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A Programmable Pulser-Receiver Circuit for Single Transducer Medical Ultrasound System
박현태,엄지용 한국과학기술원 반도체설계교육센터 2021 IDEC Journal of Integrated Circuits and Systems Vol.7 No.4
This work presents a proof-of-concept pulser-receiver circuit for a single-transducer-based medical ultrasound system. The proposed circuit consists of a high-voltage pulser and a preamplifier. The pulser can generate an arbitrary pulse waveforms by adjusting external digital control signals. Also, the proposed pulser can drive a transducer with a capacitive load of several nF at a frequency up to 10 MHz by using a single-stack output stage. To reduce an active area, the return-to-ground path of pulser is reused as a transmit/receive switch during an echo-acquisition period. The mid-band gain of preamplifier can be adjusted, and the achieved maximum gain is 45 dB. The input-referred noise voltage of preamplifier is 5.1 Vrms at the maximum gain condition. The proposed ultrasonic pulser-receiver circuit was fabricated in a 180-nm BCD process. The pulser operates at supply voltages of ±10 V, and the preamplifier operates at supply voltages of ±0.9 V. The active area of fabricated chip is 1.09 mm2.
박현태,이두순,박기환 한국농촌경제연구원 2001 농촌경제 Vol.24 No.2
The pot-plants are various and have the characteristic of sensitivity to vogue. Recently Japan`s pot-plants have grown continuously due to becoming gardening. Moreover the structure of Korea`s flower exports is concentrated toward Japan. So the export potential of pot-plants toward Japan seems bright. Therefore, the structure of Japan`s flower market, and consumption preference need to be investigated in order to expand exports. If the strategy items through such investigation and analysis are exported, pot-plants growers will have an opportunity for overcoming current difficulties.
3.2t 보론강 판재 직수냉각 핫스탬핑시 냉각수 유량에 따른 미세조직 및 기계적 특성
박현태,권의표,임익태,Park, Hyeon Tae,Kwon, Eui Pyo,Im, Ik Tae 한국재료학회 2020 한국재료학회지 Vol.30 No.12
Direct water quenching technique can be used in hot stamping process to obtain higher cooling rate compared to that of the normal die cooling method. In the direct water quenching process, setting proper water flow rate in consideration of material thickness and the size of the area directly cooled in the component is important to ensure uniform microstructure and mechanical properties. In this study, to derive proper water flow rate conditions that can achieve uniform microstructure and mechanical properties, microstructure and hardness distribution in various water flow rate conditions are measured for 3.2 mm thick boron steel sheet. Hardness distribution is uniform under the flow condition of 1.5 L/min or higher. However, due to the lower cooling rate in that area, the lower flow conditions result in a drastic decrease in hardness in some areas in the hot-stamped part, resulting in low martensite fraction. From these results, it is found that the selection of proper water flow rate is an important factor in hot stamping with direct water quenching process to ensure uniform mechanical properties.
자궁내막암과 동시에 발생한 자궁천골인대의 자궁내막증에서 유래된 선암
박현태,서동주,한지운,설현주,김인선,강재성 대한부인종양 콜포스코피학회 2003 Journal of Gynecologic Oncology Vol.14 No.4
1920년대 초반부터 자궁내막증에서 유래하는 약성 종양에 대하여 서술되고 있다. 불충분한 보고와 엄격한 진단 범주에의 적용 미숙으로 인하여 정확한 빈도는 알수 없지만 자궁내막증 환자의 1-2% 정도 정도롤 추축되고 있다. 자궁 내막암과 동시에 발생한 자궁내막증에서 유래된 선암 1예가 있어 문헌 고찰과 함께 보고하는 바이다. The existence of malignancies arising in endometriosis has been appreciated since the early 1920's. The exact incidence is difficult to determine due to underreporting and failure to apply strict diagnostic criteria, but is thought to be in the range of 1-2% of patients with endometriosis. A case of adenocarcinoma arising in endometriosis with simultaneous endometrial carcinoma is prosented and the literatures are reviewed.
박현태,권의표,임익태,Park, Hyeon Tae,Kwon, Eui Pyo,Im, Ik-Tae 한국재료학회 2019 한국재료학회지 Vol.29 No.12
In this study, the direct water quenching technique is applied to validate the applicability of direct water quenching as a cooling method in the hot stamping process of 3.2 mm thick boron steel sheet. Cooling performance of conventional die quenching and direct water quenching is compared. Higher cooling rate is obtained by hot stamping with direct water quenching compared to die quenching. As the flow rate of cooling water increases, the cooling rate increases, and a high cooling rate of 71 ℃/s is achieved under flow rate conditions of 0.8 L/min. Through direct water quenching, the cooling time required for sufficient cooling of the sheet is reduced. Full martensitic microstructure is obtained under flow rate condition of 0.8 L/min. Hardness increases with increasing flow rate. From these results, it is verified that the direct water quenching is applicable to the hot stamping of thick boron steel sheet.