• NEWSLETTER 전기공업
• /
• no.94-10 s.107
• /
• pp.28-56
• /
• 1994

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.2
• /
• pp.223-226
• /
• 2005

본 논문에서는 지능형 교통망 시스템 서비스에 사용하는 5.8GHz 대역에서 OFDM을 이용한 단거리 전용 통신 시스템의 성능을 분석하였다. 현재의 DSRC 시스템은 1Mbps 이상의 데이터 서비스가 어려울 것으로 예상되므로 개선도니 변복조방식이 요구된다. OFDM(orthogonal frequency division multiplexing) 방식은 보호구간의 삽입을 통하여 ISI를 방지할 수 있으므로 고속 데이터 전송에 적합하다. 따라서, 본 논문에서는 데이터 변조 방식으로는 IEEE 802.11a에 근거한 부 반송파의 수가 64개인 QPSK변조 방식을 사용하는 OFDM 시스템을 모델링 하고, 도플러 천이 효과를 고려한 Clark & Gans 페이딩 환경에서 성능을 분석하였다. 또한 페이딩 환경에서는 성능의 열화 정도가 크기 때문에 이를 극복하기 위해 채널 예측기를 사용하여 채널 응답을 근사적으로 예측${\cdot}$보상하였다.

• (The)Study of the Eastern Classic
• /
• no.73
• /
• pp.185-217
• /
• 2018

This research is a part of basic research on Gyeonggi Kamyoung focused on reconstruct personnel organization and facility of Gyeonggi Kamyoung, the only Kamyoung without a Kamyoung Record, which should have been recorded on it. Excluding Gyeonggi Kamyoung, other 7 Kamyoung each have its Kamyoung Record that shows their detailed history and set up. Due to lack of information about Gyeonggi Kamyoung, this research set objective on reconstructing Kamyoung Record of it with fragments of information on multiple historical records. By doing this, this research will also be a background for general research on distinguishing administrative unity from regional uniqueness of all 8 provinces Kamyoung. Kamyoung's personnel organization is sorted into government official from central government and Yeongli and staff. The information about the government official on this research is based on "Ki-Yung-Jang-Gae- Deung-Rok"'s personal assessment. According to it, Dosa Junggun Geomlyul had the same task and position as others in different provinces did. The difference Gyeonggi Kamyoung had was an absence of Sim Yak since 1700 while others still had it. The information about Yeongli and staff's organization was based on "Ki-Yeong-Sin-Jeong-Sa-Le". In Gyeonggi Kamyoung, along 6-Bang, there were 208 Yeongli and staff categorized into 50 different official duties. Also, compared to other Kamyoungs, Youngli's scale was smaller. Kamyoung's facility inside Pojeongmun and wall is distinguished from other Kamyoung related facilities in this research. Organization of facilities inside Pojeongmun and wall is based on "Gyeonggi-Kamyoung-Do". Like other Kamyoungs in different provinces, Seonhwadang, which is the main building, is located in the center and had a similar organization. Significant point was that Gyeonggi Kamyoung had both Youngli-Cheong and Hyeongli-Cheong at the same time. In the dense and developed area outside of Seodaemun, Gyeonggi Kamyoung had its related facility around it in small scale.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.6 no.3
• /
• pp.36-54
• /
• 1995

The error performance of digital radio signals (i.e., M-ary PSK signal, DQPSK signal, MSK signal, GMSK signal) interfered by impulsive noise and electromagnetic interference (EMI) is analyzed and discussed. In analysis at first, the error rate equations have been derived in an electromagnetic interference plus impulsive noise environment. And then, the error performance has been evaluated and shown in figures as a function of carrier-to-noise ratio, carrier-to-interference ratio, impu- lsive index, gaussian noise to impulsive noise power ratio, and interference index to measure the amount of error degradation in digital radio signals. From the obtained results we have known that in the presence of m-distributed tone interference plus inpulsive noise, the more significant the electromagnetic interference amplitude varies, the more significant performance degradation is produced. The listing the digital radio signals from the most degraded to the least is that DQPSK, GMSK, QPSK and MSK signal. In the constant amplitude tone interference plus impulsive noise environment, the effect of in- terference nearly disappears over about 20dB in CIR. The effect of constant tone interference on error rate performance is reduced more remarkably in the region from 10dB to 15dB in CIR. In both enviroments of m-distributed tone interference and constant amplitude tone interference, the more electromagnetic interference amplitude varies and CIR increases, the more error perfor- mance is improved. But it is found out that the performance can not be improved significantly even the electromagnetic interference becomes weak. This describes that the impulsive noise affects dominantly to the performance degradation.

• 한국태양에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.154-157
• /
• 2011

Hydrogenated silicon nitride deposited by LF-PECVD is commonly used for anti-reflection coating and passivation in silicon solar cell fabrication. The deposition of the optimized silicon nitride on the surface is elemental in crystalline silicon solar cell. In this work, the carrier lifetimes were measured while the thicknesses of $SiN_x$ were changed from 700 ${\AA}$ to 1150 ${\AA}$ with the gas flow of $SiH_4$ as 40 sccm and $NH_3$ as 120 sccm,. The carrier lifetime enhanced as the thickness of $SiN_x$ increased due to improved passivation effect. To study the characteristics of $SiN_x$ with various gas ratios, the gas flow of $NH_3$ was changed from 40 sccm to 200 sccm with intervals of 40 sccm. The thickness of $SiN_x$ was fixed as 1000 ${\AA}$ and the gas flow of $SiH_4$ as 40 sccm. The refractive index of SiNx and the carrier lifetime were measured before and after heat treating at $650^{\circ}C$ to investigate their change by the firing process in solar cell fabrication. The index of refraction of SiNx decreased as the gas ratios increased and the longest carrier lifetime was measured with the gas ratio $NH_3/SiH_4$ of 3.

• Pediatric Infection and Vaccine
• /
• v.16 no.2
• /
• pp.191-198
• /
• 2009

Purpose : Breastfeeding should be recommended for infants born to mothers with chronic hepatitis B Infection after postexposure prophylaxis. However, high proportion of these mothers are reluctant to engage in breastfeeding in Korea. This survey was taken to identify the cause of that reluctance. Method : Questionnaires were given to mothers with chronic hepatitis B infection who were registered at the 'Hepatitis B Perinatal Transmission Prevention Program' operated by Korea Center for Disease Control and Prevention. They visited a community health center for blood sample collection and signed a consent paper. The questionnaires were sent to the mothers. Result : Among 839 mailed questionnaires, 114 were returned marked 'address unknown'. The overall reply rate was 17% (n=125). Among responders, 52% (n=62) were breastfeeding and 48% (n=60) were formula-feeding. The most influential factor for breastfeeding was the mother's own decision (75%) and the obstetrician's recommendation (17%). For formulafeeding mothers, their decisions were influenced by obstetricians (57%), and by their own thinking (28%). The relationship between breastfeeding and perinatal prophylaxis failure was recognized as 45% 'related' and 50% 'not-related'. A total of 91% of breastfeeding mothers replied that they will breast-feed again. Among formula-feeding mothers, 78% answered that they will breast-feed if they were known that 'there is no direct relationship between breastfeeding and perinatal prophylaxis failure'. Conclusion : Despite the fact that there is no direct relationship between breastfeeding and perinatal prophylaxis failure, many were reluctant to breast-feed. Healthcare professionals have influence over the mothers for decision making. It will be necessary to educate healthcare personnel so that they can make a conceptual change as well as to promote the fact to the general public.

• Clinical and Experimental Pediatrics
• /
• v.45 no.10
• /
• pp.1251-1262
• /
• 2002

Purpose : The purpose of this study is to assess and compare the stress of mothers and fathers in families with epileptic children, and to assess contributing factors to their stress. Methods : We used a family stress survey with 35 questionnaires to obtain data concerning the parents' perceived stress. Data were analyzed with SPSS 8.0 program using Pearson correlation coefficient, oneway ANOVA, and multiple range test. Results : The parents' stress level seemed not so high and there was no significant difference in stress level between mothers and fathers. There was no significant correlation between most demographic variables of the parents and parents' stress level. But the time of bringing epileptic children correlates positively with the stress level. Oneway ANOVA showed the differences of parents' stress level according to the education institution, seizure type, number of antiepileptic drugs, and the combined disabilities of the sufferer. Conclusion : The results of present study indicate that the stress level in the families with epileptic children may be influenced by some treatment-related characteristics of epileptic children such as seizure type, number of antiepileptic drugs, combined disabilities and the raising method of hospital expenses.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.3
• /
• pp.463-469
• /
• 2009

We performed the experimental study on the control of suspended dust in a cement packaging process for various ventilation systems. To effectively remove the dust generated in the cement packaging process, three different kinds of ventilation system, such as local exhaust ventilation, electrostatic scrubber, and local air supply system, were adopted. Dust concentrations in the packaging process were measured with the variation of the airflow rate of the ventilation systems and then their ventilation performance were evaluated. From the results, we knew that the ventilation performance was the best when the local exhaust ventilation and the electrostatic scrubber were simultaneously operated in the packaging process. In the electrostatic scrubber system, the effect of the airflow rate on the indoor dust removal efficiency was negligible so hat he system ust be operated at $2,700m^3/h$ for saving power consumption.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.43 no.3
• /
• pp.52-62
• /
• 2015

This study conducted an experiment to clarify the effect of rubber bands used as a root connector during the process of transplanting landscape trees on the development of the root system and the rooting process. The research period was four years, from April 2007 to April 2011, and the test conducted for this study was performed at the experimental field located at 398-2 Bangdong-ri, Sacheon-myeon, Gangneung-si, Gangwon-do. Twenty 15-year-old Pinus densiflora Siebold & Zucc. with good growth conditions were harvested and transplanted from the forest in Jebi-ri, Gujeong-myeon, Gangneung-si, Gangwon-do for the field experiment. A completely randomized design was applied for plot design, with 10 pines without rubber bands and 10 pines with rubber bands. Pinus densiflora for. multicaulis Uyeki was selected as the official tree of the pot test and was planted in a transparent pot to observe the development of the root system. A completely randomized design was applied for plot design, with 3 pines without rubber bands and 3 pines with rubber bands. The results of this research on the effect of rubber bands used as a root connector on root system development and the rooting process are as follows. 1. The rate of height growth in the field test was 4.1% lower in the trees with rubber bands when compared to trees without rubber bands. Trees with rubber bands were 4.2% wider than those without rubber bands in root diameter. The chlorophyll content was 6.8% higher in trees without rubber bands, but the rate of height growth, root diameter, and chlorophyll content were not significantly correlated. 2. In the comparison of fresh root weight in the field test, trees with rubber banding had roots weighing 1,740.0kg and those without rubber bands had roots weighing 1,433.3kg. Root dry weight was 522.3g in trees with rubber bands and 450.0g in those without rubber bands, but showed no significant difference depending on whether the rubber band was attached. 3. In a comparison of root number between surfaces touching and not touching the rubber band in trees with rubber banding, the surface touching the rubber band was observed to have more roots growing, the difference of which was deemed significant. 4. The shoot growth rate in the pot test was 1.1% higher in trees without rubber bands when compared with trees with rubber bands. The chlorophyll content was 0.02 higher in trees with rubber bands but the difference was not significant. 5. In the pot test, no significance was found in comparison of root number, root length, and root dry weight in trees with and without rubber bands. These test results imply that removing rubber bands as a connector does not present any significant effects on the ground growth or root development of transplanted pine trees. As it is shown that surface touching rubber bands grow more roots in trees with rubber bands, more active related research must be undertaken.