• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1995.04a
• /
• pp.258-263
• /
• 1995

미래 정보와 시대에서 중추적인 역할을 할 광관련 멀티미디어 장비들은 최근 관련 산업계에서 주목을 받기 시작하고 있고 특히 기존 VTR(Video Tape Recorder) 시장을 대체할 차세대 DVDR(Digital Video Disk Recorder)는 기술전쟁이라고 할 정도로 선진 기업의 연구가 치열해지고 있다. DVDR 시스템에서는 필요한 정보들을 레이저빔을 이용한 광학신호로 바꾸어 광디스크에 기록, 재생하는 광픽업이 절대적으로 필요하게 된다. 그런데 광픽업의 위치추종기구인 Actuator는 정확한 위치추종(.+-.1.$\mu$m 오차이내)을 할 수 있는 성능이 요구되며 서보의 특성상 20KHz 이하에서 불필요한 모우드가 가진되지 않는 정밀부품이어야 하므로 Actuator 각 부품의 동적인 특성을 명확히 규명할 필요가 있다. 따라서 본 연구에서는 우선 Actuator 각 부품과 가동부 전체의 중량 및 진동해석을 통해 동특성을 조사하였다. 그리고 Actuator의 중요한 기본성능중 하나인 구동감도 확보여부를 검토할 필요가 있기 때문에 유한요소법 프로그램인 ANSYS를 이용하여 자기회로 부분에 대한 해석을 구하였다. 또한 가동부와 자기회로 등 하위부품을 조립하는 과정에서 발생하는 조립오차로 인해 불필요한 공진과 회전형상이 야기될 수 있으므로 동특성 및 문제점 파악을 위한 민감도 분석이 필요하다. 따라서 본 연구에서는 가동부의 관성 모멘트 값과 강체에 대한 일반식을 이용한 자체 프로그램을 작성하여 조립공차를 구하였다. 이와같은 과정을 통해 구해진 설계값을 바탕으로 실제 제작된 Actuator에 대해서는 비접촉식 측정방법을 통해 동특성값을 측정하였고 이를 해석값과 상호 비교하였다.동강성행렬법(dynamic stiffness matrix method)을 이용하여 해석하고자 한다. 수준임이 입증되었다. 본 연구의 결과를 토대로우리나라 젊고 건강한 남성에게 적합한 무게상수는 작업자군에 대하여 25.05kg, 학생군에 대하여 20.24kg 으로 나타나 이는 미국 NIOSH 안전기준과 대체로 일치함을 발견하였다.ive structures utilized in Client/server architecture for distribution and cooperative processing of application between server and client this study presents two different data management methods under the Client/server environment; one is "Remote Data Management Method" which uses file server or database server and. the other is "Distributed Data Management Method" using distributed database management system. The result of this study leads to the conclusion that in the client/server environment although distributed application is assumed, the data could become centralized (in the case of file server or database server) or decentralized (in the case of distributed

• Korean Journal of Remote Sensing
• /
• v.36 no.2_2
• /
• pp.293-307
• /
• 2020

Every year, the floating macroalgae, green and golden tide, are massively detected at the Yellow Sea and East China Sea. After influx of them to the aquaculture facility or beach, it occurs enormous economic losses to remove them. Currently, remote sensing is used effectively to detect the floating macroalgae flowed into the coast. But it has difficulties to detect the floating macroalgae exactly because of the wavelength overlapped with other targets in the ocean. Also, it is difficult to distinguish between green and golden tide because they have similar spectral characteristics. Therefore, we tried to distinguish between green and golden tide applying the Deep learning method to the satellite images. To determine the network, the optimal training conditions were searched to train the AlexNet. Also, Gaofen-1 WFV images were used as a dataset to train and validate the network. Under these conditions, the network was determined after training, and used to confirm the test data. As a result, the accuracy of test data is 88.89%, and it can be possible to distinguish between green and golden tide with precision of 66.67% and 100%, respectively. It is interpreted that the AlexNet can be pick up on the subtle differences between green and golden tide. Through this study, it is expected that the green and golden tide can be effectively classified from various objects in the ocean and distinguished each other.

• Korean Journal of Materials Research
• /
• v.8 no.3
• /
• pp.268-273
• /
• 1998

Standard Zircaloy-4 sheets, charged with 230-250ppm hydrogen by the gas-charging method and homogenized at $400^{\circ}C$ for 72hrs in a vacuum, were corroded in pure water and aqueous LiOH solutions using static autoclaves at $350^{\circ}C$. Their corrosion behaviors were characterized by measuring their weight gains with the corrosion time and observing their microstructures using an optical microscope and a scanning electron microscope. The elemental depth profiles for hydrogen and lithium were measured using a secondary ion mass spectrometry(S1MS) to confirm their distributions at the oxidelmetal interface. The normal Zircaloy-4 specimens corroded abruptly and heavily at the concentration of Li ions more than 30ppm in the aqueous solution. This is due to accelerations by the rapid oxidation of many Zr- hydrides formed by the large amount of absorbed hydrogen, resulting from the increased substitution of $Li^{+}$ ions with $Zr^{4+}$-sites in the oxide as the Li ion concentration increased. The specimens that had been charged with amounts of hydrogen greater than its solubility corroded early with a more rapid acceleration than normal specimens, regardless of the corrosion solutions. At longer corrosion times. however, normal specimens showed a rather accelerated corrosion rate compared to the hydrogen-charged specimens. These slower corrosion rates of the hydrogen-charged specimens at the longer corrosion times would be due to the pre-existent Zr-hydride in the matrix, which causes the hydrogen pick- up into the specimen to be depressed, when the oxide with an appropriate thickness formed.

• Korean Journal of Animal Reproduction
• /
• v.24 no.1
• /
• pp.83-88
• /
• 2000

This study was conducted to determine the effect of repeated ultrasound-guided transvaginal retrieval of oocytes recovery, estrous cycle and ovarian adhesion in Korean native, Hanwoo heifers. Heifers were at unknown stages of the estrous cycle at the start of experiments in which all follicles $\geq$6mm in diameter were ablated. The results obtained in this study were as follows; Follicle developing number and oocytes collected number were no effected to repeated OPU to nine session, 4 e.a range oocytes collected to repeated OPU session. Oocytes were observated follicles were 8.7$\pm$4.2 e.a, collected oocytes were 4.1$\pm$3.4 e.a to two times collected per week and observated follicles was 10.2$\pm$6.1 e.a, collected oocytes were 4.3$\pm$2.9 e.a to one times collected per week, but no difference significantly(P＜0.05). Ovaries adhesive percentage to repeated OPU was eight ovaries adhisived(20%) of forty ovaries, three ovaries(7.5%) to 1~3 times oocytes collected, four ovaries(l0%) to 4~6 times, one ovaries(2.5%) to 7~9 times oocytes collected session. To repeated OPU effection, ovaries adhisive heifers were long estrous cycle(＞25 day) to 7 heads(87.5%) of 8 head, non-adhesive ovaries heifers were 5 heads(41.7%) were long estrous cycle to repeated OPU 12 heads. Although, now unknown about the dynamics of follicles wave and about functional changes to repeated OPU ovaries, more question about ovaries adhesive cause remain.

• Journal of Korean Public Health Nursing
• /
• v.16 no.1
• /
• pp.45-63
• /
• 2002

The purpose of this study is to understand the current status of high school students' exposure to pornographic materials as well as to provide basic data to develop sex education programs. This study was conducted through a self-administered questionnaire survey of 774 students of six high schools in Seoul, three boys' and three girls' respectively, from August 22 to August 25, 2000. This study shows that high school students' exposure to pornographic materials such as CD-ROMs, internet, video tapes and adult movies has become very serious. The results of this study are as follows. 1. Among the students surveyed, $23.5\%$ of them currently has opposite-sex friends, while $42.2\%$ used to have and $34.2\%$ has never had opposite-sex friends. 2. $55.3\%$ of the students pick up their sexual knowledge from their friends, followed by mass media $(47.5\%),\;school (21.1\%),\;adult\; magazines (17.1\%)\;, internet (14.1\%)$, pornography visual $materials (11.5\%),\; sexual\; books (3.6\%)$ and pornography printed $materials (2.4\%).$ 3. Regarding the frequency of sexual education taken in school, $54.2\%$ of the students answered 'often', while $37.6\%$ answered 'almost none', 'several times' $(4.4\%)$, 'never' $(2.9\%)$ and 'frequently' $(0.9\%)$, respectively. Regarding sexual education at home, $42.2\%$ answered 'almost none', followed by 'never' $(36.3\%)$, 'often' $(16.3\%)$, 'several times' $(3.3\%)$ and 'frequently' $(1.8\%)$, respectively. 4. $68.2\%$ of the students have been exposed to adult movies, followed by pornography videos $(60.1\%)$, internet chatting $(50.2\%)$ and pornography computer diskettes $(38.0\%)$. 5. The degree of exposure to pornographic materials of boy students is much higher than that of girl students. 6. It appears that there is an interrelation between the kind of schools and the degree of the students' exposure to pornographic materials. 7. The higher the students' grade is. the more they have been exposed to pornographic materials. 8. It shows that there is an interrelation between the students' academic performance and the degree of their exposure to pornographic materials. 9. There is also an interrelation between the amount of students' pocket money and the degree of their exposure to pornographic materials. 10. There is an interrelation between the degree of their adaptation to school life and the degree of their exposure to pornographic materials. 11. It appears that there is an interrelation between their parents' relations with them and the degree of the students' exposure to pornographic materials. 12. There is a significant difference in the degree of their exposure to pornographic materials in accordance with their residential area. 13. There is also a significant difference in the degree of their exposure to pornographic materials in accordance with the average income of their families. 14. There is also a significant difference in the degree of their exposure to pornographic materials in accordance with the mean sexual education at home.

• Journal of Radiation Protection and Research
• /
• v.28 no.1
• /
• pp.35-42
• /
• 2003

Methodology for calculating the organ equivalent doses and the effective doses of pediatric and adult patients undergoing medical X-ray examinations were established. The MIRD-type mathematical phantoms of 4 age groups were constructed with addition of the esophagus to the same phantoms. Two typical examination procedures, chest PA and abdomen AP, were simulated for the pediatric patients as well as the adult as illustrative examples. The results confirmed that patients pick up approximate 0.03 mSv of effective dose from a single chest PA examination, and 0.4 to 1.7 mSv from an abdomen AP examination depending on the ages. For dose calculations where irradiation is made with a limited field, the details of the position, size and shape of the organs and the organ depth from the entrance surface considerably affect the resulting doses. Therefore, it is important to optimize radiation protection by control of X-ray properties and beam examination field. The calculation result, provided in this study, can be used to implement optimization for medical radiation protection.

• Nuclear Engineering and Technology
• /
• v.21 no.2
• /
• pp.89-98
• /
• 1989

The expanding copper mandrel test performed at three strain rates (3.2$\times$10E -5/s, 2.0$\times$10E-6/s and 1.2$\times$10E-7/s) over 553-873 K temperature range by varying the heating rates (8-1$0^{\circ}C$/s, 1-2$^{\circ}C$/s and 0.5$^{\circ}C$/s) in air and in vacuum (5$\times$10E-5 torr). The yield stress peak, the strain rate sensitivity minimum and the activation volume peaks could be explained in terms of the dynamic strain aging. The activation energy for dynamic strain aging obtained from the yield stress peak temperature and strain rate was 196 KJ/mol and this value was in good agreement with the activation energy for oxygen diffusion in $\alpha$-zirconium and Zircaloy-2 (207-220 KJ/mol). Therefore, oxygen atoms are responsible for the dynamic strain aging which appeared between 573 K and 673 K. The yield stress increase due to the oxidation was obtained by comparing the yield stress in air with that in vacuum and represented by the percentage increase of yield stress ( $\sigma$$^{a}$ $_{y}$ - $\sigma$$^{v}$ $_{y}$ / $\sigma$$^{v}$ $_{y}$ ). The slower the strain rate, the greater the percentage increase occurs. In order to estimate the yield stress of PWR fuel cladding material under the service environment, the yield stress in water was obtained by comparing the oxidation rate in air that in water assuming the relationship between the oxygen pick-up amount and the yield stress increase.

• Proceedings of the KAIS Fall Conference
• /
• 2001.05a
• /
• pp.62-65
• /
• 2001

1997년과 1998년 4월 1일자의 M&A제한규정이었던 증권거래법 제200조의 철폐와 적대적 M&A의 전면허용 그리고 외국자본의 투자제한의 간소화 등 규제완화조치와, 향후 외국인에 대해서 100%까지 주식을 매입할 수 있는 적대적 M&A가 허용될 것으로 보여 우리나라에서도 M&A활동이 보다 본격화 될 것으로 전망되고 있다. 우리나라에서는 1980년대부터 M&A에 대한 관심과 연구가 시작되면서 지금까지 기업합병ㆍ인수의 동기와 효과에 대해서 많은 연구가 이루어져 왔다. 지금까지의 연구내용은 대부분 기업의 M&A동기는 시너지효과를 얻기 위함이며, 또한 공시정보가 합병공시일 전후동안에 주가수익율에 반영되어 합병 당사기업의 주주의 부에 영향을 미치는지의 주가변화 유무에 국한된 것이었다. 또한 1985년부터 1991년 초 사이에 이루어졌던 연구는 당시 국내 M&A 환경이 매우 열악하고 극히 제한된 비정상적인 자본시장 상황 하에서 이루어진 사례에 의한 연구이었기 때문에 연구결과의 문제점과 한계성이 있었고, 실효성 측면에서도 다소 미흡하였다고 할 수 있다. 우리나라 M&A의 성장발전과정을 크게 2단계로 분류한다면, 제1단계는 1975년부터 시작하여 1990년까지로써 이 기간동안의 M&A환경은 그 여건조성과 성숙준비단계였으며, 제2단계인 1990년 초부터 비로소 선진국형 시장경제원리에 근거한 보다 경쟁적이고 자율적인 M&A 시장구조가 형성되면서 활성화 단계로 진입하였다고 볼 수 있을 것이다. 본 연구의 주된 목적은 1990년부터 1996년 사이에 이루어진 상장기업의 M&A 사례를 표본으로 하여 한국에서의 기업합병과 기업인수(주식취득)가 기업가치에 미치는 영향을 구명하는데 있다. 이를 위하여 먼저, M&A 당사기업의 합병성과 발생과 차이 유무를 주가수익율을 측정하여 실증분석하고 다음으로 M&A에 따른 시너지의 잠재적 원천이 어디에 있는지 재무성과분석을 통해서 이를 실증하는데 목적이 있다.PA-designated retailers ("sellers") must accept end-of-life items returned to them by the consumers. At the local level, Taipei City implements a pay-as-you-throw program, whereby citizens pay waste collection and treatment fees through the purchase of special trash bags approved by the Taipei City Government. However. recyclables that are separated by citizens are collected free-of-charge by the City. Taichung City and Kaohsiung City, on the other hand, enforce mandatory sorting schemes, whereby citizens face penalties if they don't separate recyclables from the trash before pick-up. These programs have resulted in a significant reduction in municipal waste. Per capita waste collected per day has dropped from 1.143 kg in 1997 to 0.978 kg in 2000. Targeting a 10% recycling rate for municipal waste in 2001. EPA plans to research and develop new recycling techniques, expand the scope of producer responsibilities, and strengthen existing mu

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 1999.10a
• /
• pp.299-308
• /
• 1999

오늘날 우리 나라가 당면한 최우선 경제과제중 하나는 물류부분의 혁신을 통한 국가경쟁력 강화라고 할 수 있으며, 이를 위해 정부도 1993년 물류체계 개선을 위한 장기구상으로 ‘화물유통체계 개선 10개년 기본계획’을 수립하여 적극 추진 중에 있다. 그러나 이러한 노력에도 불구하고 PORT-MIS사용자를 상대로 한 설문조사에서는 선박입출항 업무 관련 서류의 40%, 항만시설 사용 업무와 관련된 서류의 31%, 하역업무 관련 서류의 10%만이 EDI를 활용하고 있었다. EDI 활용이 저조한 사유로는 전송시간이 많이 걸리며, EDI 소프트웨어가 작동되지 않으며, 수신확인이 되지 않기 때문이라 응답을 하였다. 이처럼 오늘날 항만물류산업이 겪고 있는 물류 데이터 흐름이 단절적 현상은 시간이 흐를수록 해결 될 기미가 보이고 있지 않다. 따라서 본 논문에서는 우리 나라가 겪고 있는 물류관련 업무를 한번의 데이터 입력으로 해결할 수 있는 원스톱 서비스 시스템개발을 목표로 우선 PORT-MIS EDI 업무를 처리할 수 있는 시스템을 구축하였다. 이는 향후 화주, 운송사, 선사, 포워더, 창고업자,하역회사, 철도청, 화물터미널, 컨테이너 터미널, 해양수산청, 관세청, 출입국관리사무소, 검역소 사이에 서로 교환되는 적하목록, Booking List, 컨테이너 Pick up정보, 위험물 정보, COPINO 정보를 비롯하여 대 관세청 신고 등 수출컨테이너 화물업무의 전반적인 영역으로까지 쉽게 확대할 수 있을 것이다. 본 연구결과 구축된 시스템은 원천정보를 중앙의 통합데이터베이스에 저장하여 이를 사용자의 요구에 의해 인터넷을 통해 전달하는 FTP와 웹 EDI 방식을 결합한 하이브리드 형태이다.CS Cell 방식에 의한 위치결정방식을 채택하였는데, 이것은 PCS망을 기반으로 데이터를 주고받이며 인터넷 단말기로 확장 가능한 PCS 단말기를 사용해서 위치추적을 하는 시스템이다. 이러한 시스템을 선정하게된 배경은 단말기아 망 이용료의 가격이 저렴하여 현실적으로 트럭이 쉽게 부착할 수 있다는 장점이 있으며 나아가 인터넷 단말기를 활용하여 차량과 관제센터사이에 메시지 전송 등 부가적인 서비스가 가능하기 때문이다.비교한 결과 토사 유출 억제효과는 한지형과 나지형잔디들의 혼합형(MixtureIII)과 자생처리구(MixtureV), Italian ryegrass와 자생식물의 혼합형(MixtureIV)등에서 비교적 낮은 수치를 토사유출량을 기록하였다. 이러한 결과는 자생식물들이 비록 초기생육속도는 외래도입초종에 떨어지지만 토사유출의 억제효과면에서는 이들 외래초종에 필적할 수 있음을 나타낸다고 할 수 있겠다.중량이 약 115kg/$m^2$정도로 나타났다.소 들(환경의 의미, 사람의 목적과 지식)보다 미학적 경험에 주는 영향이 큰 것으로 나타났으며, 모든 사람들에게 비슷한 미학적 경험을 발생시키는 것 이 밝혀졌다. 다시 말하면 모든 사람들은 그들의 문화적인 국적과 사회적 인 직업의 차이, 목적의 차이, 또한 환경의 의미의 차이에 상관없이 아름다 운 경관(High-beauty landscape)을 주거지나 나들이 장소로서 선호했으며, 아름답다고 평가했다. 반면에, 사람들이 갖고 있는 문화의 차이, 직업의 차 이, 목적의 차이, 그리고 환경의 의미의 차이에 따라 경관의 미학적 평가가 달라진 것으로 나타났다.corner$적 의도에 의한 경관구성의 일면을 확인

• Journal of Veterinary Clinics
• /
• v.32 no.4
• /
• pp.324-329
• /
• 2015

The primary aim of this study was to investigate biosecurity practices in pig farms and to determine the major risk factors associated with PCV2 infection for a sampled swine population in Korea. To this end, we analyzed data from a cross-sectional study of 296 farrow-to-finish farms, which was conducted between March and September 2014 to explore the prevalence of swine disease at farm level. Face-to-face interviews by on-site visit of trained veterinarians were conducted with the farm owners or managers using a standardized questionnaires with information about basic demographical data and management practices. Farms were classified as negative or positive through the use of infection profiles that combined data on serological testing including PCR antigen test result, antibody titer and sero-conversion pattern at each age category taking into account vaccination status. Data were analyzed using multivariate ordinal logistic regression. Results from this study indicated that biosecurity level of the farms was considered not good given low compliance of the biosecurity programs and facilities in the farm: off-site removal of dead stocks (7%), off-site location of storage facility for incoming feeds (12.6%), off-site pick-up location for finishers (19.3%), restrictions on feed supplier vehicles for farm entrance (19.6%), restriction of finisher trucks entering the farm (22.4%), and restriction on manure disposal trucks entering the farm (26.4%). In the final model (n = 255), allowance of finisher truck driver to the pig unit had increased risk of infection (OR = 2.4, 95% CI 1.22-4.67) whereas farms with a sign forbidding the entrance had decreased risk of infection (OR = 0.19, 95% CI 0.10-0.58). Further comprehensive research with larger sample size is required to better understand the multifactorial characteristic that some predisposing risk factors that were not available in this study. To the best knowledge of the authors, this was the first study to use empirical data to report risk factors associated with PCV2 infection in the Korean pig farms. Results from the current study could be used to decide optimal biosecurity measures to reduce the impact of PCV2 infection to farmers and policy makers.