• 신재생에너지
• /
• 제7권2호
• /
• pp.36-42
• /
• 2011

The wind speed at the altitude around 300 m is much higher and less variable than at the altitude around 80 m which is the same height of the MW class tower turbine's hub height. The wind power density is increased 0.37 W/$m^2$ per meter at the altitude around 6 to 7 km and 0.25 W/$m^2$ per meter at the altitude around 80 to 500 m. There are two types of power generation systems using lifting bodies. The one is that The generator is installed in the ground station and stretched into the lifting body through the tether. The other is that the generator is installed in the lifting body and stretched into the ground station through the tether. Many kinds of lifting bodies are also researched in the world, called kites, wings, single or twin aerostat, and so on. This article introduced the technical development status and the market prospects of the high altitude wind power generation system all over the world in detail.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
• /
• pp.57-60
• /
• 2001

CATV is the abbreviation for Cable Television. General CATV is a way of multi-channel sending images, voices and music including stillness image as well as characters to public receivers through electrical cable communication system. In the beginning, master antennas were people can not receive TV signal well. TV programs were received from master antennas to TVs in each house. Ground connection began by experimenting lightning with the use of a kite and it means electric appliances, communication equipments, measuring instruments and so on connecting the Earth in order to flow away overcharged electricity. There are two kinds of earth connection: Power Ground and Signal Ground. Power Ground is for preventing an electric shock and in general there's no current in the connector. However in an accident, there's a quick flow of electricity out to the Earth. Signal Ground is not only for the safety of appliances but also for the safety of equipment operation. This paper is about connection for noise and interference reduce in order to prevent wrong operation and distortion of signal in the electrical appliances which can take place in CATV.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 추계학술대회 논문집
• /
• pp.57-60
• /
• 2001

CATV is the abbreviation for Cable Television. General CATV is a way of multi-channel sending images, voices and music including stillness image as well as characters to public receivers through electrical cable communication system. In the beginning, master antennas were people can not receive TV signal well. TV programs were received from master antennas to TVs in each house. Ground connection began by experimenting lightning with the use of a kite and it means electric appliances, communication equipments, measuring instruments and so on connecting the Earth in order to flow away overcharged electricity. There are two kinds of earth connection: Power Ground and Signal Ground. Power Ground is for preventing an electric shock and in general there's no current in the connector. However in an accident, there's a quick flow of electricity out to the Earth. Signal Ground is not only for the safety of appliances but also for the safety of equipment operation. This paper is about connection for noise and interference reduce in order to prevent wrong operation and distortion of signal in the electrical appliances which can take place in CATV.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 제38회 하계학술대회
• /
• pp.294-295
• /
• 2007

80년대 초에 개발된 CD(Compact Disc) Disc는 지난 27여 년간 급속한 발전을 하였다. 95년에 DVD가 발표되면서 영화 Title제작이 되어 우리는 안방에서 고화질의 DVD를 감상할 수 있었다. CD-R(Recordable) 로부터 시작된 기록 기술은 CD-RW를 거쳐 DVD-Recordable, DVD-ReWritable 및 DVD-RAM, Light Scribe등 거쳐 BD(Blu-Ray) 기술에 까지 이르게 되었다. 광 Disc 기술은 3가지 분야로 나눌 수 있다. 안정된 제어를 위한 Servo 기술, Mechanical 기술, PC와communication 할 수 있는 Interface 기술 등으로 나눌 수 있다. Servo 제어 기술은 다음과 같이 4가지 분야로 구성되어 있다. Focus Servo, Tracking Servo, Sled Servo, Spindle Servo. Disc 회전을 제어를 담당하고 있는 Spindle Servo Block에서는 Hall Sensor를 이용하여 Disc의 회전을 Count하여 Feedback 하였다. 그러나 갈수록 심화 되고 있는 가격 경쟁 상황에서 Hall Sensor를 대체하여 회전수를 Conut하는 방법이 필요 하였다. BEMF(역기전력)을 이용한 Zero Crossing 방법이 이를 대체 하였지만, Motor의 전기적인 특성 편차 등에 안정된 control이 안되어서, Motor를 관리하는 방법으로 진행되어 왔다. 이것은 생산 Loss로 이어져서 Hall Sensorless의 장점을 훼손하게 되었다..본 논문에서는 이러한 Sensorless Type Spindle Motor의 문제점에 대해 Common 단자를 이용하여 안정된 제어 방법을 제안 한다. less Type의 문제점인 초기 기동 문제를 Common 단자를 이용하여 안정되게 Spindle motor를 Control 하는 방법에 대해 연구 하고자 한다.

• 한국전자통신학회논문지
• /
• 제15권5호
• /
• pp.813-818
• /
• 2020

본 연구는 초단파 대역에서의 표적 반사 신호 특성 및 분석에 대한 연구이다. 사전에 목표물에 대한 RCS 특성을 CST 전자기 해석툴을 사용하여 분석하고 Bi-Static 방법으로 목표물을 탐지하여 신호대 잡음비의 변화에 대해서 시험하였다. 시험결과는 사전 입사각도에 따른 RCS 분석에 대한 결과와 같이 목표물에 반사되는 신호 탐지에 대한 신호대 잡음비 특성이 큰 변동이 없는 유사한 결과를 보여준다. 향후 본 연구를 통하여 X 대역에 비하여 파장이 상대적으로 큰 VHF/UHF 대역 레이다의 표적에 대한 RCS 분석 및 등의 표적 탐지에 대한 특성 기술에 활용할 예정이다.

• 한국지역사회생활과학회지
• /
• 제17권4호
• /
• pp.175-197
• /
• 2006

This study aims to assess the traditional knowledge on seasonal customs and its characteristics for practical use. The Delphi method and correspondence analysis were hired to collect and analysis the data. Twenty six professionals for the Delphi participated in three-round process. The followings were concluded. The number of items valuing and resourcing for seasonal customs. were 118(40 for folks and ceremonies, 53 for foods. 25 for plays) on Delphi results. For example are Bokjori, Dano fm, Bokjumeoni, Chuseok, Tano festival, New Year Card, washing hair with an iris, Soup with rice cake, Boiled rice with five cereals, Rice and red-bean porridge, Kimchi-making for the winter, Sharing walnut with friends, Game of yut, Playing kite, Play with Hanga etc. Nowadays the ideas of modernized practical use on seasonal customs was to connect with modernized scientific technology and designate commemoration day. The items for connecting with modernized scientific technology were new year card, painting and recording sound with traditional seasonal customs, food areas, cake with seven kind of cereals, play areas, hand wrestling, cockfighting in folks and customs areas. Also the items for designating commemoration days were the Suelbeam and Suelbeam Socks present for the aged people, man cooking day, Korean traditional workers day in folk and ceremony areas.

• 한국생활과학회지
• /
• 제13권1호
• /
• pp.17-27
• /
• 2004

The purpose of this study was to examine whether the intergenerational program affected the children's perceptions on the elderly and aging. This study also investigated how the children evaluated the program. The study methods was one group pretest-posttest design. The subjects were 30 elementary school children from 1st to 3rd grade. The intergenerational program was composed of 6 activities: recreation activity for rapport, making a kite, gardening, learning old customs, education of traditional manner, and making rice-cakes. It was executed for two weeks. Data for children's perceptions on the elderly and aging were collected by the interview using questionnaire at pretest-posttest. The results of the qualitative data analysis showed that the children's perception on the elderly and aging changed more positively after the program. There were significant differences between pre- and post-test on the children's perceptions of aging and intellectual aspects of the elderly. Most of the children evaluated the program very positively.

• Ocean and Polar Research
• /
• 제42권1호
• /
• pp.77-88
• /
• 2020

This paper presents the coordinate systems used for trawl doors modeling, and provides matrix equations of connection between these systems. The projections of the forces acting on the door into axes of various coordinate systems were obtained, which were used in the door equilibrium equations. Six equilibrium conditions for the door as a solid were obtained: formulas that allow for the door area in plan to be determined; its weight in water; its mass; three moment equations for determining the position of the warp and backstrops fastening points to the door with triangular and quadrangular backstrop arrangements. It was found that the moment equilibrium equations of trawl doors are generally incompatible, which was not found by any of the authors who have previously conducted research into trawl doors. Using the Kronecker-Capelli theorem, the compatibility equation is obtained. This equation includes the coordinates of the backstrop fastening points to the door, which means that these points cannot be randomly selected. The technique of determining the warp and backstrops' fastening points position to the door is described. Conditions of directional (by angle of attack) and roll (in angle of roll) stability of the doors' equilibrium are presented. The equations presented in this paper comprise a mathematical model that allows, when designing the doors, to select optimal parameters, as well as to carry out adjustments for trawling purposes to ensure the stable movement of the doors and the entire trawl system.

• 대한조선학회논문집
• /
• 제59권6호
• /
• pp.439-446
• /
• 2022

Efforts to reduce carbon dioxide(CO₂) emissions are being carried out due to climate environmental problems. Eco-friendly ships are also being developed, and various energy saving measures have been developed and applied. In ships, researches have been conducted in various fields such as electric propulsion system and energy saving devices. In addition, the development of ships using various renewable energy, such as kite using wind power and wind power generation, has been carried out. This paper proposes a plan to use renewable energy for ships by applying wave generators to small ships. In 2016, 130 small domestic ships drifted by sea due to discharge of starting storage batteries, and discharge cases accounted for the largest portion of the causes of domestic ship accidents. This is due to the excessive use of storage batteries for starting the main engine by departing in a weak storage battery state for small ships. Accordingly, two type wave power generators - opened flow wave power generator and enclosed vibrator type wave power generator - are developed for charging a starting storage battery when the ships are stationary at sea or port. Opened flow wave power generator utilizes the flow of fluid in the ship by using wave induced ship motion. Enclosed vibrator type wave power generator utilizes the pendulum kinetic energy located in a ship due to wave induced ship motion.

• 한국어류학회지
• /
• 제34권2호
• /
• pp.119-126
• /
• 2022

본 연구는 동중국해에서 수집한 치어(체장 5.2 mm)의 종을 COI 바코딩을 통해 남방표문쥐치(Naso hexacanthus)로 동정하고, 형태를 처음으로 보고한다. 치어는 마름모꼴의 몸통으로 등지느러미와 뒷지느러미의 첫 극조는 길고 톱니가 나 있었다. 뒷지느러미 기저부에 네 개의 흑색소포, 미병부에 밀집한 흑색소포, 뇌 표면에 퍼져 있는 흑색소포가 있었다. 작은 가시 한 개가 각각 콧등과 눈 뒤에 있었고, 톱니 모양의 돌기가 머리, 눈 위, 전새개골 내부와 외부, 새개골 아래와 옆 부분에 발달하였다. COI 바코딩으로 동정한 남방표문쥐치 치어의 형태적 특징은 치어의 종 동정에 유용할 것이다.