• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2753-2755
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• 2005

최근 들어 공장에서만 사용되는 로봇을 탈피하여, 사람과 함께 생활하면서 서비스를 제공할 수 있는 인간 친화적인 로봇이 전 세계적으로 개발되고 있다. 인간과 자연스런 상호작용을 위하여, 화자를 바라보고, 깨끗한 음성신호를 얻는 과정에서 음원의 위치 추적은 필연적이다. 본 연구는 마이크로폰에 도달되는 동일 신호의 도착시간지연(Time Delay of Arrival)정보를 이용하여, 음원 위치를 구하는 기존의 수학적인 방법론[1]을 소개하고 검토한다. 모의실험을 통하여, 방법론[1]이 허상음원을 생성하는 음원 위치 측정임을 보인다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.826-828
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• 2015

In this paper, Propose an efficient method that can operate at fixed stations Beam-Steering. Typical Beam-Forming techniques are performed using a delay time between the signal reaching each antenna array. The Beam-Forming method requires a lot of complexity and cost. This paper suggest a Beam-Steering method using a signal-to-noise ratio and a received signal strength. Analyzes the algorithm about proposed method.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1795-1796
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• 2008

과학기술의 발전과 함께 인간형 서비스 로봇에 대한 관심이 고조되고 있다. 서비스 로봇의 핵심 중의 하나는 인간과의 상호작용이라 할 수 있다. 자연스러운 상호작용을 위하여, 화자를 바라보고, 깨끗한 음성신호를 얻는 과정에서 음원의 위치 측정은 필연적이다. 본 논문은 마이크로폰에 도달되는 동일 신호의 도착시간지연(Time Delay of Arrival: TDOA) 특성 행렬을 정의하고, 이를 이용하여 공간상의 화자 위치 측정 방법론을 제안하였다. 휴머노이드 로봇의 머리에 마이크로폰 배열을 구성하였고, 실제 시스템을 통한 실험을 통하여 방향 검지 및 높이 구분을 실행하였다.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.431-432
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• 2017

본 논문은 자유 피스톤 엔진에 적용되는 단상 선형발전기용 전력제어시스템에 관한 연구이다. 자유 피스톤 엔진 선형발전시스템은 피스톤의 움직임을 구속하는 기구가 없기 때문에 기계적 마찰 손실이 적고 상사점 도달 시간이 짧아 에너지 효율측면에서 기존의 피스톤 엔진보다 유리한 기술이다. 하지만, 자유 피스톤 엔진의 경우 초기 기동 할 수 있는 동력원이 필요하며, 단상 선형 발전기의 경우 짧은 스트로크 및 낮은 속도로 인해 인덕턴스가 크게 설계 되어, 높은 인덕턴스로 인한 전류의 위상 지연으로 역률이 낮아지게 되고, 응답성이 떨어지는 문제점을 가지고 있다. 이러한 문제점을 해결하기 위해 본 논문에서는 역률 보상 및 응답성을 높일 수 있는 자유피스톤 엔진용 단상선형발진기용 전력제어시스템을 제안한다.

• The Journal of the Acoustical Society of Korea
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• v.35 no.6
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• pp.411-418
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• 2016

In this paper, we developed a new method estimating the location of ballistic missile launching using infrasound signals. Infrasound signal generated from the North Korea's ballistic missile launch was used as source data and its signal was recorded at KMA (Korea Meteorological Administration) infrasound stations located at Cheorwon and Yanggu. Time-frequency analysis, TDOA (Time Delay of Arrival) method and spherical trigonometry were applied for data processing of signal recorded and occurrence location detection. We could confirm the outstanding performance of the algorithm estimating source location which was only 3 km apart from the actual launching site.

• Journal of Soil and Groundwater Environment
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• v.13 no.6
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• pp.85-92
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• 2008

Water in Soyang River is an essential source for citizens of Chuncheon and Seoul areas. In 2006, turbid water in Soyang River aggravated by the typhoon Ewiniar, sustained for over 280 days unlike conventional years, then which interrupted water supply of Chuncheon and Seoul areas. Soil erosion derived from high cool lands constituting about 55% of Soyang River area is considered one of main causes for the turbid water, including imprudent development of mountainous area, road expansion, and road construction for forestry. According to analysis of turbidity, precipitation and reservoir level in Soyang River region for June 2006${\sim}$August 2008, the turbidity showed a peak correlation (r = 0.28) at a lag time of 49 days and especially did an excellent correlation (r = 0.60) with the reservoir level at a lag of 4 days. In the meantime, a critical turbidity of 31 NTU at Soyanggang Dam was estimated, over which would cause turbid water at Paldang Dam. In addition, a master recession curve was suggested, from which sustaining time of turbid water can be predicted.

• The KIPS Transactions:PartC
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• v.11C no.3
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• pp.353-360
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• 2004

In this Paper, We propose an efficient iteration decoding control method with variable iteration decoding of iteration codes decoding using Cyclic Redundancy Check. As the number of iterations increases, the bit error rate and frame error rate of the decoder decrease and the incremental improvement gradually diminishes. However, when the iteration decoding number is increased, it require much delay and amount of processing time for decoding. Also, It can be observed the error nor that the performance cannot be improved even though increasing of the number of iterations and SNR. So, Suitable number of iterations for stopping criterion is required. we propose variable iteration control method to adapt variation of channel using Frame Error-Check indicator. Therefore, the amount of computation and the number of iterations required for iteration decoding with CRC method can be reduced without sacrificing performance.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.1 s.28
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• pp.29-37
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• 2007

The effect of meteorological factors such as air temperature (AT), wind speed (WS), precipitation (Pre) on the variation of water temperature (WT) and salinity (Sal) in the West Sea of Korea for the period 1971 to 2001 was illustrated. As a result of this study, WT-AT, WT-Pre, and Sal-WS had positive correlation, reversely WT-WS, Sal-AT and Sal- Pre had negative correlation. In the surface layer, time lag between atmospheric factors and oceanographic factors was 0 to 4 months, on the other hand in the bottom layer, it was delayed 0 to 4 months compared to the surface. WT was affected by AT in the same year, but Sal was affected by precipitation in the previous year. The variation of WT and Sal was in harmony with change of wind speed.

• Journal of the Korean Society of Radiology
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• v.17 no.1
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• pp.53-62
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• 2023

The purpose of this study is to find an optimized imaging technique and evaluate its usefulness by comparing and analyzing the difference in contrast enhancement of lower extremity artery according to the patient's heart rate during lower extremity Computed Tomography Angiography examination. From January 2022 to August 22nd, 139 outpatients who visited Ajou University Hospital and underwent lower extremity angio CT examination were targeted. According to the heart rate, the groups were divided into four groups: A(HR ≤65), B(65 < HR < 80), C(80≤ HR). In addition, among patients with a heart rate of 65 or less, the heart rate was considered, and the scan was divided into D, E, F group with a delay time. The time of arrival of contrast medium and the average value of contrast enhancement were compared and analyzed. As a result of quantitative evaluation, B and C groups with a heart rate of more than 65 times had better HU values in the popliteal artery than A group (HR ≤ 65), and D group showed better HU improvement effects compared to A group (p<0.001). The comparative analysis with other groups was insignificant. The difference in heart rate affected the angiographic intensity of the lower extremities artery. Therefore, it is effective to apply the appropriate test timing for each patient by using the heart rate during the lower extremity angio CT Scan.

• Journal of Korean Orthopaedic Sports Medicine
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• v.1 no.2
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• pp.118-123
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• 2002

Purpose: To report modified technique of inside-out suture in repair of tear of postero medial corner of medial meniscus. Operative technique: Arthroscope is placed through anterolateral portal. Suture hook is delivered through anteromedial portal. By rotating the suture hook, it penetrates the inner portion of the torn meniscus from femoral surface to tibial surface of the meniscus for vertically oriented suture. A PDS suture is delivered through the lumen of suture hook, and the suture hook is withdrawn. The both ends of the suture are retrieved through anteromedial portal by a retriever, either grasper or crochet hook.A Zone-specific cannula is positioned below the inferior surface of the meniscus through anterolateral portal. The Looped Needle designed by the authors is delivered through the lumen of the Zone-specific cannula. The suture end of the tibial surface is placed in the loop of the Looped Needle and pulled out to the surface of posteromedial joint line. The suture end of the femoral surface is pulled out in same manner. A transverse skin incision of 1cm size is made adjacent to pulled out suture and the suture is tied. Discussion: Even though modified inside-out suture technique requires longer operation time than conventional inside-out technique, it provides vertically oriented suture and good tissue coaptation. The authors recommend this modified inside-out suture technique to be good alternative in repairing tear of the posteromedial corner of medial meniscus.