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- 저자 : 최병하 (검색결과 181 건)
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최병하 木浦海洋大學校 2000 論文集 Vol.8 No.2
This paper has designed and fabricated the low power transmitter and receiver to use 447MHz. The properties have been satisfied the several characteristics to provide the Radio Administration-Law. And so, It is possible to use fabrication the lifesaving low power radio system.
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운동매질내에서의 Circula Loop Antenna의 방사특성(II)
최병하 대한전자공학회 1972 전자공학회지 Vol.9 No.2
본논문에서는 운동매질내에서 크기가 파장과 동등정도이거나 그 이상인 circular loop antenna의 방사특성을 전류분포가 정현파적인 경우에 대하여 고찰하였다. 고찰결과로는 방사특성이 매질속도의 영향을 받는다는 사실과 그 영향으로는 정지매질의 radiation pattern 과 비교하여 방사지향성이 loop antenna면에 평행인 매질속도성분에만 영향을 받고 수직성분속도에는 무관하며 radiation pattern의 최대지향성은 loop면에 평행인 속도성분방향으로 이동하고 이와 반대방향으로는 Pattern의 크기가 증가하게 된다. 또 이와 같은 운동매질의 영향은 매질속도도가 오고 전류주파수가 높을수록 antenna의 직경이 클수록 더욱 현저하게 된다는 사실을 알게 되었다. In this paper, the radiation characteristics of a large circular loop antenna with sinusoidal current distribution is studded in a moving media with a constant velocity much less than the speed of light. The diameter of the circular loop antenna is comparable with or larger than wave length. In studing the radiation characteristics, vector potential for the antenna is derived and relative field pattern is plotted from the vector potentials. Finally the field patterns are compared with those of stationary media. It is found that maximum directivities are shifted to the direction of the velocity of the media, and the field intensities are decreased in that direction and increased in opposite direction by the velocity component paralell to the loop plane. It is also found that the deviations for the pattern are proportional to the velocity of the media, the frequency of the distributed current, the diameter of the loop antenna, and the daviation depends only upon the parallel component of the velocity to the loop plane.
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崔秉河,卞種秀,李相韓 慶北大學校 齒科大學 1985 慶北齒大論文集 Vol.2 No.1
The author studied the heart rate changes of 150 adult patients (79 male and 71 females above 18-years old) under dental local anesthesia, and heart rate changes for breathholding alone of 20 patients. The heart rate is best reflection of the activity of the autonomic nerve system and the easiest physiological sign to monitor. The purpose of this study was to find out cardiac activity under dental local anesthesia, thereafter to clarify the mechanism of syncope from the aspect of trigeminal-vagal reflex. The studied group were devided into four. GⅠ: Local anesthesia with a different agent by epinephrine concentration and normal saline as a control. GⅡ: Local anesthesia after premedication of atropione. GⅢ: Local anesthesia under the general aensthesia. GⅣ: Heart rate changes for breathholding alone. The result were as follows: The heart rate was decreased in 138(92%) of 150 patients during local anesthetic injection, and increascd after injection. This means the possible participation of trigeminal-vagal reflex in producing heart rate decrease. Mean maximum decrease rate of G I was 14.2±7.54%, and not affected by anesthetic agents(p>0.05) Mean value (GⅡ) was 6.89±4.38%, which means that atropine inhibits the reflex partially(p<0.05). Mean value (GⅢ) was 1.20±0.77%, which means that general anesthesia blocked the reflex completly. Mean value (GⅣ) was 6.58±3.13%, which is not reached to changes by local anesthesia.
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갈륨비소 MESFET를 이용한 고이득 차동 증폭기 설계
최병하,김학선,김은로,이형재 한국통신학회 1992 韓國通信學會論文誌 Vol.17 No.8
본 논문에서는 갈륨비소 연산 증폭기의 입력단 설계에 있어서 기초가 되는 차동 증폭기에 사용될 이득 증가 기법을 적용한 단일 증폭기와 새로운 구성의 전류 미러를 설계하였다.차동 전압 이득을 높이기 위하여 단일 증폭기의 bootstrap 이득 증가 기법을 이용하여 차증 증폭기를 구성하였다. 차동 증폭기에 사용되는 정전류원으로서 주파수 특성이 우수한 선형 역상 전류 미러를 사용하여 회로의 안정화를 꾀하였다. 또한, 동상 전압 이득을 감소시키기 위하여 common mode feedback을 사용함으로써 차동 증폭기의 성능 평가에 있어서중요한 CMRR을 높였다.PSPICE를 통한 시뮬레이션 결과, 기본 단일 증폭기의 이득은 29.dB인데 비하여 새로 설계된 new bootstrapped 이득 증가 기법을 사용한 경우에는 57.67db로써 이득이 28.26dB 개선되었음을 알 수 있었다. 또한, 본 논문에서 설계한 차동 증폭기는 차동 이득이 57.66dB, CMRR이 83.98dB로써 기존의 논문보다 향상되었고 주파수 특성면에서도 차단 주파수가 23.26GHz로써 우수함을 입증하였다. In this paper, a circuit design techniques for Improving the voltage gain of the GaAs MESFET single amplifier is presented. Also, various types of existing current mirror and proposed current mirror of new configuration are compared. To obtain the high differential mode gain and low common mode gain, bootstrap gain enhancement technique Is used and common mode feedback Is employed In the design of differential amplifier. The simulation results show that designed differential amplifier has differential gain of 57.66dB, unity gain frequency of 23.25GHz. Also, differential amplifier using common mode feedback with alternative negative current mirror has CMRR of 83.S8dB, stew rate of 3500 V /\ulcorners.
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최병하 木浦海洋大學校 1999 論文集 Vol.7 No.2
Nowadays, many radio communication apparatus is used to the CDMA System. This paper has been studied on the inspection-inventory, improvement scheme and inspection technology of the CDMA system and Terrestrial Digital TV. To this result, it must be to add a measurement of ρ and Code Domain Power in the COMA. AND so, it is necessary to measure of the Out-Band Radiated Characteristic, Desired to Undesired Ration, In-Band Radiated Characteristic, Desired to Undesired Ratio, In-Band signal Characteristic, Inter Symbol Interference and Bit Error Rate in the Terrestrial Digital TV.
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셀룰러방식 이동전화용 저잡음 증폭기의 설계에 관한 연구
최병하 木浦海洋大學校 1998 論文集 Vol.6 No.2
In designing RF amplifiers two methods are frequently. One is to design small signal amplifiers using S-parameters, the other one is to design large signal amplifiers with equivalent input/output impedance networks for transistor. In this paper, Low Noise Amplifier is designed using S-parameters for the cellular-phone Designing focuses are low cost and improvements of the performance.
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崔炳夏 木浦海洋大學校 1994 論文集 Vol.2 No.1
It is un-satisfactory and bad-quality of the SSB & VHF voice communication system for a small vessel. The Trunked Radio System is good-quality and possibility to access easy, all call, group call and urgent call. This paper propose a new communication service system using TRS in a small vessel sailing along shore.
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