• 한국작물학회지
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• 제49권1호
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• pp.52-60
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• 2004

The optimized in vitro culture system was investigated for improvement of regeneration efficiencies by observing the responses of scutella-derived callus of Korean rice (Oryza sativa L.). Large variations of callus induction (43.9-93.9%) and shoot regeneration (0-88.7%) were observed among the rice cultivars depending on medium. However, shoot regeneration was significantly improved by selected utilization of basal medium, growth regulators, and carbon sources. N6 basal medium was more efficient for embryogenic callus induction than MS or LS basal medium, while MS was superior to N6 for shoot regeneration. The calli of highly regenerative cultivars grew faster and showed higher rates of green tissue formation (GT) and shoot regeneration (SR) and lower rate of callus browning (CB) than those of recalcitrant cultivars. Although a higher level of kinetin stimulated the GT and SR in highly regenerative cultivars, $10\textrm{mgL}^{-1}$ kinetin generally suppressed the GT and SR, while CB was accelerated compared to $2\textrm{mgL}^{-1}$ kinetin. Additional benefits of sorbitol combined with maltose (or sucrose) under $5\textrm{mgL}^{-1}$ kinetin were certainly confirmed on regeneration efficiencies compared to sucrose alone as carbon source and osmotic regulator. This combination showed high rate of GT and SR with multiple shoots while low rate of CB. With MSRK5SM-Pr medium ($5\textrm{mgL}^{-1}$ kinetin, 3% sorbitol, 2% maltose, $500\textrm{mgL}^{-1}$ proline), the regeneration efficiencies of total 17 out of 24 cultivars were practically improved 160% on average compared to MSRK2S ($2\textrm{mgL}^{-1}$ kinetin, 3% sucrose) control medium. Especially, the medium was most effective to the cultivars showing a medium level of regenerability such as Daesanbyeo and Dongjinbyeo and Suwon477, enhancing efficiencies more than 300-600% compared to MSRK2S medium.

• 식물조직배양학회지
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• 제25권4호
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• pp.231-236
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• 1998

배지상에 여과지를 덮어놓는 간단한 물리적 처리가 체세포배의 발생 및 발아에 미치는 영향을 밝히기 위하여 본 실험관찰을 수행하였다. 배지상에 덮어놓은 세장의 여과지위에서 일주일 동안 당근 자엽절편을 배양한 후 MS 기본배지에 계대배양을 하면 여과지 덮개 없는 배지에서의 체세포배발생 보다 2배에서 39배의 배발생을 나타내었고, 체세포배의 성숙 및 발아도 증진되었다. 배지상의 여과지에 배양액을 첨가한 다음 배양을 하면 여과지에 배양액을 첨가하지 않은 경우보다 배발생이 감소되었다. 그러므로 여과지덮개는 자엽절편을 치상한 배양환경의 습기를 변화시켜 체세포배의 발생을 증진시킨 것으로 생각된다.

• 기술혁신연구
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• 제8권1호
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• pp.49-71
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• 2000

This paper looks at "network" aspects of research and development (R'||'&'||'D) with a special focus on small and medium (S'||'&'||'M) automotive part makers in Korea. It throws light on recent changes in the technological capability building mechanism of Korean automotive firms. The Korean automotive firms have mostly built up technological capability from scratch. It is widely acknowledged that they have benefited from two cooperative relations: namely (1) the close cooperative relationship with their own assemblers and (2) technical assistance from auto parts makers abroad. Too much emphasis on these two links can, however, keep us from understanding new developments. This paper argues that auto parts firms have diversified their networks for technological development. It is based on the analysis of the data drawn from the survey on technological development activities of small and medium sized firms, which was carried out by the Korea Federation of Small and Medium Business. Many automotive firms have recently increased joint R'||'&'||'D links with university and/or research institution while their reliance on foreign sources have decreased.

• 대한산업공학회지
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• 제41권2호
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• pp.162-172
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• 2015

This paper proposes a Product Data Management (PDM) system architecture that supports end-user computing for small and medium businesses (SMBs) in Korea to build and maintain efficient and sustainable information systems for their product development. Its open database with relational tables enables existing common application programs such as Microsoft office suites to access product data in PDM systems. In addition, the interactive query processor provided by database management systems helps design engineers to build ad hoc queries in standard SQL database language to response different data requirements during their product development. The PDM architecture with the open database allows design engineers or technical staffs in SMBs to build and maintain their application programs for product development by themselves. To show the feasibility of the proposed architecture, this study implemented a prototype PDM system based on the architecture and database, and represents real-world product data with the implemented PDM system.

• Asia pacific journal of information systems
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• 제5권1호
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• pp.186-218
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• 1995

The necessity of installing well adaptable Information Systems are required day by day in all the fields of business management. This paper provides an Information System development for enhancing competitive power of the small and medium-sized firms in Korea. Recent growing Information Technology leads to constructing invisibly some new adaptable Information Systems in accordance with the business size, level, capacity and requirements. Even though some advanced companies and big enterprises are already operating their own appropriate Information Systems so as to get their remarkable productivity at a moment. The rest of those small firms are still trying to find out some proper systems fitting their own business in very poor situations. The basic requirements of the points of views by mail questionaired and interviewed from 1292 small and medium-sized manufacturing firms reflected on this Information System development. As a result, the study introduces some economically efficient, convinient, flexible and useful applied Information Systems with simple methods.

• 산업경영시스템학회지
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• 제6권9호
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• pp.45-59
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• 1983

This study focuses on the growth and development of small and medium industries of Korea, orienting to the development of up-to-date technology from now on and bolstering their competitive ability in the rapidly changing international markets. For this purpose, the small and medium industries should 1) develop high-level manpower of up-to-date technology, 2) make constant efforts to categorize and divide the fields of technology with big business groups to boost their competitiveness, 3) raise automation rate by turning all facilities into mechatronics, 4) positively develop software know-how, 5) jointly conduct researches in cooperation with venture capital and Governmental research institute, 6) categorize an systematize the industries. On the Governmental level, there should be 1) wide-ranging support and assistance in technology, finance, and the facilities, 2) positive opening of consumer market, 3) assistance in technical cooperation with other nations, 4) and such indirect assistance as fostering the fields of related technology.

• International Journal of Railway
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• 제8권1호
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• pp.21-29
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• 2015

This study focuses on the performance enhancement of the levitation and guidance control system in urban and medium-to high-speed magnetic levitation trains. A levitation control system, which is currently being tested in Yeongjongdo, is a single controller that is neither designed nor produced on the basis of redundancy. Hence, vehicular stability and reliability should be improved for the situation in which levitation failure occurs because of a breakdown in a controller during vehicle operation. In addition, the control system should be developed to control electromagnetic levitation considering changes in normal force according to changes in the driving force of the propulsion system.

• 한국수정란이식학회지
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• 제24권3호
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• pp.145-150
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• 2009

This study was conducted to examine the effects of human follicular fluid and gonadotropin (FSH+HCG+rhEGF) on in vitro maturation, fertilization and development of human immature oocytes. Cumulus-oocyte complexes (COCs) were collected following for in vitro fertilization and embryo transfer (IVF-ET) cycles of the patients. At the time of oocytes collection, oocytes were classified into MII, MI and GV in accordance with their appearance (MII: Fully mature oocyte at metaphase II of meiosis; MI: Nearly mature oocytes at metaphase I of meiosis; GV: Immature oocytes at prophase I of meiosis). After controlled ovarian stimulation using gonadotropin(FSH) and human chorionic gonadotropin (HCG) in 70 ICSI cycles, 158 MI to MII matured oocytes were intracytoplasmic sperm injection (ICSI) ${\sim}4$ h after in vitro culture and 553 MII oocytes were ICSI after denudation. The aspirated MI and GV oocytes were cultured in culture medium containing 10% (v/v) serum protein substitute (SPS), 10% (v/v) human follicular fluid (hFF) and 10% (v/v) serum protein substitute (SPS)+1 IU/ml FSH+10 IU/ml HCG+10 ng/ml recombinant human epidermal growth factor (rhEGF). The maturation rate of immature oocytes was similar among the three group. When maturation medium was supplemented with 10% SPS, 10% hFF or gonadotropins, the fertilization rate of in vitro matured oocytes was higher in 10% SPS (80.0%), but there was no statistical significance (78.2%; hFF, 76.9%; gonadotropin, p>0.05). The development rate of human embryos developed to $6{\sim}8$ cells were not significant difference in the medium containing SPS, hFF and gonadotropins (65.6%, 65.9% and 66.7%). The results of these study suggest that human follicular fluid and gonadotropins supplemented in the culture medium was not effected on the in vitro maturation, fertilization and development of human immature oocytes.

• Reproductive and Developmental Biology
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• 제29권3호
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• pp.145-147
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• 2005

Autocrine or paracrine mediators released by the early embryo are implicated in the support of embryonic development. Their mechanisms and optimal embryo density in the medium, however, are uncertain. This study was conducted to establish the optimal embryo density and culture medium volume in mouse parthenogenetic embryo culture. In experiment 1, culture of parthenogenetirally activated oocytes at a concentration of $2{\~}4$ embryos/${\mu}L$ significantly improved development to the blastoryst stage ($72{\%}{\leq}$) compared with culture at the lower ($0.2{\~}1$e mbryos/${\mu}L,\;0\~37.5\%$) and the higher ($5{\~}6$ embryos/${\mu}L,\;30\~53\%$) concentration for 120 h when the oocytes were cultured in a 5 ${\mu}L$ drop under mineral oil In experiment 2, the embryos cultured at a concentration of $2{\~}4$ embryos/${\mu}L$ in a 10 ${\mu}L$ drop ($81.1{\%}$) showed significantly higher blastocyst rates than those in a 5 ${\mu}L$ drop ($68.5{\%}$). This study optimizes in vitro culture condition by modifying embryo density and the volume of culture medium It may give appropriate level of autocrine and/or paracrine factors to enhance viability and subsequent normal development of mouse parthenogenetic embryos in vitro.

• 한국수정란이식학회지
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• 제28권1호
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• pp.41-48
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• 2013

This study examined the motility of either the unattached(upper) or attached(lower) Hanwoo sperm to bovine oviduct epithelial cell(BOEC) monolayers to determine whether there are any changes in their motility during co-culture. The cleavage and blastocyst development rate were compared among different preincubation methods in-vitro, after oocytes were fertilized in-vitro with Hanwoo sperm on BOEC monolayers. The motility of frozen-thawed sperm in BOEC co-culture group was significantly higher than controls, especially at 5 hours and 6 hours (p<0.05) of incubation, in sperm treatment medium without heparin and caffeine. The motility of frozen-thawed sperm in BOEC co-culture group was significantly higher than controls, especially at 3 hours (p<0.05) and 6 hours (p<0.01), in sperm treatment medium containing heparin and caffeine. The motility of the attached( lower) sperm was significantly higher than the unattached(upper) sperm during co-culture with BOEC at all times(p<0.01 or p<0.05), except for 6 hours. After Hanwoo oocytes were fertilized in-vitro with the sperm that had been co-cultured with BOEC in sperm treatment medium containing heparin and caffeine, we determined the cleavage and blastocyst development rate, according to the preincubation methods. Both the cleavage and blastocyst development rate from 2 hour preincubation group were the highest, but significant difference was not recognized. These results show that BOEC plays an important role on sperm hyperactivation related to capacitation regardless of heparin and caffeine in sperm treatment medium. However, oviduct epithelial cell had no significant effect on the development of embryos after in-vitro fertilization in the presence of added heparin and caffeine in sperm treatment medium.