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A Simplified Broadband Output Matching Technique for CMOS stacked Power Amplifiers
KO, Jaeyong,KIM, Kihyun,SONG, Jaehoon,NAM, Sangwook 'Institute of Electronics, Information and Communi 2014 IEICE transactions on electronics Vol.97 No.10
<P>This paper describes the design method of a broadband CMOS stacked power amplifier using harmonic control over wide bandwidths in a 0.11 mu m standard CMOS process. The high-efficiency can be obtained over wide bandwidths by designing a load impedance circuit as purely reactive as possible to the harmonics with broadband fundamental matching, which is based on continuous Class-F mode of operation. Furthermore, the stacked topology overcomes the low breakdown voltage limit of CMOS transistor and increases output impedance. With a 5-V supply and a fixed matching circuitry, the suggested power amplifier (PA) achieves a saturated output power of over 26.7 dBm and a drain efficiency of over 38% from 1.6 GHz to 2.2 GHz. In W-CDMA modulation signal measurements, the PA generates linear power and power added efficiency of over 23.5 dBm and 33% (@ACLR = 33 dBc).</P>
Compact HF Surface Wave Radar Data Generating Simulator for Ship Detection and Tracking
Park, Sangwook,Cho, Chul Jin,Ku, Bonhwa,Lee, SangHo,Ko, Hanseok IEEE 2017 IEEE geoscience and remote sensing letters Vol.14 No.6
<P>Toward a maritime surveillance objective, many ship detection and tracking algorithms have been investigated but are faced with poor performance in practical ocean environments. Compact high-frequency (HF) radar has also faced critical issues due to its long coherent processing interval and varying response from its orthogonal antenna structure. Hence, a simulator based on compact HF radar is proposed in this letter to provide a guideline for effective assessment of ship detection and tracking algorithms while considering these practical issues. To validate the proposed simulator, the simulator generated data has been compared with real data obtained by the compact HF radar sites.</P>
Simulation and Ship Detection Using Surface Radial Current Observing Compact HF Radar
Park, Sangwook,Cho, Chul Jin,Ku, Bonhwa,Lee, SangHo,Ko, Hanseok IEEE 2017 IEEE JOURNAL OF OCEANIC ENGINEERING - Vol.42 No.3
<P>This paper proposes an effective method of improving ship detection performance of a compact high-frequency (HF) radar system which has been primarily optimized for observing surface radial current velocities and bearings. Previously developed ship detection systems have been vulnerable to error sources such as environmental noise and clutter when they are applied in a compact HF radar optimized for observing surface current. In particular, the influences of error are reduced by applying a principle component analysis of the generated range-Doppler maps. A compact radar signal model is first developed by the data acquired from an operating compact HF radar site. The proposed method is then validated by comparing it to the conventional ship detection method in terms of detection and false alarm rates. The experimental results confirm that the proposed method shows superior performance in both simulated and practical environments.</P>
Sangbong Ko,Alexander R. Vaccaro,Sangwook Lee,Jaekun Lee,Hojin Chang 대한정형외과학회 2014 Clinics in Orthopedic Surgery Vol.6 No.4
Background: This study was to evaluate the association of lumbar spine facet joint osteoarthritis (LSFJOA) identified by multi-detector computed tomography (MDCT) with age and low back pain (LBP) in an adult community-based population in Korea. Methods: A sample of 472 participants (age range, 20 to 84 years) who underwent MDCT imaging for abdominal or urological lesions, not for chief complaints of LBP, were included in this study. LSFJOA based on MDCT findings was characterized using four grades of osteoarthritis of the facet joints. The prevalence of LSFJOA according to age group (below 40 years, 40–49 years, 50–59 years, 60–69 years, and above 70 years), gender, and spinal level was analyzed using chi-square tests and the association between LBP and LSFJOA adjusting for age, gender, and spine level was analyzed using multiple binary logistic regression test. Results: Eighty-three study subjects (17.58%) had LSFJOA (grade ≥ 2). The prevalence of LSFJOA was not associated with gender (p = 0.092). The prevalence of LSFJOA increased with age (p = 0.015). The highest prevalence of LSFJOA was observed at L4–5 in men (p = 0.001) and at L5–S1 in women (p = 0.003), and at L5–S1 in the overall population (p = 0.000). LSFJOA was not associated with LBP in men (p = 0.093) but was associated with LBP in women (p = 0.003), especially at L3–4 (p = 0.018) and L5–S1 (p = 0.026). Conclusions: The prevalence of LSFJOA based on the computed tomography imaging was 17.58% in the adult community Korean population. The prevalence of LSFJOA increased with age, and the highest prevalence was noted at L5–S1. LSFJOA was not associated with LBP at any spinal level and age except at L3–4 and L5–S1 in women.
사용자 편의성을 고려한 전력계통 해석 프로그램 개발 연구
고백경(Baekkyeong Ko),송지영(Jiyoung Song),한상욱(Sangwook Han),이재걸(Jaegul Lee),신정훈(Jeonghoon Shin),안용호(Youngho An) 대한전기학회 2016 전기학회논문지 Vol.65 No.1
Power system engineers use power systems solution programs such as PSS/E, DSATool, Power World simulators for power system analysis. In this reason, KEPCO has begun to develop independent power system program, KW-PSS(KEPCO World Power system Solution) since 2002 and KW-PSS ver2.0 development was completed in 2011. However, it did not have much better functions compared with other programs. Therefore, we focused on the development of the practical and specialized functions. Consequently, PAZ(Power system AnalyZer) ver3.0 has been developed and it realized a differentiation than previous version. In other words, previous version focused on the basic function of power system analysis, PAZ ver3.0 has implemented many automated functions for power system operators were driven maximize operational efficiency. The unique feature of the implementation is as follows : Automated check for exceeding the breaker capacity, Scheduled outage automation, Control-file wizard for various voltage stability analysis, Scenario-based multiple transient stability analysis and Auto calculation of transmission line impedance. As shown in these functions, Those functions provide to use power system analysis easily by automation and simplification for power system engineers. We will secure national expertise through PAZ ver3.0. In addition it will be able to gain competitive edge through the steady development in the world market.
송혜원,신영희,Justin Sangwook Ko,곽미숙,김갑수 대한마취통증의학회 2012 Korean Journal of Anesthesiology Vol.62 No.1
Porphyrias are a group of diseases characterized by an enzyme deficiency in the heme biosynthesis pathway,resulting in accumulation of precursor molecules in the tissue. Some porphyric patients develop progressive liver disease that requires liver transplantation. This case report describes special anesthetic challenges, including careful selection of drugs and the use of special filters that can exclude harmful wavelengths of ultraviolet, in a patient with porphyria who underwent living donor liver transplantation. Understanding the patient’s status and disease process,and avoiding triggering factors of porphyria attacks, are important for successful liver transplantation anesthesia in patients with porphyria.
양서류 울음 소리 식별을 위한 특징 벡터 및 인식 알고리즘 성능 분석
박상욱,고경득,고한석,Park, Sangwook,Ko, Kyungdeuk,Ko, Hanseok 한국음향학회 2017 韓國音響學會誌 Vol.36 No.6
본 논문에서는 양서류 울음소리를 통한 종 인식 시스템 개발을 위해, 음향 신호 분석에서 활용되는 주요 알고리즘의 인식 성능을 평가했다. 먼저, 멸종위기 종을 포함하여 총 9 종의 양서류를 선정하여, 각 종별 울음소리를 야생에서 녹음하여 실험 데이터를 구축했다. 성능평가를 위해, MFCC(Mel Frequency Cepstral Coefficient), RCGCC(Robust Compressive Gammachirp filterbank Cepstral Coefficient), SPCC(Subspace Projection Cepstral Coefficient)의 세 특징벡터와 GMM(Gaussian Mixture Model), SVM(Support Vector Machine), DBN-DNN(Deep Belief Network - Deep Neural Network)의 세 인식기가 고려됐다. 추가적으로, 화자 인식에 널리 사용되는 i-vector를 이용한 인식 실험도 수행했다. 인식 실험 결과, SPCC-SVM의 경우 98.81 %로 가장 높은 인식률을 확인 할 수 있었으며, 다른 알고리즘에서도 90 %에 가까운 인식률을 확인했다. This paper presents the performance assessment of several key algorithms conducted for amphibian species sound classification. Firstly, 9 target species including endangered species are defined and a database of their sounds is built. For performance assessment, three feature vectors such as MFCC (Mel Frequency Cepstral Coefficient), RCGCC (Robust Compressive Gammachirp filterbank Cepstral Coefficient), and SPCC (Subspace Projection Cepstral Coefficient), and three classifiers such as GMM(Gaussian Mixture Model), SVM(Support Vector Machine), DBN-DNN(Deep Belief Network - Deep Neural Network) are considered. In addition, i-vector based classification system which is widely used for speaker recognition, is used to assess for this task. Experimental results indicate that, SPCC-SVM achieved the best performance with 98.81 % while other methods also attained good performance with above 90 %.