• 한국산학기술학회논문지
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• 제7권3호
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• pp.373-378
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• 2006

현재 RFID 시스템에서 해결해야 할 가장 큰 문제 중 하나는 태그 간의 충돌로 인해 인식 효율이 떨어지는 것이다. 할당받은 라운드 크기에 비해 인식해야 될 태그의 수가 많아지면 충돌이 발생하는 슬롯이 많아지게 된다. 이렇듯 고정적인 라운드크기의 할당은 태그 충돌 발생의 원인이 되며 그러므로 할당받는 라운드 크기는 적절하게 조절되어야 한다. 본 논문에서는 태그 간의 충돌을 줄이고 효율적인 태그 인식을 위해 라운드 크기를 동적으로 할당하는 알고리즘을 제시하였다. 리더는 매 라운드가 끝난 뒤 얻은 슬롯의 충돌 정보를 이용하여 라운드 크기를 동적으로 할당한다. 슬롯의 충돌 정보는 충돌이 발생한 슬롯의 수, 충돌이 발생하지 않고 태그가 제대로 인식된 슬롯의 수, 비어 있는 슬롯의 수이다. 충돌 방지 알고리즘으로 슬롯 방식 알로하 알고리즘을 사용했으며 시뮬레이션을 통해 제안한 알고리즘이 태그 수를 미리 알지 못하는 상황에서 아주 유용하게 사용될 수 있음을 확인하였다.

• Journal of information and communication convergence engineering
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• 제7권3호
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• pp.292-296
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• 2009

The performance of anti-collision algorithm in RFID systems, which are based on FSA algorithm, may be affected by the frame size a query round. In this paper, an anti-collision algorithm with early cancellation of query round is proposed to enhance the performance of EPCglobal Class-1 Gen-2. The Q-algorithm calculates a Q value to determine the next frame size during a query round. In the proposed algorithm, if the new Q value is different from the previous one, the reader transmits a QueryAdjust command to cancel the current query round. The simulation results show that the proposed algorithm can have a stable performance irrespective of the C value of Q-algorithm and the number of tags.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권6호
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• pp.2554-2580
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• 2018

Lenstra-Lenstra-$Lov{\acute{a}}sz$ (LLL) is an effective receiving algorithm for Multiple-Input-Multiple-Output (MIMO) systems, which is believed can achieve full diversity in MIMO detection of fading channels. However, the LLL algorithm features polynomial complexity and shows poor performance in terms of convergence. The reduction of algorithmic complexity and the acceleration of convergence are key problems in optimizing the LLL algorithm. In this paper, a variant of the LLL algorithm, the Hybrid-Fix-and-Round LLL algorithm, which combines both fix and round measurements in the size reduction procedure, is proposed. By utilizing fix operation, the algorithmic procedure is altered and the size reduction procedure is skipped by the hybrid algorithm with significantly higher probability. As a consequence, the simulation results reveal that the Hybrid-Fix-and-Round-LLL algorithm carries a faster rate of convergence compared to the original LLL algorithm, and its algorithmic complexity is at most one order lower than original LLL algorithm in real field. Comparing to other families of LLL algorithm, Hybrid-Fix-and-Round-LLL algorithm can make a better compromise in performance and algorithmic complexity.

• 패션비즈니스
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• 제12권6호
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• pp.81-92
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• 2008

The purpose of this study is to develop the applied brassiere pattern of women which are fitting for 75A. The constructing of this experimental brassiere were lower cup, upper cup, front panel and U-wing as well as a full cup embcing the entire breasts. Basing on the bra model from domestic experiment results, development of an applied design, round side type pattern, has been suggested. Thus, suggesting the round variation design bra, which is an applied design based on the basic model based on the breast volume. Based on the sizes that are in reference to Size Korea (2004) and related previous researches, the basic model that has been experimented with 11.4% polyurethane and 88.6% Nylon as the materials, has been selected as the model of research. This takes 75A, the size of which is set according to the underbust circumference and the breasts circumference, as the basic model. It is an application in terms of design, and there is no change to the cup volume or size because it has been moved only from the cutting line. The applied design changes the right side of the lower cup into an easily-movable form and attaches it to the upper cup, and the lower cup takes the right part of the upper cup to form a cup shape of round variation design. It also changes basic straight form of the wings, and alters them into U-shape.

• Carbon letters
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• 제7권2호
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• pp.114-118
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• 2006

Isotropic pitch-based carbon fiber has been activated by steam diluted in nitrogen in order to characterize the microporosity. Especially, 40 wt% burn-off ACFs were prepared from different conditions to compare the pore structure and size. The ACFs were thinly sliced to investigate the inside pores by TEM and image analyzer. As expected, the adsorption characteristics of these ACFs were quite different from one another because of different pore structure and size. Most pores are not slit-shaped but rather round. Small round micropores become broad and irregular as increasing the activation time and temperature.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.911-914
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• 1997

This Experiment was carried out for bur minimization in drilling. New drill geometries are proposed to minimize the burr formation in drilling operation. Three types of drills are made, champer, round and step drill. The burr formed in first cutting by front cutting edge ca be removed in second cutting by the cutting edges in chamfer, round edge and step. New burrs are formed by second cutting and can be minimized according to the change of drill geometry like, chamfer size and angle, corner radius in round drill and step size and angle in step drill. To measure the burr formed in drilling, laser sensor is used.

• 대한수의학회지
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• 제38권3호
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• pp.488-496
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• 1998

Somatotropes, mammotropes and somatomammotropes of the Korean native goat hypophysis were studied by double immunoelectron microscopy using antisera to growth hormone(GH) and prolactin(PRL), and protein A-gold particles of different sizes. Mammotropes were round or oval in shape, and contained round and electron dense secretory granules. The size of secretory granules was variable from 460nm to 680nm in diameter. Somatotropes were elliptical or triangular in shape and the oval nucei were located eccentrically at the periphery of the cell. Secretory granules of the cell were oval in shape and clearly distinguished from round granules of mammotropes. The size of granules was 320~680nm in diameter, smaller than that of mammotropes. Somatomammotropes contained round or oval secretory granules. The granules had intermediate size between somatotropes and mammotropes. Some of granules contained both GH and PRL, while the others contained only one of them.

• Journal of Biosystems Engineering
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• 제34권4호
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• pp.228-233
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• 2009

In order to cut the round bale easily, a roughage cut-feeder for the round bale was developed in this study. This study consists of two parts. One is development of a cutting mechanism and a performance test reported in the previous paper. This is the second part of the study. For the study, recent trend of traditional cutting system was analyzed. Also, cost of the prototype cut-feeder was analyzed and determine the break-even point of farm size was determined by comparing with traditional method using a traditional cutter. A prototype cut-feeder was investigated with the fact that working performance, fiber length and shape of roughage and feeding quality was good. Operating cost of the prototype cut-feeder decreased rapidly with an increase of farm size. Break-even point in terms of farm size was 36 heads for beef and 28 heads for dairy. Also, costs estimated were 118,000 won/head year and 148,000 won/head year, respectively.

• 한국음향학회지
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• 제19권1호
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• pp.16-24
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• 2000

본 논문에서는 긴 왕복 지연시간(round trip delay)이 시스템 성능의 주요 제한 요소로 작용하는 DS/CDMA 기반의 저궤도 이동 위성 시스템에서 가변 스텝사이즈(step size) 방식을 적용한 폐루프(closed loop) 전력제어방식의 성능분석을 수행하였다. 저궤도 위성 통신 채널은 지상의 이동통신 채널과는 근본적으로 다른 긴 왕복 지연 시간이나 앙각(elevation angle)과 같은 고유의 페이딩 효과를 반영하여야 하므로 ESA(Europe Space Agency)의 실측 된 데이터를 기반으로 하여 저궤도 이동통신 채널모델을 구현하였다. 통상적으로 저궤도 위성 시스템에서 위성을 통한 이동 단말기와 관문국사이의 왕복 지연시간은 10∼20ms이므로, 지상에서 사용되는 폐루프 전력제어의 효과는 극히 제한적이고 미미하므로 긴 왕복시간 이나 앙각에 따른 페이딩을 효과적으로 극복하기 위해서는 가변 스텝사이즈 조절방식을 적용한 적응적인 전력제어 방식이 요구된다. 본 논문에서는 이러한 가변 스텝사이즈 조절 방식을 적용한 폐루프 전력제어 방식의 성능을 평가한 결과, 고정 스텝사이즈를 갖는 기존의 폐루프 전력제어 방식보다 왕복 지연시간과 앙각에 따른 신호 대 간섭비(signal to interference ratio; SIR)의 편차값이 현저히 감소됨을 확인하였다. 특히, 전력제어 명령을 측정하는 구간이 왕복 지연시간의 두 배정도가 가장 최적이라는 결론을 얻었다.

• 수산해양기술연구
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• 제39권3호
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• pp.174-180
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• 2003

서해안의 연안성 어종인 쥐노래미는 백령, 대청 근해에서 주요 어종의 하나로 주로 통발에 의해 어획되고 있다. 쥐노래미 어업이 지속적으로 유지되기 위해서, 소형어를 보호하는 효율적인 어구 사용과 현재 정해져 있는 망목크기가 적정한가를 파악하기 위하여 망목선택성 실험을 하였다. 쥐노래미 통발에 대한 망목선택성을 Kitahara의 방법에서 객관성이 있도록 선택성 곡선을 다항식이나 로지스틱 곡선식을 이용하여 구하고, 쥐노래미의 최소성숙체장에 대한 적정망목크기를 구하였다. 통발의 경우, 선택성 곡선(마스터 곡선)을 구할 때 적용한 다항식은 삼중자망에서와는 달리 어체가 큰 부분에서 보정치가 지나치게 작용하여 선택성 곡선을 신뢰할 수 없었고, 로지스틱 곡선이 보다 합리적이었으며, 그 식은 다음과 같았다. s(R) =(equation omitted) 쥐노래미의 최소성숙체장은 21.4㎝로 알려져 있으며, 이 최소성숙체장에 대해 50% 어획될 확률 (L/sub 50/)이 되는 망목크기는 37.0㎜이었다. 현재 통발의 망목크기 제한은 35㎜로 규정되어 있는데 쥐노래미의 경우에 다소 작으나 큰 차이는 없는 것 같다.