• Journal of Advanced Navigation Technology
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• v.26 no.1
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• pp.15-21
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• 2022

In this paper, we propose a method to implement an unequal power divider with different complex termination impedances for different output power ratios. The proposed method was designed using a matching the terminated complex impedances of the output port using only the transmission line, and presented an isolation circuits to satisfy the isolation characteristic between the terminating complex impedance ports. To prove the feasibility of this method, an unequal power divider with different load complex impedances with a splitting ratio k² = 3 dB and 1.7 dB and an unequal power divider with different complex termination impedances of all ports with a splitting ratio k² = 3 dB was designed at a center frequency of 2 GHz, and it was confirmed that the measured results of the electrical characteristics agree well the simulation.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.343-348
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• 2004

We report the design and basic operating characteristics of an radio frequency excited waveguide $CO_2$ laser. Four picecs of waveguide channels are placed in one laser cavity to increase a power per unit length with the form of a 2 ${\times}$ 2 matrix. Four independent optical outputs are measured from the front of output coupler, and these beams are combined to a Gaussian mode beam far from the output coupler. A 12 W output power has been obtained with $CO_2$ : $N_2$ : He : Xe = 1 : 1 : 3 : 0.2 of the gas mixture and 200 W of radio frequency.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10d
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• pp.526-528
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• 2002

본 논문은 CT 영상을 이용하여 체지방과 근육의 체적 및 비율을 분석하는 알고리즘 개발에 대하여 기술한다. CT 영상에는 체지방, 근육, 공기, 뼈등의 구성성분들이 서로 다른 명암값을 가지고 분포한다. 이 논문에서는 히스토그램을 통하여 각 구성성분에 대한 명암값을 찾아내었다. 찾아낸 명암값에 따라 체지방과 근육 그리고 뼈, 공기에 각각 색을 입혀 시각적으로 표현하여 체지방과 근육의 분포와 비율을 볼 수 있는 환경을 만들고 수치적으로 체적 및 비율의 결과 값을 출력하는 알고리즘을 개발하였다. 또한 단계적인 체지방 측정 프로그램을 위해 DB 환경을 구축하여 모든 자료를 저장하고 불러올 수 있는 환경을 만들어 체지방 측정 알고리즘을 완성하였다. 알고리즘은 돼지 실험에서 측정된 체지방과 비교하여 정확성을 검증한 결과 약 92.86%의 정확도를 보였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.78-79
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• 2022

In this paper, we propose a technique for tracking the classification and location of each user through body proportion analysis of the normalized skeletons of multiple users obtained using RGB-D cameras. To this end, each user's 3D skeleton is extracted from the 3D point cloud and body proportion information is stored. After that, the stored body proportion information is compared with the body proportion data output from the entire frame to propose a user classification and location tracking algorithm in the entire image.

• Journal of Advanced Navigation Technology
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• v.22 no.6
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• pp.642-647
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• 2018

In this paper, an unequal power divider based on adjusting electrical length of uniform transmission line is presented. This divider consists of three uniform transmission lines and one isolation resistor and have the different port impedances of input and output. The feature of proposed divider can changed the power dividing ratio to adjust only electrical length of uniform transmission lines. To verify the feasibility of proposed power divider, two divider circuits are designed, one is 1:2 power dividing ratio divider with $60{\Omega}$ uniform transmission line and $40{\Omega}$ input port impedances and $45{\Omega}$ output port impedances, the performance data were measured the insertion losses of 1.7 dB/ 5.0 dB, return losses of more than -30 dB and isolation of more than -35 dB. The other is 1:4 power dividing ratio divider with $40{\Omega}$ uniform transmission line and $50{\Omega}$ input port impedances and $75{\Omega}$ output port impedances, the performance data were measured the insertion losses of 1.3 dB/ 6.8 dB, return losses of more than -12 dB and isolation of more than -19 dB. The measured performance data agreed well with the simulated results.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.185-192
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• 2010

Design of velocity-compounded turbine for 75ton class LRE turbopump application and pressure compounded turbine for 30ton class LRE turbopump has been performed. 1D calculation and CFD analysis were conducted in determining blade and flow passage shape of velocity compounded turbine iteratively. Finally, 23.1% improved specific power and 5% reduced weight turbine to the original design was developed. In case of pressure-compounded supersonic turbine design, rotational speed was increased by 50% and the effect of carryover ratio, 2nd nozzle installation angle, leakage flow of 2nd nozzle, and work sharing factor was studied. Final 1D design resulted 36% increased specific power and 51% reduced weight comparing to the original single-row impulse turbine. It is anticipated that nozzle flow path design will be very important for the accomplishment of expected performance of pressure-compounded turbine and nozzle shape optimization will be conducted through the CFD analysis.

• Journal of Bio-Environment Control
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• v.20 no.4
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• pp.277-282
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• 2011

We carried out shape recognition. We found out cucumber's feature shape by means of neural network and back propagation algorithm. We developed an algorithm which finds object position and shape in real image and we gained following conclusion as a result. It was processed for feature shape extraction of cucumber to detect automatic. The output pattern rates of the miss-detected objects was 0.1~4.2% in the output pattern which was recognized as cucumber. We were gained output pattern according to image resolution $445{\times}363$, $501{\times}391$, $450{\times}271$, $297{\times}421$. It was appeared that no change was detected. When learning pattern was increased to 25, miss-detection ratio was 16.02%, and when learning pattern had 2 pattern, it didn't detect 8 cucumber in 40 images.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.12
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• pp.2685-2692
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• 2009

We propose pulsed magnetic stimulation below 30W by the AC(60Hz) switching control of leakage transformer primary which has some advantage of cost and size compared to a typical pulsed power supply. Pulse repetition rate is adjusted from 5Hz to 60Hz to control magnetic stimulation output. In this magnetic stimulation, a low voltage open loop control for high voltage discharge circuit is employed to avoid the HV sampling or switching and high voltage leakage transformer is used to convert rectified low voltage pulse to high voltage one. A ZCS(Zero Cross Switch)circuit and a DSP & FPGA are used to control gate signal of SCR precisely. The pulse repetition rate is limited by 60Hz due to the frequency of AC line and a high leakage inductance. The maximum magnetic stimulation output was obtained about 33W at pulse repetition rate of 60Hz, total 40, 80, 120, $160^{\circ}$, SCR gate trigger angle $90^{\circ}$ and total output.

• Journal of Oral Medicine and Pain
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• v.12 no.1
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• pp.5-16
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• 1987

레이저의 의학적 이용은 고출력 레이저의 외과적 이용과 더불어 많은 진전을 하게 되었다. 근래에는 인체에 손상을 주는 고출력 레이저 외에도 조직의 파괴없이 인체조직에 유용한 효과를 줄 수 있는 저출력 레이저에 대한 연구가 적극적으로 시도되고 있다. 본 연구는 치은염을 가진 13명의 대상에 대해 Split-mouth design으로 대조군 및 실험군을 설정하여 실험군의 치은에 저출력 레이저(Biotherapy dental Laser 3DL)를 격일로 4회 조사한 후 plaque index, pocket depth, sulcus bleeding index, supragingival과 subgingival plaque의 bacterial morphotype의 비율 및 광학현미경을 통한 조직학적 염증 침윤상을 측정 평가하여 다음과 같은 결과를 얻었다. 1) 레이저 조사후 SBI(p<0.01)는 감소하였으나 PI는 별다른 변화가 없었다. 2) 레이저 조사에 따라 spirochetes(p<0.01)를 포함하여 motiles(p<0.05, p<0.01)은 감소된 반면 nommotiles(p<0.05, p<0.01) 증가하였다. 3) 레이저 조사 치은에서는 염증세포 침윤이 Dental(p<0.05) 및 oral(p<0.01) 양측 모두 감소되었다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.4
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• pp.51-58
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• 2004

Push-pull structure with balun transformer is presented for load modulation technique which improves the overall efficiency of power amplifier Under the assumption that output impedance of fumed-off amplifier is high, conventional Doherty amplifier is composed of impedance inverter and peaking amplifier, of which operation is controlled by the input power level. In many case, however, impedance of 'off'amplifier is very low due to matching network or parasitic output capacitance. This paper introduces novel load modulation technique which uses low output impedance of 'off'amplifier. Experimental results show that good linearity and efficient!'enhancement of the proposed push-pull structure