• Proceedings of the Korean Information Science Society Conference
• /
• 2008.06d
• /
• pp.406-411
• /
• 2008

무선 MAC 을 위한 802.11은 유니캐스팅 통신을 할 때 ACK를 이용하여 자체적인 신뢰성을 부여한다. 그러나 오류율이 낮거나 패킷 크기가 작은 환경에서 TCP와 같이 상위 계층의 신뢰성 보장 기능이 있는 경우 MAC 계층에서 모든 패킷에 대해 ACK를 이용하는 것은 오버헤드가 될 수 있다. 본 논문에서는 ACK 응답을 하지 않는 멀티캐스팅을 통해 유니캐스팅 통신 을 구현하는 802.11 ACK-less 유니캐스팅 기법을 제안하고 기존의 ACK 기반의 802.11 유니캐스팅과 통신 성능 및 에너지 측면에서 비교 실험하였다. 실험결과 에러율이 낮고, 패킷의 크기가 작고, LAN 통신 환경에서 처리율과 에너지 측면에서 우수한 성능을 보인다. 반면 무선 통신 환경이 열악한 경우에 에너지 효율은 유지하더라도 처리율은 뒤떨어지는 현상이 나타났다. 이를 보완하기 위해 선택적 ACK-less 유니캐스트 기법을 제안한다.

• Journal of the Speleological Society of Korea
• /
• no.85
• /
• pp.1-14
• /
• 2008

Electroluminescent Display(ELD) will be the innovative ideas to replace existed electricity illumination systems that consider to under effectiveness and environmental pollution generators in the commercial caves because ELD has less heat and low electricity consumption by the new illumination materials. Characteristics of the ELD are as following: it is a proper matter for the small merchandise ads due to its thickness is only below 3oo micoron, electricity consumption of ELD is less (1/3) than LED, ELD that is a whole face illumination system is much brighter than LED that is a dot illumination system, ELD is longer life than others due to its less light generation systems, ELD is any problems to bend, and it is a best device to use a light board ads. ELD has advantages on conservation of cave biosystems and reduce pollution when ELD is installed in touring spots and emergency corridors of weak illuminated cave internal areas by less heating and low electricity consumption using the indirect illumination of the ELD. Therefore when the high technologic ELD is installed in the commercial caves in Korea, it will be innovating cave environmental systems, saving budgets, and increasing tours.

• The Journal of Fisheries Business Administration
• /
• v.48 no.4
• /
• pp.11-25
• /
• 2017

The purpose of the study is to analyze the status and trend of less favored condition of fishing village in Korean island regions using the census of agriculture, forestry and fisheries. The less favored condition was measured as the difference in accessibility to major services and in fishery sales and resident infrastructure, applying the difference-in-difference method and propensity score matching method respectively. The result shows that access to major services has improved in island area between 2010 and 2015, implying that related policies such as the island comprehensive development project have been successful to some extent. However, some educational facilities, cultural facilities, and health facilities still have low inaccessibility and fishery sales are also significantly lower than in general area. This suggests that it is necessary to maintain related policies like the direct payment of fisheries.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.17 no.1
• /
• pp.156-161
• /
• 2017

This work presents a novel structure for junction-less tunneling field effect transistor (JL-TFET) with a floating gate over the source region. Introduction of floating gate instead of fixed metal gate removes the limitation of fabrication process suitability. The proposed device is based on a heavily n-type-doped Si-channel junction-less field effect transistor (JLFET). A floating gate over source region and a control-gate with optimized metal work-function over channel region is used to make device work like a tunnel field effect transistor (TFET). The proposed device has exhibited excellent ID-VGS characteristics, ION/IOFF ratio, a point subthreshold slope (SS), and average SS for optimized device parameters. Electron charge stored in floating gate, isolation oxide layer and body doping concentration are optimized. The proposed JL-TFET can be a promising candidate for switching performances.

• International Journal of Human Ecology
• /
• v.5 no.2
• /
• pp.93-110
• /
• 2004

The purpose of this study is to investigate the money management behavior according to the consumption value for consumers, especially for adolescents. Using 502 samples of middle school adolescents, a survey was conducted from May 10 to May 20, 2004. The main results were as follows: 1) The consumption value for adolescent consumers was categorized conspicuous-consumption value, brand-oriented value, mental-oriented value and advertising-dependent value. 2) Female adolescent, with more private spending money, with mobile phone, with importance on brand when purchasing mobile phone, paying more for using mobile phone, having conspicuous-consumption value, with more importance for brand when purchasing mobile phone and having more advertising-oriented value. Adolescent consumers with less private spending money, less payment for mobile phone and having mental-oriented value. 3) Female, with more educated mother, with less spending private money and having better money management behavior. 4) With less conspicuous-consumption value, more mental-oriented value, adolescent consumers have better for money management behavior.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.17 no.6
• /
• pp.539-545
• /
• 2012

Due to merits cost and efficiency, the transformer-less type photovoltaic (PV) inverters have been popularized in the solar market. However, the leakage current flowing through a parasitic capacitor between PV array and ground can cause adverse effect in the transformer-less PV system. In this paper, a bi-directional PV inverter with high efficiency and low noise is proposed for the PV system with an energy storage device. The proposed inverter is a transformer-less type and performs the bi-directional power control between dc sources and grid with high efficiency. In addition, the proposed inverter can suppress the leakage current and obtain low noise characteristic. Finally, 3-kW prototype was implemented to confirm validity of the proposed inverter.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.1
• /
• pp.41.2-41.2
• /
• 2012

It has been suggested that merging plays an important role in the formation and the evolution of early-type galaxies (ETGs). Optical-NIR color gradients of ETGs in high density environments are found to be less steep than those of ETGs in low density environments, hinting frequent merger activities in ETGs in high density environments. In order to examine if the flat color gradients are the result of dry mergers, we studied the relations between merging features, luminosities, environments and color gradients of 196 low redshift ETGs selected from Sloan Digital Sky Survey (SDSS) Stripe82. Near Infrared (NIR) images are taken from UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS). Color (r-K) gradients of ETGs with tidal features are a little flatter than relaxed ETGs, but not significant. We found that massive (> 10^11.3 solar masses) ETGs have -40% less scattered color gradients than less massive ETGs. The less scattered color gradients of massive ETGs could be evidence of dry merger processes in the evolution of massive ETGs. We found no relation between color gradients of ETGs and their environments.

• Journal of the Speleological Society of Korea
• /
• no.70
• /
• pp.55-62
• /
• 2006

The Wooro cave speleothem displays comparatively very less developed characteristics due to its unactive fluviation, less soluable carbonate rocks, 3nd disconnected short voids. The Weoro cave consists of stalactite, stalagmite, flowstone, rimstone, and moonmilk, however, it is not exhibite soda straw, cave pearl, pisolites, curtain, drapery, cave flower, anthodite, cave coral, helictite. heligmite, boxwork, pendent and, cemented shield. The main cause of the underdevelopment speleothem of the Wooro cave probably less peneturated waters or less calcite compostion of the carbonate rocks.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.34D no.7
• /
• pp.79-87
• /
• 1997

Untill now, the most well-known cofiguration for waveguide grating router(WGR) is composed of radiative star couplers and arrayed waveguide grating(AWG), which usually suffer form the rdiation loss of around 3dB or more. Therefore, te improved design of WGRs is needed to reduce the loss. In ths paper, we propose a novel WGR composed of multimode interference couplers which have good unifiormity, fabrication tolerance, and very low excess loss, and suggest the efficient algorithm to find the proper path length differences of AWG for given channel spacing and channel assignment to each output prot. The simulated spectral responses of the proposed WGR using the finite difference beam propagation method (BPM) show that the excess loss is less than 0.3dB and the crosstalk less than -25dB in case of 4x4 WGR, and the excess loss less than 0.4dB and the crosstalk less than -25dB in case of 8x8 WGR for all the channel wavelengths.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2016.10a
• /
• pp.816-818
• /
• 2016

LPWA 기술은 IoT 환경이 가지는 낮은 전송거리와 배터리 제약을 해결할 수 있는 통신규약이다. LPWA에서 주목 받는 LoRa 기술은 디바이스에서 전송방식을 선택할 수 있는 클래스 A, B, C를 제공한다. 이 논문은 클래스 B 옵션에서 동기는 맞으나 전송 중 Beacon메시지를 분실하였을 경우, 바로 실행되던 Beacon-less동작을 억제하도록 최대 실패 횟수를 설정한다. 기존방법보다 Beacon-less동작이 기존 방법에 비해 30배 이상 적게 동작하여 디바이스의 에너지 소모를 줄였다.