• Title/Summary/Keyword: Radio Technology

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Current Status and Future Prospects of Korean VLBI Network (KVN)

  • Jung, Taehyun;Sohn, Bong Won;So, Byunghwa;Oh, Chungsik;Je, Do-Heung;Byun, Do-Young;Jung, Dong-Kyu;Roh, Duk Gyoo;Lee, Euikyum;Kim, Hyo Ryoung;Kim, Hyun-Goo;Byun, Hyungkyu;Chung, Hyunsoo;Yim, In Sung;Kim, Jae-Young;Kim, Jaeheon;Yeom, Jaehwan;Shin, Jaesik;Park, Jeong-Je;Kim, Jeong-Sook;Hwang, Jungwook;Wajima, Kiyoaki;Song, Min-Gyu;Chung, Moon-Hee;Sakai, Nobuyuki;Lee, Sang-Hyun;Lee, Sang-Sung;Oh, Sej-Jin;Wi, Seog Oh;Kim, Seungrae;Kim, Soon-Wook;Lee, Sung-Mo;Kang, Yong-Woo;Minh, Young Chol;Kim, Young-Sik;Yun, Youngjoo
    • The Bulletin of The Korean Astronomical Society
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    • v.46 no.1
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    • pp.60.3-61
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    • 2021
  • The Korean VLBI Network (KVN) consists of three 21m radio telescopes installed in Seoul, Ulsan, and Jeju Island with the world's first 4-channel receiver that can observe four different frequencies (e.g., 22, 43, 86, 129 GHz) simultaneously. This receiving system of KVN is particularly effective in millimeter-wavelength VLBI (mm-VLBI) observations by compensating fast atmospheric fluctuations effectively. This technology is now being enhanced with a compact triple-band receiver, becoming the world standard for a mm-VLBI system. In 2020, KVN supported 54 observing programs (KVN: 28, EAVN: 26) including the 2nd KVN Key Science Program (KSP) which supports 8Gbps data recording rate and the East Asian VLBI Network (EAVN) programs. KVN also participated in the European VLBI Network (EVN) and GMVA (Global Millimeter VLBI Array) sessions regularly. Here, we report current status and future propsects of KVN.

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The need for mechanization in todays canal building program in korea and overseas (수로의 기계화 시공의 필요성)

  • Ha, Gordon P.wkins
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.21 no.2
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    • pp.21-27
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    • 1979
  • Canal construction is not the only area in which mechanization has advanced with great strides. All phases of the construction industry, including earthmoving, land clearing and levelling, road construction, and drainage and water control projects, have benefited from today's technological advancements. Lasers, an excellant example of advanced technology, have been refined for use as guidance systems for construction machinery, increasing accuracy and the speed of operation. The use of explosives by contractors is becoming more commonplace. One of the most valuable modern tools available today is the two-way radio. On today's sophisticated projects a single machine being down can frequently stop the progress of the entire project, delaying hundreds of men and machines from completing their assigned work for the day. The use of two-way radios in all the pickups and cars being used on a project facilitates communication so that emergency repairs can be effected immediately, and costly down time on any project can be reduced to a minimum. Not every construction project is suitable to mechanization. However, on the majority of projects mechanization has a great deal to offer the Korean contractor, and all contractors, in savings of time and money. Each and every project being considered by a contractor, should be closely examined for the most effective and efficient machinery application available. The International Commission on Irrigation and Drainage (ICID) has formed a committee on construction techniques being used in canal construction today. Two publications are now available describing the advances made in recent years. Standards for construction have been established for mechanized systems and this information is being distributed worldwide.

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Gamma-ray Irradiation on Radio Sensitivity in Yacon (Samallanthus sonchifolius (Poepp. & Endl.) H. Robinson) Breeding (돌연변이 육종을 위한 야콘의 최적 감마선 조사량)

  • Su Jeong Kim;Hwang Bae Sohn;Yul Ho Kim;Jung Hwan Nam;Jong Nam Lee;Dong Chil Chang;Jong Taek Suh
    • Proceedings of the Plant Resources Society of Korea Conference
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    • 2021.04a
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    • pp.27-27
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    • 2021
  • Yacon [Samallanthus sonchifolius (Poepp. & Endl.) H. Robinson], a member of Compositae plants, has sweet taste and crisp texture. Unlike other Andean root crops such as potato and sweet potato, the cultivation area of yacon has increased recently, since it is known to have large content of fructooligosaccharides (FOS). Since there are no yacon varieties bred in Korea, we have been trying to create new genetic resources using gamma-ray. The optimal gamma-ray dosage for mutation breeding in yacon was investigated. Crown bud and green bud of yacon were exposed to doses of gamma rays from 20 Gy to 80 Gy, and subsequently planted in a greenhouse. After 50 days of sowing, the survival rates and growth decreased rapidly at doses above 40 Gy, while all of crown bud individuals died above 60 Gy. The median lethal dose (LD50) of crown bud and green bud was 22.4 and 36.6 Gy, and the median reduction doses (RD50) for plant height, fresh weights, and tuberous root weight were 20-40 Gy, respectively. A dose of 20-40 Gy was found to be optimal for mutation breeding in yacon. Considering the growth factors, the optimum doses were determined to be within the range of 20-40 Gy for the selection of useful mutant lines. M2-M3 mutant lines were obtained from 20-60 Gy gamma-ray-irradiated M1 plants through clonal propagation. These mutant lines will be used for the development of a new variety of yacon plant with high FOS and no crack tuberous root.

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Mission-Oriented Conceptional Design of the Cube Satellite CNU Laser Unity Bus (CLUB) for Ground-Space Laser Research (지상-우주 레이저 연구를 위한 큐브위성 CLUB(CNU Laser Unity Bus)의 임무 중심 개념설계)

  • Seok-Min Song;Ho Sub Song;Chae-Ryeong Kim;Young-In Kang;Yang-Ha Ju;Mansoo Choi;Hyung-Chul Lim;Yu Yi
    • Journal of Space Technology and Applications
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    • v.4 no.1
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    • pp.48-61
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    • 2024
  • In this paper, we introduce the concept of the cube satellite Chungnam National University Laser Unity Bus (CLUB), which can provide an integrated infrastructure for various ground-space laser applications. With the advent of the new space era, the rapid expansion of space utilization has begun to reveal the limitations of conventional radio frequencies. As space missions diversify, lasers are garnering attention as a viable alternative. Between ground and space, lasers are applied in various fields including satellite laser ranging (SLR), laser weapons, and laser communication. However, laser used between the ground and space are significantly influenced by the Earth's atmosphere. Consequently, understanding the atmospheric effects on laser propagation is crucial. In particular, atmospheric turbulence, which refracts and distorts laser beams, intensifies closer to the Earth's surface, exerting a greater impact on the uplink than on the downlink. While downlink verification is facilitated by ground detection, verifying the uplink poses challenges due to the necessity of space-based detection. In response to these challenges, we propose the idea of cube satellite as a means to enhance understanding and verification of laser propagation in the uplink. Additionally, we present the results of conceptual design by analyzing requirements, focusing on mission design of the CLUB cube satellite, following the stages of systems engineering for systematic cube satellite development.

Recent Developments in Space Law (우주법(宇宙法)의 최근동향(最近動向))

  • Choi, June-Sun
    • The Korean Journal of Air & Space Law and Policy
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    • v.1
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    • pp.223-243
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    • 1989
  • The practical application of modern space science and technology have resulted in many actual and potential gains of mankind. These successes have conditioned and increased the need for a viable space law regime and the challenge of space has ultimately led to the formation of an international legal regime for space. Space law is no longer a primitive law. It is a modern law. Yet, in its stages of growth, it has not reached the condition of perfection. Therefore, under the existing state of thing, we could carefully say that the space law is one of the most newest fields of jurisprudence despite the fact that no one has so far defined it perfectly. However, if space law can be a true jurisprudential entity, it must be definable. In defining the space law, first of all, the grasp of it's nature iis inevitable. Although space law encompasses many tenets and facets of other legal discriplines, its principal nature is public international law, because space law affects and effects law relating intercourse among nations. Since early 1960s when mankind was first able to flight and stay in outer space, the necessity to control and administrate the space activities of human beings has growingly increased. The leading law-formulating agency to this purpose is the United Nation's ad hoc Committee on Peaceful Uses of Outer Space("COPUOS"). COPUOS gave direction to public international space law by establishing the 1963 Declaration of Legal Principles Governing the Activities of the States in the Exploration and Use of Outer Space("1963 Declaration"). The 1963 Declaration is very foundation of the five international multilateral treaties that were established successively after the 1963 Declaration. The five treaties are as follows: 1) The Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space including Moon and other Celestial Bodies, 1967. 2) The Agreement on the Rescue of Astronauts, the Return of Astronauts, and the Return of Objects Launched into Outer Space, 1968. 3) The Convention on International Liability for Damage Caused by Space Objects, 1972. 4) The Convention on Registration of Objects Launched into Outer Space, 1974. 5) The Agreement Governing Activities of States on the Moon and Other Celestial Bodies: Moon Treaty, 1979. The other face of space law is it's commercial aspect. Space is no longer the sole domination of governments. Many private enterprise have already moved directly or indirectly into space activities in the parts such as telecommunications and space manufacturing. Since space law as the public international law has already advanced in accordance with the developments of space science and technology, there left only a few areas untouched in this field of law. Therefore the possibility of rapid growth of space law is expected in the parts of commerical space law, as it is, at this time, in a nascent state. The resources of the space environment are also commercially both valuable and important since the resources include the tangible natural resources to be found on the moon and other celestial bodies. Other space-based resources are solar energy, geostationary and geosynchronous orbital positions, radio frequencies, area possibly suited to human habitations, all areas and materials lending themselves to scientific research and inquiry. Remote sensing, space manufacturing and space transportation services are also another potential areas in which commercial. endeavors of Mankind can be carried out. In this regard, space insurance is also one of the most important devices allowing mankind to proceed with commercial space venture. Thus, knowlege of how space insurance came into existence and what it covers is necessary to understand the legal issues peculiar to space law. As a conclusion the writer emphasized the international cooperation of all nations in space activities of mankind, because space commerce, by its nature, will give rise many legal issues of international scope and concern. Important national and world-community interests would be served over time through the acceptance of new international agreements relating to remote sencing, direct television broadcasting, the use of nuclear power sources in space, the regularization of the activities of space transportation systems. standards respecting contamination and pollution, and a practical boundary between outer space and air space. If space activity regulation does not move beyond the national level, the peaceful exploration of space for all mankind will not be realized. For the efficient regulation on private and governmental space activities, the creation of an international space agency, similar to the International Civil Aviation Organization but modified to meet the needs of space technology, will be required. But prior to creation of an international organization, it will be necessary to establish, at national level, the Office of Air and Space Bureau, which will administrate liscence liscence application process, safety review and sale of launch equipment, and will carry out launch service.

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Study of Quality Control of Traditional Wine Using IT Sensing Technology (IT 센싱 기술을 이용한 전통주 발효의 품질관리 연구)

  • Song, Hyeji;Choi, Jihee;Park, Chan-Won;Shin, Dong-Beom;Kang, Sung-Soo;Oh, Sung Hoon;Hwang, Kwontack
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.44 no.6
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    • pp.904-911
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    • 2015
  • The objective of this study was to investigate the quality characteristics of traditional wine using an radio-frequency identification (RFID) system annexed to a fermenter. In this study, we proposed an RFID-based data transmission scheme for monitoring fermentation of traditional alcoholic beverages. The pH, total acidity, total sugar, soluble sugar, free sugar, alcohol content, and organic acids of were investigated and subjected to fermentation of traditional alcoholic beverages three times. The pH ranged from 7.98, 7.95, and 7.68 at day 0, decreased drastically to 3.31~2.96 at day 2, and then slowly increased to the end point, finally reaching 3.34 at day 20. Acidity tended to increase quickly with time, especially for all samples after day 2. The fermentation environment induced a sudden increase acidity in reactants and indicated a low pH. The total sugars during fermentation quickly decreased to the range of 20.3, 22.43, and 19.2% at day 2, and the slope of reduction steadily decreased to 5.1, 6.1, and 4.8% at day 10. On the other hand, the alcohol content showed the reverse trend as total sugars. The alcohol content also showed the same pattern as total acids, showing the highest alcohol content of 17.3% (v/v) on day 20. In this study on traditional wine fermentation using an RFID system, we showed that pH, soluble sugar, and alcohol content can be adopted as key indicators for quality control and standardization of traditional wine manufacturing.

Evaluation of Antenna Pattern Measurement of HF Radar using Drone (드론을 활용한 고주파 레이다의 안테나 패턴 측정(APM) 가능성 검토)

  • Dawoon Jung;Jae Yeob Kim;Kyu-Min Song
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.35 no.6
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    • pp.109-120
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    • 2023
  • The High-Frequency Radar (HFR) is an equipment designed to measure real-time surface ocean currents in broad maritime areas.It emits radio waves at a specific frequency (HF) towards the sea surface and analyzes the backscattered waves to measure surface current vectors (Crombie, 1955; Barrick, 1972).The Seasonde HF Radar from Codar, utilized in this study, determines the speed and location of radial currents by analyzing the Bragg peak intensity of transmitted and received waves from an omnidirectional antenna and employing the Multiple Signal Classification (MUSIC) algorithm. The generated currents are initially considered ideal patterns without taking into account the characteristics of the observed electromagnetic wave propagation environment. To correct this, Antenna Pattern Measurement (APM) is performed, measuring the strength of signals at various positions received by the antenna and calculating the corrected measured vector to radial currents.The APM principle involves modifying the position and phase information of the currents based on the measured signal strength at each location. Typically, experiments are conducted by installing an antenna on a ship (Kim et al., 2022). However, using a ship introduces various environmental constraints, such as weather conditions and maritime situations. To reduce dependence on maritime conditions and enhance economic efficiency, this study explores the possibility of using unmanned aerial vehicles (drones) for APM. The research conducted APM experiments using a high-frequency radar installed at Dangsa Lighthouse in Dangsa-ri, Wando County, Jeollanam-do. The study compared and analyzed the results of APM experiments using ships and drones, utilizing the calculated radial currents and surface current fields obtained from each experiment.

An Exploratory Study of Purchasing Decision Making and Adoption on the RFID Purchasing Customer (RFID 구매고객의 구매 의사결정과 수용에 대한 탐색적 연구)

  • Seo, Pil-Su;Jang, Jang-Yi;Shim, Kyeng-Su
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
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    • v.3 no.4
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    • pp.89-116
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    • 2008
  • RFID (Radio Frequency Identification) is regarded as a core technology of ubiquitous computing. Although it has some technical limitations such as technological standardization of RFID tags as well as economical limitations, many companies around the world have already accepted RFID to improve their management efficiency. In this regard, this study is to meet with results that the adoption of RFID technology willbring opportunities that companies' operational process are improved and customer satisfaction is highly strengthened. This research focuses on providing more understanding for building RFID marketing strategy to suppliers who want to sell their RFID products to customers through analyzing purchasing process. The findings are as follows; First, the study shows that buying center members usually take product reliability and precision of technical specification in the case of new-task buying situation while they put their first purchasing priority on prices in the straight rebuy. Second, the finding presents that in new-task buying situation and the straight rebuy purchasing personnel get information about new products through product performance test, organizational engineers, opinions from other companies' purchasing personnel, and checking out samples. Third, this research demonstrates when it comes to purchasing risk in their first purchasing, the persons who are in charge of material purchasing are inclined to be aware of the risk most in technical problems, followed by financial problems and time delay problems in order. And in addition to those risks are mentioned above, once-again-purchasers take the risk like an opportunity loss for better products into consideration. Fourth, the study shows that the role of concerning departments makes no difference in each purchasing stage. Accordingly marketers need to beef up the differentiated strategy to persuade their customers Fifth, the findings of this study demonstrate that purchasing decision making is much influenced by the final users. So suppliers are supposed to perform the most active marketing strategy at the first stage of purchasing through various resources. Finally, the study presents that the suppliers who will have had close relationships with their customers need to give consistent information to them so that their customers can have lower motive in purchasing products from competitors.

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Analysis on the volume variation of bag-net in set-net by acoustic telemetry (음향 텔레메트리에 의한 정치망 원통의 체적 변화 해석)

  • Tae, Jong-Wan;Shin, Hyeon-Ok
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.40 no.2
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    • pp.115-125
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    • 2004
  • An experiment to measure the volume variation of bag net in a set-net by acoustic telemetry system was conducted in Jaran Bay, Gosung, Korea on 10 April to 23 April 2003. The long baseline telemetry system consists of three radio-acoustic linked positioning (RAP) buoys, a time controller with a personal computer and seven pingers. Six pingers were attached on the bottom of the bag-net and the other one was fixed on the sea bed. The results obtained are summarized as follows : 1. The average RAP buoy fixing errors of x-axis, y-axis, and z-axis were 0.2m, 0.4m, and 0.1m, respectively. 2. In the neap tide the minimum and maximum volume of the bag-net on 11 April 2003 were 4,173$m^3$(17:00) and 4,757$m^3$(12:00), respectively. The average current direction and speed at those times were 99.9$^{\circ}$, 12.9cm/s and 104.0$^{\circ}$, 2.4cm/s, respectively. 3. In the spring tide on 17 April 2003, the minimum and maximum volume were 2,016$m^3$(18:30) and 4,454$m^3$(15:00), respectively. The average current direction and speed at those times were 315.6$^{\circ}$, 16.1cm/s and 289.0$^{\circ}$, 5.7cm/s, respectively. 4. In conclusion the maximum variation of the volume on 17 April to 20 April 2003 was 3,552$m^3$ and it was larger 1.4 times than time on 11 April to 16 April 2003.

The Evaluation of Usefulness of Two Times Elution a Day of $^{99m}Tc$ Using $^{99}Mo$-$^{99m}Tc$ Generator ($^{99m}Tc$ 발생기의 24시간 내 2회 용출의 유용성 평가)

  • Kim, Jeong-Ho;Seo, Han-Kyung;Jeong, Yeong-Hwan;Kim, Yeong-Su;Kim, Byung-Cheol;Gwon, Yong-Ju;Lee, Jeong-Ok;Park, Yeong-Sun;Kim, Dong-Yun
    • The Korean Journal of Nuclear Medicine Technology
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    • v.14 no.2
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    • pp.83-86
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    • 2010
  • Purpose: The Molybdenum which is the raw material of $^{99}Mo$-$^{99m}Tc$ generator (generator) is produced from the nuclear reactor. However, output has dwindled as the two nuclear reactors supplying the bulk of radioactive material-one in Chalk River, Ontario and the other in Petten, the Netherlands-have been closed for repairs or maintenance. This resulted in the enhancement of its price. Therefore we have tried to seek the new method which could run generator to increase activity of $^{99m}Tc$ in this study. Materials and Methods: The $^{99m}Tc$ activity obtained from 5 times elution for 5 days from Monday to Friday using two generators was compared with 10 times elution. Appearance test, pH test, LAL test, sterility test, chemical impurity(Al) test, radio chemical purity test, ratio of $^{99}Mo$/$^{99m}Tc$ activity test have been done to check the stability of $^{99m}Tc$ eluting from generator respectively. Results: The $^{99m}Tc$ activity obtained from 5 times elution for 5 days was 168.2 GBq (4545 mCi) and 10 times was 230.5 GBq (6230 mCi). All quality control tests were within normal limit. Conclusion: We got to know that 2 times elution a day obtained more $^{99m}Tc$ activity than one time elution in this study.

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