• 펄프종이기술
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• 제37권2호
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• pp.47-56
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• 2005

In technology of ink-jet coating, Image quality from correlation between paper and ink depends on the properties of printer and ink as well as those of paper material. Generally, According to the quality of ink that consists of colorants from 5 to 20 percent, It seems that absorption behavior of each ink is different. In this study, we studied to estimate the effects of dye and pigment ink on the absorption and printing properties using 2-type papers on the market and 3-type silica-based coated papers whose pore structure is different. Using the theory of contact angle to evaluate the absorption property, it was possible to measure the baseline length between paper and ink, volume of droplet as well as contact angle. Also, It was possible to calculate wetting energy(mN/m) and spreading coefficient(mN/m) using the surface tension of each ink. These measurements were available to estimate ink-jet qualities.

• Ocean and Polar Research
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• 제31권3호
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• pp.277-282
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• 2009

Saunders' gulls (Laurs saundersi) which are listed as globally vulnerable species on the IUCN Red List are distributed in East Asia and breed mainly in China and Korea. Their population is estimated to be between 7,100 to 9,600. Songdo reclaimed lands in the western coast of South Korea are the main breeding sites for these species. However, most of these breeding sites have been seriously disturbed in the last several years because of new urban development constructions. This study was conducted to provide baseline data on the breeding ecology of Saunders' gulls. Since 1998, the breeding population has rapidly increased in South Korea, with the number of nests rising from 85 nests in 2000 to 185 nests in 2005. Egg volume is more variable than breadth or length. Clutch size, hatching and breeding success were $2.9{\pm}0.81$ (n=182, mean$\pm$sd.), 48.07% (75 hatched egg/156 eggs) and 29.08% (155 fledglings/533 eggs), respectively. Factors affecting breeding failure were predation, rainfall, starvation and supernormal clutches. These results are provided along with other cited literature to argue for conservation of Saunders' gulls.

• 대한의용생체공학회:의공학회지
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• 제17권2호
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• pp.235-240
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• 1996

The automated ECG diagnostic systems that are odd in hospitals have low performance of P-wave detection when faced with some diseases such as conduction block. So, the purpose of this study was the improvement of detection performance in conduction block which is low in P-wave detection. The first procedure was removal of baseline drift by subtracting the median filtered signal of 0.4 second length from the original signal. Then the algorithm detected R peak and T end point and cancelled the QRS-T complex to get'p prototypes'. Next step was magnification of P prototypes with dispersion and detection of'p candidates'in the magnified signal, and then extraction of contextual information concerned with P-waves. For the last procedure, the CIR was applied to P candidates to confirm P-waves. The rule base consisted of three rules that discriminate and confirm P-waves. This algorithm was evaluated using 500 patient's raw data P-wave detection perFormance was in- creased 6.8% compared with the QRS-T complex cancellation method without application of the rule base.

• 한국항공우주학회지
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• 제37권9호
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• pp.829-836
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• 2009

말굽와류로 대표되는 3차원 유동현상은 필연적으로 주유동에 대한 2차 유동의 형태로 발생되며, 유동손실을 유발하게 된다. 본 논문에서는 2차유동 손실을 일으키는 주요 요인중의 하나인 말굽와류의 강도를 감쇄시키기 위해 일반적인 날개 앞전에 설치한 판에 대해, 판의 설치 높이, 길이, 폭 및 두께 등의 형상변수를 설계변수로 정하여 이를 최적화하였다. 근사최적설계 기법을 이용 최적화를 수행하였으며, $FLUENT^{TM}$와 $iSIGHT^{TM}$를 이용하였다. 최적화 수행결과, 기준 모델의 경우보다 전압력 계수가 약 7.5% 감소하였다.

• 한국항공우주학회지
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• 제34권1호
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• pp.89-94
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• 2006

DGPS는 GPS위성배열의 기하학적인 특성에 따라 수평면 정확도에 비해 고도 정확도가 좋지 않다. DGPS고도를 보정하기위해 두 개의 기압고도계를 사용하였고 각각 이동국과 기준국에 설치하여 차분된 고도를 얻어냈다. 이 차분된 고도는 DGPS 고도측정치와 칼만필터로 결합하여 향상된 고도를 추정한다. 이와 같은 차분된 고도는 기존의 상대고도에 기반을 두고 있지만 압력 고도가 아닌 절대고도를 주는 것에 차이가 있다. 또한 기저선의 변화에 따라 차분된 고도가 얼마나 정확성을 갖고 있는지 실제 실험을 통해 확인한다.

• 한국측량학회지
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• 제30권6_2호
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• pp.673-680
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• 2012

Long-term GPS data analysis was performed in order to analyze the seasonal variation of tropospheric delay and the success rate of the ambiguity resolution. For this analysis, a total of 57 stations including 10 IGS stations in East Asia were processed together with double-differenced observables using Bernese GPS Software V5.0. The time span for this study ranges from 2002.0 to 2012.5 (10.5 years). The average baseline length is 339.0 km and the maximum reaches up to 2,000 km. The analysis is focused on two things: the annual variation of the tropospheric delay and the ambiguity resolution rate. The tropospheric delay is closely related to the weather condition, especially relative humidity, therefore it was estimated that the maximum would be in summer, while reaching its minimum in winter with the apparent seasonal variations. On the contrary, however, the success rate of the ambiguity resolution shows the opposite pattern: its maximum was in winter and minimum in summer. The fact seems to be induced by the surrounding conditions; that is, the trees thick with leaves near the GPS antenna interfere with GPS signals in summer. This seems to confirm partly that there is a distinct trend in the decreasing success rate since 2006 because the trees are growing every year. It is necessary to eliminate the factors that degrade the GPS quality and the tropospheric modeling for Korea needs to be studied further.

• 한국항공우주학회지
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• 제43권11호
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• pp.952-962
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• 2015

효율적인 추진기관 개발을 위해 여러 종류의 고도 보정 노즐에 대한 연구가 진행되고 있다. 본 논문에서는 향후 듀얼 벨 노즐 연구를 위한 기초자료로서의 활용을 위해 독일 DLR에서 수행한 연구내용을 바탕으로 듀얼 벨 노즐의 주요 특성을 조사하고 핵심 변수를 도출하였다. DLR은 다양한 실험을 통해 변곡각과 천이 NPR은 비례한다는 것과 확장부 길이와 측하중은 비례하지만 천이 NPR과 천이 지속시간과는 반비례한다는 것을 밝혔다. 성능 예측 과정을 통해 노즐의 형상이 결정될 수 있고 요구 성능에 맞게 변수간의 최적화가 필요하다.

• 디지털융복합연구
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• 제14권1호
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• pp.195-201
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• 2016

본 논문에서는 진폭-위상 복합비교 방향탐지 방식과 상관형 위상비교 방향탐지 방식의 방향탐지 정확도에 대해서 기술하였다. 복합비교 방식은 지향성 빔 특성을 갖는 스파이럴 안테나를 사용하고 상관형 방식은 블레이드 안테나를 사용하여 방위각 $360^{\circ}$를 동시에 탐지할 수 있는 균일원형배열(UCA: uniform circular array) 구조로 안테나를 배치하고 방위각의 방향탐지 정확도를 분석하였다. 3개의 안테나를 배치하는 경우 신호잡음비(SNR)가 20dB이고 파장에 대한 안테나 사이의 거리($D/{\lambda}$)가 0.5인 경우 복합비교 방식은 방향탐지 정확도가 $4.0^{\circ}$, 상관형 위상비교 방식은 방향탐지 정확도가 $1.8^{\circ}$로 나타나서 상관형 위상비교 방식이 정확도가 높은 것을 확인하였다.

• 한국통신학회논문지
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• 제21권10호
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• pp.2563-2578
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• 1996

In this paper, channel error characteristics are investigated to alleviate the channel error propagation problem of the digital TV transmission systems. First, error propagation problems, which are mainly caused by the inter-frame dependancy and variable length coding of the MPEG-2 baseline encoder, are intensively analyzed. Next, existing channel resilient schemes are systematically classified into two kinds of schemes; one for the encoder and the other for the decoder. By comparing the performance and implementation cost, the encoder side schemes, such as error localization, layered coding, error resilience bit stream generation techniques, are described in this paper. Also, in an effort to consider the parcticality of the real transmission situation, an efficient error detection scheme for a decoder system is proposed by employing a priori information of the bit stream syntas, checking the encoding conditions at the encoder stage, and exploiting the statistics of the image itself. Finally, subsequent error concealment technique based on the DCT coefficient recovery algorithm is adopted to evaluate the performance of the proposed error resilience technique. The computer simulation results show that the quality of the received image is significantly improved when the bit error rate is as high as 10$^{-5}$ .

• 제어로봇시스템학회논문지
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• 제3권6호
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• pp.602-612
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• 1997

With GPS carrier phase measurements from more than two antenna which attached to the vehicle, precise attitude can be easily obtained if the integer ambiguity included in carrier phase measurement is resolved. Recently some special products which use dual frequencies or has one receiver engine with multiple antenna are announced. But there are still strong requirements for the conventional single frequency off-the-shelf receiver. To meet these requirements, an efficient integer ambiguity resolution technique is indispensable. In this paper, a new technique to resolve integer imbiguity with single frequency receivers is proposed. The proposed method utilize the known baseline length as a constraint of independent elements of integer ambiguities. With this constraints, the size of search volume can be greatly reduced. Thus the true integer ambiguity can be easily determined with less computational burden and number of measurements. The proposed method is applied to real data to show its effectiveness.