• Title/Summary/Keyword: High frequency Link

Search Result 324, Processing Time 0.025 seconds

Design of the PAM with High Linearity and Efficiency for Wibro (고선형성, 고효율의 Wibro용 PAM 설계)

  • Oh Inn-Yeal;Kim Tae-Soo;Rhe Kun-Moo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.17 no.6 s.109
    • /
    • pp.519-528
    • /
    • 2006
  • This thesis is regarding of fabricating wibro PAM. First of all, we need to set specification based on link budget for wibro communication circumstance in order to develop PAM, then we decided specification concerning of wibro PAM by considering TTAS_Ko_06_0082R1 which is standarded in Korea, and IEEE Std. 802. 16d/e which is international standard. We selected the Doherty structure to increase efficiency, and pre-distorter structure to increase linearity. The fabricated PAM has not only a result of $26.5dB{\pm}1.0dB$ gain characteristics and maximum of -14 dB return loss characteristics in full frequency bands and full output ranges, but also a result of 37 dBc at 4 tone IMD characteristics which is improved result of 843 and a result of 31 dBc spurious characteristics which is improved result of 5 dB at 4.77 MHz offset point in status of having 27 % efficiency in the 26 dBm high power amplifier output signal. We confirmed the suggested structure is better than others by comparing with normal structure, balanced structure and Doherty structure without predistorter.

Study on the Air Insulation Design Guideline for ±500 kV Double Bipole Transmission Line with Metallic Return Conductor (도체귀로형 ±500 kV Double Bipole 송전선로 공기절연에 관한 연구)

  • Shin, Kooyong;Kwon, Gumin;Song, Seongwhan;Woo, Jungwook
    • KEPCO Journal on Electric Power and Energy
    • /
    • v.5 no.3
    • /
    • pp.141-147
    • /
    • 2019
  • Recently, the biggest issue in the electricity industry is the increase in renewable energy, and various technologies are being developed to ensure the capacity of the power system. In addition, super-grids linking power systems are being pushed to utilize eco-friendly energy between countries and regions worldwide. The HVDC transmission technology is required to link the power network between regions with different characteristics of the power system such as frequency and voltage. Until now, Korea has applied HVDC transmission technology that connects mainland and Jeju Island with submarine cables. But, the HVDC transmission technology is still developing for long-distance high-capacity power transmission from power parks on the east coast to load-tight areas near the metropolitan area. Considering the high population density and mountainous domestic environment, it is pushing for commercialization of the design technology of the ${\pm}500kV$ Double Bipole with metallic return wire transmission line to transmit large-scale power of 8 GW using minimal right of ways. In this paper, the insulation characteristics were studied for the design of double-bipole transmission tower with metallic return wire, which is the first time in the world. And the air insulation characteristics resistant to the various overvoltage phenomena occurring on transmission lines were verified through a full-scale impulse voltage test.

Designing and Realizing the Ground Station Receiver Low Noise Amplifier of the Next-Generation Aeronautical Surveillance System (차세대 항공 감시시스템(ADS-BES) 지상국 수신기 저잡음 증폭기 설계 및 구현)

  • Cho, Ju-Yong;Yoon, Jun-Chul;Park, Chan-Sub;Park, Hyo-Dal;Kang, Suk-Youb
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.17 no.10
    • /
    • pp.2273-2280
    • /
    • 2013
  • This article introduces the next-generation air surveillance system and investigates how to design of front-end low noise amplifier of the ground station receiver. In consideration of the international standard documentation and the performance of existing products, the study conducts the link budget on the entire system so that it can be competitive in terms of receive sensitivity or reliability. To obtain a proper low noise amplifier, standards of design are decided so that such factors as gain, gain flatness, and reflective loss can be optimal. In its design, the bias circuit appropriate for the characteristics of low power, low noise, or high gain was built, and according to the results of the simulation conducted after the optimal design, its gain was 16.24dB, noise factor was 0.36dB, input-output reflective loss was -18dB and -28dB each, and frequency stability was 1.11. According to the results measured after the design, its gain was 17dB, noise factor was 0.51dB, gain flatness was 0.23dB, and input-output reflective loss was -18.28dB and -24.50dB each, so the results gained were suitable for building the overall system.

The Effect of Wireless Channel Models on the Performance of Sensor Networks (채널 모델링 방법에 따른 센서 네트워크 성능 변화)

  • 안종석;한상섭;김지훈
    • Journal of KIISE:Information Networking
    • /
    • v.31 no.4
    • /
    • pp.375-383
    • /
    • 2004
  • As wireless mobile networks have been widely adopted due to their convenience for deployment, the research for improving their performance has been actively conducted. Since their throughput is restrained by the packet corruption rate not by congestion as in wired networks, however, network simulations for performance evaluation need to select the appropriate wireless channel model representing the behavior of propagation errors for the evaluated channel. The selection of the right model should depend on various factors such as the adopted frequency band, the level of signal power, the existence of obstacles against signal propagation, the sensitivity of protocols to bit errors, and etc. This paper analyzes 10-day bit traces collected from real sensor channels exhibiting the high bit error rate to determine a suitable sensor channel model. For selection, it also evaluates the performance of two error recovery algorithms such as a link layer FEC algorithm and three TCPs (Tahoe, Reno, and Vegas) over several channel models. The comparison analysis shows that CM(Chaotic Map) model predicts 3-time less BER variance and 10-time larger PER(Packet Error Rate) than traces while these differences between the other models and traces are larger than 10-time. The simulation experiments, furthermore, prove that CM model evaluates the performance of these algorithms over sensor channels with the precision at least 10-time more accurate than any other models.

Recruitment Potential of Cyanobacterial Harmful Algae (Genus Aphanizomenon) in the Winter Season in Boryeong Reservoir, Korea: Link to Water-level Drawdown (동계 보령호에서 수위 강하와 연계된 유해 남조류 Aphanizomenon sp.의 재입 잠재성)

  • Shin, Jae-Ki;Jeon, Gyeonghye;Kim, Youngsung;Kim, Mi-Kyung;Kim, Nan-Young;Hwang, Soon-Jin
    • Korean Journal of Ecology and Environment
    • /
    • v.50 no.3
    • /
    • pp.337-354
    • /
    • 2017
  • Cyanobacteria Aphanizomenon population is widely distributed in the world, and well known as harmful algae by producing toxins and off-flavor materials, thus belonging to one of the taxa that became more interested in the field of limnoecology. In this study, the frequency, intensity, and duration of Aphanizomenon occurrence were increased with the abnormal drawdown of water level in the winter in Boryeong Reservoir, and the spatial and temporal characteristics of them are compared with each other in the perspective of hydrometeorology (1998 to 2017) and limnology (2010 to 2017). In Korea, Aphanizomenon flourished mainly in high temperature, and the appearance in the low temperature was rare in total five times. The harmful cyanobacteria Aphanizomenon was observed in the low temperature (December to February) in Boryeong Reservoir from 2014, and then reached a maximum value of $2,160cells\;mL^{-1}$ in January 2017. In addition, the period exceeding $1,000cells\;mL^{-1}$ at this time was more than 3 months. This was simultaneously associated with abnormal water level fluctuation in the low temperature ($<10^{\circ}C$). The large drawdown of water level in the winter season has the potential to promote or amplify the germination and development of harmful algae. Also, subsequent water quality and ecological impacts(e.g., algal toxins and off-flavor substances) need to be considered carefully.

The study of metabolic risk factors and dietary intake in adolescent children by the status of mothers' metabolic syndrome: Using the data from 2007-2010 Korean National Health and Nutrition Examination Survey (어머니의 대사증후군 상태에 따른 청소년 자녀의 대사위험지표 및 식생활 요인에 대한 연구: 2007~2010년 국민건강영양조사 자료를 이용하여)

  • Kwon, SoYeon;Park, Mijung;Song, YoonJu
    • Journal of Nutrition and Health
    • /
    • v.46 no.6
    • /
    • pp.531-539
    • /
    • 2013
  • The prevalence of metabolic syndrome (MetS) in Korea has been increasing in adults, as well as in adolescents. Recently the prevalence of MetS in children has been reported to strongly link that of MetS in parents. Families are known to share similar food environment so that eating habits of parents closely resemble that of the children's. Therefore, the aim of this study to examine metabolic risk factors and dietary intake in children by with respect to mother's metabolic syndrome, based on the data from Korean National Health and Nutrition Examination Survey (KNHANES) 2007-2010. Using the household variable and the eldest child per household, 1,341 pairs of mothers and children were selected. The mothers were defined by MetS criteria, and then the children were classified into the following three groups in accordance to the mothers' MetS; children whose mothers had none, 1-2, and 3 or more components of MetS. All dietary data were evaluated using the data from a food frequency questionnaire. The mean age was $42.6{\pm}4.2$ years for the mothers, and $14.9{\pm}2.0$ years for the children. Children whose mothers had 3 or more components of MetS showed a significantly higher prevalence of overweight and higher level of fasting triglyceride; conversely, they showed a lower level of serum HDL-cholesterol compared to the other two groups. Regarding an agreement of food consumption between the mothers and children, most food groups showed high agreement, except in the category of beverages. Regarding the dietary habits and family meals, children whose mothers had 3 or more components of MetS were more likely to skip breakfast and less likely to have family meals at breakfast or snack. In conclusion, the children's metabolic risk factors and dietary factors were different with respect to the status of mothers' MetS. Further studies are necessary to examine the causal effect of family environment in children's health status.

Properties of a Social Network Topology of Livestock Movements to Slaughterhouse in Korea (도축장 출하차량 이동의 사회연결망 특성 분석)

  • Park, Hyuk;Bae, Sunhak;Pak, Son-Il
    • Journal of Veterinary Clinics
    • /
    • v.33 no.5
    • /
    • pp.278-285
    • /
    • 2016
  • Epidemiological studies have shown the association between transportation of live animals and the potential transmission of infectious disease between premises. This finding was also observed in the 2014-2015 foot-and-mouth disease (FMD) outbreak in Korea. Furthermore, slaughterhouses played a key role in the global spread of the FMD virus during the epidemic. In this context, in-depth knowledge of the structure of direct and indirect contact between slaughterhouses is paramount for understanding the dynamics of FMD transmission. But the social network structure of vehicle movements to slaughterhouses in Korea remains unclear. Hence, the aim of this study was to configure a social network topology of vehicle movements between slaughterhouses for a better understanding of how they are potentially connected, and to explore whether FMD outbreaks can be explained by the network properties constructed in the study. We created five monthly directed networks based on the frequency and chronology of on- and off-slaughterhouse vehicle movements. For the monthly network, a node represented a slaughterhouse, and an edge (or link) denoted vehicle movement between two slaughterhouses. Movement data were retrieved from the national Korean Animal Health Integrated System (KAHIS) database, which tracks the routes of individual vehicle movements using a global positioning system (GPS). Electronic registration of livestock movements has been a mandatory requirement since 2013 to ensure traceability of such movements. For each of the five studied networks, the network structures were characterized by small-world properties, with a short mean distance, a high clustering coefficient, and a short diameter. In addition, a strongly connected component was observed in each of the created networks, and this giant component included 94.4% to 100% of all network nodes. The characteristic hub-and-spoke type of structure was not identified. Such a structural vulnerability in the network suggests that once an infectious disease (such as FMD) is introduced in a random slaughterhouse within the cohesive component, it can spread to every other slaughterhouse in the component. From an epidemiological perspective, for disease management, empirically derived small-world networks could inform decision-makers on the higher potential for a large FMD epidemic within the livestock industry, and could provide insights into the rapid-transmission dynamics of the disease across long distances, despite a standstill of animal movements during the epidemic, given a single incursion of infection in any slaughterhouse in the country.

Current Status of the Implementation of Convergence Education in Primary and Secondary Schools (초·중등학교의 융합교육 운영 현황 실태조사)

  • Kwon, Hyuksoo;Kim, Eojin;Park, Hyun Ju;Bae, Youngkwon;Lee, Dongkuk;Lee, Hyungdong;Lee, Hyonyoung;Choi, Sung-Youn;Ham, Hyung-In
    • Journal of Science Education
    • /
    • v.45 no.3
    • /
    • pp.336-348
    • /
    • 2021
  • The goal of this study is to investigate the current status of implementation of convergence education in elementary, middle, and high schools. A survey was conducted on 871 in-service teachers nationwide, and frequency analysis was conducted by school level. Key findings are as follows: first, 449 (51.5%) are found to practice convergence education. Second, the reason for implementing convergence education is the voluntary effort of teachers and the educational necessity for the future society. Third, it was found that convergence education is being implemented centered on science, arts, and social studies as a link between subjects in regular curriculum hours. Fourth, 270 (64%) of teachers who implemented convergence education in response to COVID-19 performed online convergence education, and experienced difficulties in creating class materials and communicating with students. Fifth, the excessive work of teachers, insufficient support for teacher training and research group activities, and lack of various convergence education programs are suggested as reasons for not implementing convergence education. This study hopes to provide implications for policy and implementation for revitalizing convergence education.

The Effect of the Shift Work on Drinking and the Mediating Effect of Sleep (교대근무가 음주에 미치는 영향 및 수면의 매개효과)

  • Jeong, Heeju;Kong, Ji-Sook;Kim, Mi Kyung;Kim, Seok Hyeon
    • Korean Journal of Psychosomatic Medicine
    • /
    • v.29 no.2
    • /
    • pp.111-120
    • /
    • 2021
  • Objectives : Shift work has been known to cause various health problems by making it difficult for humans to adapt to their natural circadian rhythms. In particular, shift workers tend to complain of sleep difficulties associated with work schedules, and sometimes use alcohol as a self-medication to induce sleep. To date, no clear mechanism has been identified regarding the link between shift work and sleep, between shift work and drinking. This study aims to confirm the relationship between shift work and sleep, and to analyze whether the change in sleep caused by shift work causes drinking. Methods : This study included 11360 people (5704 men and 5656 women) among the Korean National Health and Nutrition Survey data in 2014, 2016 and 2018. The work type between 6am-6pm was defined as day work, and other work types were defined as shift work. Using logistic regression analysis, the relationship between shift work and sleep quality, shift work and high risk drinking, drinking amount at 1 time, drinking frequency were analyzed. In addition, we analyzed whether sleep mediates the relationship between shift work and drinking using mediated analysis. Results : Shift work showed a significant negative relationship with sleep quality in men and women (male OR=1.37, 95% CI 1.11-1.70, female OR=1.26, 95% CI=1.05-1.50). There was no significant relationship between shift work and alcohol in the case of men, but in the case of women, there was a significant positive relationship between shift work and the number of alcohol consumption (OR=1.34, 95% CI=1.04-1.72). When mediation analysis was conducted, it was found that women's sleep quality partially mediated the relationship between shift work and the frequency of drinking. Conclusions : The results of this study suggest that shift work causes sleep difficulties, and in the case of women, drinking can be induced through the partial mediating effect of sleep. Considering that women are more likely to choose drinking as a coping method for sleep problems, more active interventions for female shift workers are needed.

An Analysis of Referrals, Nursing Diagnosis, and Nursing Interventions in Home Care - Wonju Christian Hospital Community Health Nursing Service - (가정간호 기록지 분석 - 원주기독병원 가정간호 보건활동을 중심으로 -)

  • Suh, Mi-Hae;Huh, Hae-Kyung
    • Journal of Home Health Care Nursing
    • /
    • v.3
    • /
    • pp.53-66
    • /
    • 1996
  • Home Health Care is one part of the total health care system. It includes health care services that link the hospital to the community. While it is important for early discharge patients, home care is also important for people with chronic illnesses or handicapping conditions. In 1989 the Korean government passed a law that opened the way for formal development of home health care services beginning with education programs to certify nurses for home care, and then demonstration home care services. Part of the mandate of the demonstration projects was evaluation of home care services. This study was done in order to provide basic data that would contribute to the development of records that could be used for evaluation through a retrospective audit and to examine the care that had been given in Home Care at Wonju Christian Hospital over a twenty year period from 1974 to 1994. The purposes of the study were : to identify to characteristics of the clients who had received home care, to identify the reasons for client referrals, to identify the nursing problems of these clients, to identify the nursing care provided to these clients, and to identify differences in these areas over the twenty year period. The study was a descriptive study involving a retrospective audit of the client records. Demographic data on all clients were included : 4,171 clients from 2,564 families. Data on referrals, nursing diagnosis and nursing interventions were from even numbered records which had a patient problem list included in the record, 2,801 clients, Frequencies and ANOVA were used in the analysis. The results of the study showed that the majority of the clients were from Wonju city /county. There were more women than men related to the high number of postpartum clients(1,300). The high number of postparttum clients and newborns was also evident in the age distribution. An the number of maternal-child clients decreased over the 20 years, the mean age of the clients increased significantly. Other factors also contributed to this change ; as increasing number of clients with brain injuries or with cancer, and fewer children with burns, osteomyelitis and tuberculosis. There was a decrease in the mean number of visits and mean length of coverage, reflecting a movement towards a short term acute care model. The number of new clents dropped sharply after 1985. The reasons for this are : the development of other treatment alternatives for clients, the establishment of an active wellbaby clinic, many more options plus a decreasing number of new cases of Hansen's Disase, and insurance that allows people with burns to be kept in hospital until skin grafts are healed. Socioeconomic changes have resulted in an increase in the number of cases of cancer, stroke, head injuries following car accidents, and of diabetes. Of the 2,801 client records, 2,541(60.9%) contained a written referral but for 1,802 it contained only the medical diagnosis. The number of records with a referral requesting specific nursing care was 739(29.1%). Many family members who were identified as in need of nursing care had no written referral. Analysis of the patient problem list showed that 41.9% of the enteries were nursing diagnoses. Others incuded medical diagnosis, symptoms, and plans. The most frequently used diagnoses were alteration in nutrition, less than body requirements(115 entries), alteration in skin integrity(114), knowledge deficit(111), pain(78), self-care deficit(66), and alteration in pattern of urinary elimination(50). These are reflected in the NANDA categories for which the highest number of diagnosis was in the Exchanging pattern(446), followed by Moving(178), Feeling(136) and Knowing (115). Analysis of the frequency of interventions showed that exercise and teaching about exercise was the most frequent intervention, followed by teaching concering the need for follow-up care, checking vital signs, managing nutritional problems, managing catheters, giving emotional support, changing dressings, teaching about medication, teaching (subject not specified), teaching about diet, IM and IV medications or fluid, and skin care, in that order. Recommendations included: development of a record that would allow for efficient recording of frequently used nursing diagnoses and nursing interventions: expansion of the catchment area for Home Care at Wonju Christian Hospital ; expansion of the service to provide complication prevention, rehabilitation services, and support to increase the health maintenance /health promotion of the people being served as well as providing client dentered care ; and development of a clinical record that will allow efficient data collection from records, even though the recording is done by a variety of health care providers.

  • PDF