate for linking the causes of poverty to vulnerability.
        2569.
        2017.09 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        A high resolution spectroscopic observation of the red supergiant star RM_1-390 in the Large Magellanic Cloud was made from a 3.6 m telescope at the European Southern Observatory. Spectral resolving power was R=20,000, with a signal-to-noise ratio S/N > 100. We found the atmospheric parameters of RM_1-390 to be as follows: the effective temperature Teff = 4,250 ± 50 K, the surface gravity log g = 0.16 ± 0.1, the microturbulent velocity vmicro = 2.5 km/s, the macroturbulence velocity vmacro = 9 km/s and the iron abundance [Fe/H] = -0.73 ± 0.11. The abundances of 18 chemical elements from silicon to thorium in the atmosphere of RM_1-390 were found using the spectrum synthesis method. The relative deficiencies of all elements are close to that of iron. The fit of abundance pattern by the solar system distribution of r- and s-element isotopes shows the importance of the s-process. The plot of relative abundances as a function of second ionization potentials of corresponding chemical elements allows us to find a possibility of convective energy transport in the photosphere of RM_1-390.
        2570.
        2017.09 KCI 등재 서비스 종료(열람 제한)
        The end of the Korean War did not bring about the end of Korea’s division. The theme of division runs through many South Korean literary works of the twentieth century. This so-called “division literature” can be characterized by its focus on the psychological pain of separation, and the (im)possibility of unification. The personal tragedies of separated families, of dashed hopes and dreams due to history’s vicissitudes, all these aspects appear in Korea’s modern literature and have their root in the Korean War. South Korean author Yi Munyŏl has been personally affected by the Korean War, and his trauma can be found in many of his writings. In “An Appointment with His Brother” (Auwa-ŭi mannam), published in 1995, he tries to find a means through literature to reach common ground with the other side (North Korea) for a possible future unification. He chose the Chinese city of Yanji as the setting for his story, a place where the majority of its population are ethnic Koreans who from 1992 onwards, have had connections with both North and South Korea. The city and its inhabitants serve as a liminal space where Yi Munyŏl can explore possibilities for reconciliation and to give shape to an imagined Korean unification.
        2571.
        2017.08 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        Considerable research has been done on the issue of succession in family businesses. However the process of induction, of preparing the members of the next generation for joining the family business has not been examined in detail. This paper attempts to analyse the relevance of three critical factors – ‘quality of relations’, ‘willingness of the inductee’ and ‘the ability to manage tensions harmoniously’ - to the induction process and the progress of the business. It focuses on the Indian context, specifically in the Small and medium Enterprise (SME) area. Qualitative research has been carried out. The Case Study method is used and data has been gathered from two families (including two branches of one family), using frequent unstructured interviews, over a period of five years. It is concluded that positive impact on business, family and the inductee depends to a large extent on the quality of relations, willingness of the inductee and the ability of both the inductor and inductee to handle and manage the tensions. Thus the findings of the study extend current understanding about succession drivers to the specific context of eastern cultural and developing economy represented by the Indian family businesses in the small and medium enterprise sector.
        2572.
        2017.08 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        This paper explores the impact of corporate control, measured by ownership structure, on top-executives’ compensation in Japan. According to agency theory, the pay-performance link is expected to be affected by the firm’s ownership structure. Using a sample of 4,411 firm-year observations (401 firms for the 11-years period from 2001 to 2011) for Japanese non-financial firms publicly traded on the first section and second section of the Tokyo Stock Exchange (TSE), this study demonstrates that institutional ownership (both financial and corporate) is negatively related to the level of executives’ compensation. Such finding is in line with efficient monitoring hypothesis which claims that the presence of institutional shareholders provides direct monitoring over managers, limits managerial self-dealing and curves the increase in top-executives pay. On the other hand, the results also show that managerial ownership is positively related to their compensation which supports managerial power theory hypothesis, i.e. management-controlled firms are more likely to extract more compensation from the business than other firms. Overall, this study confirms that corporate control has significant impact on cash compensation paid to Japanese top-executives after controlling the conventional pay-performance relationship.
        2573.
        2017.08 KCI 등재 서비스 종료(열람 제한)
        Purpose - While sustainability is based on the argument that the world’s resources are finite and their demand will ultimately surpass supply, entrepreneurship on the other hand argues that there are inherent opportunities to address this through conserving, recycling, switching to more renewable resources and making effective use of available finite resources. Research design, data, and methodology - In response to the lack of scientific information on the outcomes of entrepreneurship in rural Nigeria, this paper surveys the benefits (social, economic and environmental) of women engagement in waste plastic bags recycling in Adamawa State of Nigeria. A descriptive research design was adopted and data was collected from 26 respondents with the use of a semi-structured questionnaire, which was analyzed using descriptive statistics and presented in frequency tables. Results - Results indicated that 21 women have gained employment, who would have remained unemployed; 80.8% of who make profits below 10000 Naira per month and collectively, they recycle 179.3kg of waste polythene bag per month. Conclusions - It was recommended that the women should be further their education; adequate records of costs and sales should be kept; and savings should be encouraged among them.
        2574.
        2017.06 KCI 등재 서비스 종료(열람 제한)
        Barbaloin is a major component of Aloe vera, which has been used for a laxative. Also, barbaloin is C-glucoside of aloe emodin anthrone which is founded in Aloe vera. Barbaloin has varieties of pharmacological activity such as inhibitory effects on inflammation, histamine release, cancer and microbial infection. But the effect of barbaloin on lipopolysaccharide (LPS)-stimulated macrophages has not been understood. In this study, we evaluated the effects of barbaloin against LPS-stimulated production of nitric oxide (NO), inflammatory cytokines and MAPKs activation in macrophage. We treated barbaloin (0.1 , 1 , 10 , 100 μM) in LPS-stimulated mice peritoneal macrophage. Our results showed that barbaloin significantly inhibited production of NO and cytokines of tumor necrosis factor (TNF)-α, interleukin (IL)-6, interleukin (IL)-1β in LPS-stimulated peritoneal macrophage. Moreover, barbaloin inhibited the phosphorylation of ERK and JNK in a dose dependent manner. These results indicated that barbaloin could be useful for inflammatory diseases.
        2575.
        2017.06 KCI 등재 서비스 종료(열람 제한)
        This study analyzed the placement shape and correlation of green space focusing on anion that is one of curing substances. As its result, it was found out that the meteorological element becomes different and the generated amount of anion also gets different along such different meteorological element in case the shape of placing green space. As the result of analyzing the correlation with meteorological element , it was analyzed that it was the positive correlation in case of time, temperature and relative humidity and it was also analyzed that it was negative correlation in case of wind velocity and amount of light. But, in case of wind velocity, it was considered that the further complement research is required as the sampling distribution was shown as so biased by the windproof effect of the trees planted at the outskirts of green space in case of wind velocity. Based on th analyzed results as above, it suggested the model of generating anion by implementing multiple regression analysis such as y = -2462.383 + 0.304x1 x 72.746x2 x 7.315x3 x - 0.138x4 (x1; time, x2; air temperature, x3; relative humidity, x4; luminous intensity, R2; 0.691).
        2576.
        2017.06 KCI 등재 서비스 종료(열람 제한)
        Metformin is the most commonly prescribed anti-diabetic drug with relatively minor side effect. Substantial evidence has suggested that metformin is associated with decreased cancer risk and anticancer activity against diverse cancer cells. The tyrosine kinase inhibitor imatinib has shown powerful activity for treatment of chronic myeloid leukemia and also induces growth arrest and apoptosis in colorectal cancer cells. In this study, we tested the combination of imatinib and metformin against HCT15 colorectal cancer cells for effects on cell viability, cell cycle and autophagy. Our data show that metformin synergistically enhances the imatinib cytotoxicity in HCT15 cells as indicated by combination and drug reduction indices. We also demonstrate that the combination causes synergistic down-regulation of pERK, cell cycle arrest in S and G2/M phases via reduction of cyclin B1 level. Moreover, the combination resulted in autophagy induction as revealed by increased acidic vesicular organelles and cleaved form of LC3-II. Inhibition of autophagic process by chloroquine led to decreased cell viability, suggesting that induction of autophagy seems to play a cell protective role that may act against anticancer effects. In conclusion, our present data suggest that metformin in combination with imatinib might be a promising therapeutic option in colorectal cancer.
        2577.
        2017.06 KCI 등재 서비스 종료(열람 제한)
        At the Brain MRI examination, RF Pulse are irradiated on the human head in order to acquire MR images. At this time, a considerable part of the irradiated RF Pulse energy is absorbed in our body and the temperature of the human head will rise depending on the degree of exposure, so it will affect the human head. Even if the same RF Pulse energy is given, if the metal is inserted in the human head, the conductivity of the human head is greatly increased by the metal, so the SAR value increases and the temperature also rises. Therefore, we started this research with the question as to whether there is difference between the change in SAR value and temperature displayed on the head of the human according to use or not of the dental implant. Experiments were using the XFDTD program on a 128 MHz RF Pulse frequency by a 3.0 tesla MRI. We can see that both are increasing that the average value of SAR and temperature that absorbed by the human head model used the dental implant. In addition, the average maximum SAR value and the maximum temperature rise in the brain part are shown below the international safety standard value but the influence can not be ignored because of the result may change according to the increase in the number of dental implant. And as future tasks. we need to the simulation of temperature rise and SAR due to an increase in the number of implants and volumes of teeth, dental implant material.
        2578.
        2017.06 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        High-resolution spectroscopic observations of the eclipsing binary system RR Lyn were made using the 1.8 m telescope at the Bohuynsan Optical Astronomical Observatory in Korea. The spectral resolving power was R = 82,000, with a signal to noise ratio of S/N > 150. We found the effective temperatures and surface gravities of the primary and secondary components to be equal to Teff = 7,920 & 7,210 K and log(g) = 3.80 & 4.16, respectively. The abundances of 34 and 17 different chemical elements were found in the atmospheric components. Correlations between the derived abundances with condensation temperatures and the second ionization potentials of these elements are discussed. The primary component is a typical metallic line star with the abundances of light and iron group elements close to solar values, while elements with atomic numbers Z > 30 are overabundant by 0.5–1.5 dex with respect to solar values. The secondary component is a λ Boo type star. In this type of stars, CNO abundances are close to solar values, while the abundance pattern shows a negative correlation with condensation temperatures.
        2579.
        2017.06 서비스 종료(열람 제한)
        Urachal cancer is extremely rare and accounts for fewer than 1% of malignant neoplasms of the bladder. Urachal remnants persist from the bladder dome to umbilicus after birth, and urachal carcinoma may arise from any of these segments. The standard treatment for urachal cancer is primarily wide excision with extended partial cystectomy of the urachal mass, urachal tract and umbilicus, and pelvic lymph node dissection. Nevertheless, prognosis is generally poor because early diagnosis is difficult and local invasions, distant metastasis, and recurrence frequently develop. The authors present a patient with recurred urachal adenocarcinoma, who was treated by partial cystectomy with lymph node dissection. One year after subsequent concurrent chemoradiotherapy, she achieved complete remission. A brief review of the literature on urachal adenocarcinoma is provided.
        2580.
        2017.05 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        It is undisputable that crude oil and its price fluctuations are major components that affect most of the countries’ economies. Recent studies have demonstrated that beside the impact that crude oil price fluctuations have on common macroeconomic indicators like gross domestic product (GDP), inflation rates, exchange rates, unemployment rate, etc., it also has a strong influence on stock markets and their performance. This relationship has been examined in a number of settings, but it is yet to be unraveled in the Omani context. Accordingly, the main purpose of this study is to examine the possible effect of the oil price fluctuations on stock price movements. The study applies Toda and Yamamoto’s (1995) Granger non-causality test on the daily Oman stock index (Muscat Securities Market Index) and oil prices between the period of 2 January 2003 and 13 March 2016. The results indicated that the oil price fluctuations have a significant impact on stock index movements. However, the stock price movements do not have a significant impact on oil prices. These findings have significant implications not only for the Omani economy but also for the economy of similar countries, particularly in the Gulf Cooperation Council (GCC) countries. The latter should carefully consider their policies and strategies regarding crude oil production and the generated income allocation as it might potentially affect the financial markets performance in these countries.