• 전자공학회논문지A
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• 제29A권7호
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• pp.56-63
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• 1992

A measurement technique of the surface generation velocity S$_o$ using the BC(buried channel) MOS structure with shallow and low doped channel layer (BC MOS S$_o$ measurement technique) is presented and verified analytically and experimentally. Using this measurement technique, S$_o$ can be measured more accurately than that measured using the gate-controlled diode SS1oT measurement technique. When S$_o$ is measured for the two techniques from a BC MOS structure test patten with gate length of 171$\mu$m, the results are 0,66cm/sec and 0.28cm/sec for the former and the latter respectively.

• 한국전자통신학회논문지
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• 제10권2호
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• pp.219-226
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• 2015

대표적인 4세대 이동통신 시스템으로서 LTE는 과거 이동통신 시스템에 비하여 훨씬 더 높은 전송 속도를 제공한다. 그러나 무선 환경의 특성 상 LTE가 제공하는 전송 속도는 무선 채널의 상태에 따라서 큰 영향을 받을 수 있다. LTE 시스템의 무선 접속을 통해서 제공되는 대부분의 서비스에 대한 사용자의 만족도는 전송속도에 일차적인 영향을 받게 된다. 따라서 본 논문에서는 무선 채널의 상태를 대표하는 다양한 품질 지표를 선정하고 이들에 대한 실체 측정을 실시하여 각 품질 지표의 변화에 대한 LTE 시스템의 전송 속도의 변화를 관찰하였다. 그 결과 채널의 상태가 나빠질수록 신호의 세기가 아닌 신호의 품질이 LTE 시스템이 제공하는 전송 속도에 밀접한 영향을 미친다는 사실을 알 수 있었다.

• Ecology and Resilient Infrastructure
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• 제4권2호
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• pp.97-104
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• 2017

우리나라의 하천은 대부분 치수를 위한 제방공사를 통해 직강화되어 있다. 하천과 홍수터의 횡적 연결성을 회복하기 위해서는 제방에 의해 격리된 옛홍수터를 탐색하고 현재 토지이용현황을 파악하는 것이 중요하다. 본 연구의 목적은 청미천에서 옛홍수터를 탐색하고 토지이용현황을 분석하는 것이다. 옛홍수터는 지리정보시스템을 이용하여 청미천 유역에서 수치표고모델, 연속수치지도 및 계획홍수위를 중첩하여 산출하였다. 탐색된 옛홍수터의 토지이용현황은 토지피복도를 이용하여 분류하였다. 청미천에서 격리된 옛홍수터는 총 104 지점이 탐색되었으며, 전체면적은 11.9 km2이었다. 옛홍수터의 토지이용은 농경지가 87.1%로 대부분을 차지하였다. 청미천의 하류에는 산지로 둘러싸인 소규모 패치 형태의 옛홍수터가 많았으며, 이러한 지역은 시가화지역의 비율이 낮고, 농경지의 비율이 높아 하천 횡적 연결성 복원의 효율이 높을 것이다. 청미천에서 탐색된 격리된 옛홍수터와 토지이용 현황은 향후 하천 복원계획에 기초자료로 이용될 수 있을 것이다.

• 한국통신학회논문지
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• 제27권3B호
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• pp.226-236
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• 2002

본 연구에서는 12.2 Kbps, 64 Kbps, 384 Kbps 트래픽 등의 다양한 QoS를 요구하는 서비스에 대하여 IMT-2000 비동기 방식 시스템의 제어국 (Radio Network Controller; RNC)내의 셀렉터의 트래픽 채널 자원을 효율적으로 이용하기 위한 채널 자원 블럭의 할당 및 자원 관리 방식을 제안하고, 그 성능을 평가한다. 먼저, 트래픽 채널 블럭을 효율적으로 이용하기 위한 방법으로 채널 자원 블럭중에서 일부는 각 트래픽 형태가 전용으로 사용하고 일부는 여러 트래픽 형태가 공유하여 사용하는 방식의 두 가지가 혼합된 하이브리드 방식을 제안하구 모든 트래픽 형태가 공유하여 사용하는 경우와의 블럭킹 확률을 비교하여 제안한 자원 블럭 할당 방식의 성능이 우수함을 보인다. 또한, 채널 자원 블럭 및 블럭내의 트래픽 채널 자원을 효율적으로 할당, 해제, 관리하기 위한 방안으로 블럭을 선택하는 블럭관리 단계와 선택된 블럭내의 사용 가능한 채널을 선택하는 태스크관리 단계의 블럭앤태스크 관리 방식을 제안하고, 하나의 자원 블럭내에서의 음성 트래픽의 호 요구시에 할당할 트래픽 채널을 찾는데 소요되는 평균 탐색 횟수를 평가한다.

• 전자공학회논문지A
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• 제32A권9호
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• pp.1177-1183
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• 1995

This paper proposes a new modulation scheme of $\pi$/4-DQPSK with stepped phase for a frequency selective fading channel. In the proposed modulation scheme, the phase of transmitted signal is shifted in the mid of a symbol duration in order to reduce the effect of multipath delay spread. It reduces the irreducible error of $\pi$/4-DQPSK over a frequency selective fading channel. It is shown that $\pi$/4-DQPSK with stepped phase achieves smaller average bit error probability than regular $\pi$/4- DQPSK by simulation. The former achieves much smaller average bit error probability than the latter for small TEX>${\tau}/T_{s}$.

• Journal of the korean society of oceanography
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• 제34권3호
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• pp.133-143
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• 1999

We carried out simultaneous and long-time observations of currents across the western channel of the Korea Strait during the period of May, 1994 to September, 1996 in order to understand the spatial and temporal variability of tidal and nontidal currents in the Strait. Results show that currents in the Strait are quite variable in space and time, and they largely consist of mean current and diurnal and semidiurnal tidal currents of about equal magnitudes. The mean currents include the Tsushima Current and the Korea Strait Undercurrent at the center of the channel. The former occupies the upper two-thirds and the latter the lower one-third of the water column. The semidiurnal and diurnal currents are largely rectilinear in the direction of NE-SW and their amplitude variation across the channel appears to be small. However, the diurnal currents at some locations show rotational characteristics with significant nontidal effects. The station close to the Korean coast leads the phase and the phase difference of the semidiurnal current across the channel appears to be less than half an hour while that of the diurnal current is over five hours.

• 혜화의학회지
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• 제17권1호
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• pp.137-143
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• 2008

We have conclusions after the study of muscular system about large intestine channel of hand yangmyung muscle. 1. Judging from many studies of interrelation between Meridian muscle and muscle. it is considered that Meridian muscle theory has some similarities with modern anatomical muscular system. 2. There is a wide defference betwean myofacial pain syndrome and meridian muscle theory in that the former explains each muscle individually, while the latter classifies muscles systematically in the view of organism. 3. It is considered that large intestine channel of hand yangmyung muscle contains extensor digitorum muscle, extensor muscle of index finger, brachioradialis muscle, triceps brachii muscle, Rhomboid major muscle, trapezius muscle, sternocleidomastoid muscle and muscle levator labii. 4. The symptoms of large intestine channel of hand yangmyung muscle is similar to referred pain of modern Myofacial pain syndrome, and the medical treatment of "I-Tong-Wi-Su" is similar to that of Myofacial pain syndrome.

• 센서학회지
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• 제26권6호
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• pp.408-413
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• 2017

In this paper, we newly developed a byte-inverted transmission method for flicker-free visible light communication (VLC). The VLC transmitter sends original data in the former half period of the clock, and inverted data and in the latter half period of the clock. The VLC receiver receives the original data in the in the former half period of the clock. In this system, we used 480Hz clock that was generated from the 60Hz power line. The average optical power of the LED array in the transmitter is constant, thus flicker-free, in the observation time longer than the period of the clock that is about 2ms. This period is shorter than the maximum flickering time period (MFTP) of 5ms that is generally considered to be safe. This configuration is very useful in constructing indoor wireless sensor networks using LED light because it is flicker-free and does not require additional transmission channel for clock transmission.

• 한국전산유체공학회지
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• 제13권4호
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• pp.107-113
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• 2008

The present study numerically simulates the flow and heat transfer characteristics of rib-induced secondary flow in a square cooling channel with staggered V-shaped ribs, extruded on both walls. The rib pitch-to-height ratio (p/h) varies from 2.8 to 10 with the rib-height-to-hydraulic diameter ration (h/$D_h$)of 0.07 and the Reynolds number of 50,000. Shear stress transport (SST) turbulence model is used as a turbulence model. Computational results show that complex secondary flow patterns are generated in the channel due to the snaking flow in the streamwise direction for all tested cases. In the range of p/h=5 to 10 the staggered V-shaped rib gives about 3 times higher heat transfer augmentation than the reference smooth pipe with high heat transfer on both front side and the area around the leading edge of the ribs, while the former cases give about 18 times higher streamwise pressure drop than the latter ones. However, for the thermal performances, based on the equal pumping power condition, the case of p/h=2.8 gives the best result among three cases, mainly due to relatively low streamwise pressure drop, although it gives relatively low heat transfer augmentation.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 학술대회
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• pp.125-130
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• 2008

The present study numerically simulates the flow and heat transfer characteristics of rib-induced secondary flow in a cooling channel with staggered V-shaped ribs, extruded on both walls. The rib pitch-to-height ratio (p/h) varies from 2.8 to 10 with the rib-height-to-hydraulic diameter ration ($h/D_h$) of 0.07 and the Reynolds number of 50,000. Shear stress transport (SST) turbulence model is used as a turbulence model. Computational results show that complex secondary flow patterns are generated in the duct due to the snaking flow in the streamwise direction for all tested cases. In the range of p/h=5 to 10 the staggered V-shaped rib gives about 3 times higher heat transfer augmentation than the reference smooth channel with high heat transfer on both front side and the area around the leading edge of the ribs, while the former cases give about 2.5 times higher streamwise pressure drop than the latter ones. Consequently, for the thermal performances, based on the equal pumping power condition, the staggered ones give about 2 times higher values than the latter ones with more uniform heat transfer distribution.