• 동의생리병리학회지
• /
• 제24권1호
• /
• pp.42-47
• /
• 2010

The pulse diagnosis is an important method in Oriental Medicine. Recently, there have been continuous attempts to replace the finger palpation by Oriental medical doctors (OMDs) by more objective tools based on machines, e.g., pulse analyzers. To improve the performance of the pulse analyzers, both the machine-appropriate interpretations for the pulse images appeared in the literature and the improvement in the repeatability and reproducibility of the measurement sensors are to be developed. As an attempt towards the transformation of the pulse images in terms of machine-appropriate language, in this work, we suggest an upgraded algorithm for the solid/deficient pulses, which are the two representative pulse images informing us how strong the pulse pressure is. It has been argued that one could determine the solid/deficient pulses by the maximum pulse pressure from pulse analyzers. However, by a clinical test, we found that the maximum pulse pressure alone is not sufficient to determine the solid/deficient pulses. In addition to the maximum pulse pressure, the mean pulse pressure averaged over for five different hold-down pressures(3-D MAC) is needed to improve the agreement with the OMD's decision for the solid/deficient pulse. We found that, among the data diagnosed with having either the solid pulse or deficient pulse by OMDs, the novel algorithm showed 86.0% diagnosis rate and 81.6% concordance rate.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2010년도 제34회 춘계학술대회논문집
• /
• pp.133-137
• /
• 2010

하나의 고체 추진기관에서 이중펄스 추력을 발생시키는 기술은 기존의 일회성 추력발생 방식에 비하여 여러 가지 장점이 있다. 추진기관에 펄스분리장치를 적용하면 적절한 추력배분을 통하여 유도탄의 사거리 연장 및 종말속도를 향상시킨다. 본 연구에서는 격벽형 펄스분리장치의 성능을 검증하기 위하여 소형 추진기관을 설계, 제작하여 지상연소시험을 수행하였다. 이를 통하여 펄스분리장치의 파열특성, 구조적 안전성 및 내열특성 등을 확인하였으며 향후 실물형 이중펄스 추진기관 설계 시 필요한 데이터 등을 확보하였다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2011년도 제37회 추계학술대회논문집
• /
• pp.69-72
• /
• 2011

지상연소시험을 통해 이중펄스모타 성능을 입증하였다. 이중펄스를 구현하기위해 고체로켓모타 내부에 격벽형 펄스분리장치와 독립적인 점화기를 설치하였다. 주요 개발목표는 세부분으로 나뉘어진다. 첫째, 이중펄스 추진기관의 총역적은 동일형상 및 무게를 갖는 고체로켓모타에 비해 총역적이 90% 이상이어야 한다. 둘째, 1단 펄스 종료 후 1 ~ 60초 중 임의의 시간 후 2단 펄스를 점화시킬 수 있어야 한다. 마지막으로, 펄스분리장치는 1단 펄스 작동압력에서 견디며 2단 작동압력의 30% 이하에서 파열되어야 한다. 지상연소시험 결과 이러한 개발목표를 달성하는 것을 확인하였다.

• 대한전자공학회논문지TC
• /
• 제46권12호
• /
• pp.22-29
• /
• 2009

본 논문에서는 X-대역 펄스압축 반도체형 레이다를 위한 200W SSPA를 개발하였다. 개발한 X-대역 SSPA는 전치증폭단, 구동증폭단, 고출력을 위한 주전력 증폭단의 3단 연계구조형 증폭기로 구성되어있다. X-대역에서 200W 이상의 출력을 내기 위해 주전력 증폭단은 충분한 이득과 전력을 얻을 수 있는 GaN HEMT소자를 사용하여 병렬구조로 설계하였다. 개발한 SSPA는 주파수범위 9.2-9.6GHz, 펄스주기 1ms, 펄스폭 100us, 듀티사이클 10% 조건에서 전체이득 59dB 이상, 출력전력 200W이상의 성능을 가진다. 본 논문에서 개발한 SSPA는 펄스압축기술을 이용한 고품위 반도체 레이다시스템에 적용할 수 있다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.215-217
• /
• 2001

This paper describes an all solid-state switch pulse generator for various applications where square pulse voltage is required. The pulse generator produces various voltage pulses: voltage $5{\sim}100kV$. current $10{\sim}200A$, pulse width $1{\sim}10{\mu}sec$, repetition rate up to 500Hz. The output power is the combination of these parameters up to 10kW. It consists of a DC-DC converter and several pulse generating modules which are connected in series to obtain higher pulse voltage. Each module contains semiconductor switches (IGBT's), energy storage capacitors and control units to trigger switches. The structure and operational principle are described and the protection circuit for reliable operation is suggested. Experimental results show that the pulse generator can be used for applications with nonlinear loads.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2011년도 제37회 추계학술대회논문집
• /
• pp.942-948
• /
• 2011

고체추진기관은 구조가 비교적 간단하고 장기적 저장성이 우수한 반면에 일반적으로 추력의 조절등에 한계성을 가지고 있다. 본 논문에서는 구현의 용이함과 에너지 효율성이 좋은 on-off 제어기법을 이용한 가변추력 고체추진 기관의 압력 제어를 위한 제어기를 소개한다. 연소기 내 압력제어를위해 질량보존만을 고려한 추진기관의 연소기 내 압력변화 모델에 대하여 고전적인 비례-적분 제어기와 같은 연속적 제어 기법과 PWM, PWPFM과 같은 on-off 제어기를 설계하고 시뮬레이션을 통해 결과를 비교한다.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2013년도 추계학술대회 논문집
• /
• pp.186-187
• /
• 2013

The paper presents a long-pulse modulator for klystron using a high-voltage solid-state switch and a droop compensator. The modulator guarantees the safe of klystron by limiting the amount of energy transferred to klystron in case of arc. The high performance of the modulator is also achieved by the fast transition time, high flatness and average power. The proposed prototype has produced pulses with a flat-top voltage -90[kV], pulse width 1ms and pulse frequency 200[Hz]. The validity of the long-pulse modulator for klystron has been verified by the simulation and experimental works.

• 한국자기공명학회논문지
• /
• 제26권4호
• /
• pp.51-58
• /
• 2022

The baseline flattened NMR spectrum has been achieved by several methodologies including pulse manipulation with a series of phase cycling. The background signal inherent in the probe is also main source of baseline distortion both in solution and solid NMR. The simple direct polarization with 90° pulse flipping the magnetization from the z-axis onto the receiver coil requires the strong rf pulse enough to encompass the wide frequency range to excite the resonance of interest nuclei. Albeit the perfect polarization 90° pulse, the signal from the unwanted magnetic fields such as background signal can not be completely suppressed by suitable phase cycling. Moreover, slowly baseline wiggling signal from the low 𝛾 nuclei is not easy to eliminate with multiple pulse manipulation. So there is still need to contrive the new scheme for that purpose in an adroit manner. In this article new triple pulse excitation schemes for TIP and modified DEPTH pulse sequence are analytically examined in terms of arbitrary phase and flip angle of pulse. The suitable phase cycling for these pulse trains is necessary for the good sensitivity and resolution of the spectrum. It is observed that the ¹³C sensitivity TIP experiment is almost equal to the CP/MAS with modified DEPTH sequence, both of which are applicable to both solid and solution state NMR.

• Journal of Electrical Engineering and Technology
• /
• 제1권4호
• /
• pp.528-533
• /
• 2006

Electrical discharges may occur in gas, liquid as well as solid insulating materials. This paper describes the investigation results on the discharges in air, silicone oil and low density polyethylene (LDPE) using needle plane electrode system under AC voltage of 50 Hz. The experimental results showed that for discharge in air (corona), discharge pulses were concentrated around the peak of applied voltage at negative half cycle. For silicone oil positive as well as negative discharges were observed which concentrated around the peak of applied voltage. The positive pulse number was smaller but the magnitude was higher than that of negative discharge. Discharges in void took place at wider range of phase of applied voltage. The unbalance in pulse number and magnitude similar to that of oil discharges were observed. For electrical treeing in LDPE, the discharges were spread before the zero cross of the applied voltage up to the peak at both positive and negative half cycles. The discharge pulse sequence analysis indicated that the PD occurrence in air, oil and void were strongly affected by the magnitude of applied voltage. However, for electrical treeing it was observed that the discharge occurrence was strongly affected by the time derivative of the applied voltage (dv/dt).

• 한국전자파학회:학술대회논문집
• /
• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
• /
• pp.91-96
• /
• 2005

In this paper, describes the design and performance of a 1.5 kW solid-state pulsed power amplifier, operating over 2.7-2.9 GHz at a duty of 10% and with a pulse width of 100 us for radar application. The solid-state pulsed power amplifier configures a series of 8-stage cascaded power amplifier with different RF output power levels. Low loss Wilkinson combiners are used to combine output powers of six 300W high power solid state modules. Tests show peak output power of 1.61 kW, corresponding to PAE of 26.2% over 2.7-2.9 GHz with pulse width of 100 us and a PRF of 1 kHz.