• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2006년도 하계종합학술대회
• /
• pp.499-500
• /
• 2006

This paper presents a fast switching CMOS frequency synthesizer with a new coarse tuning method for PHS applications. To achieve the fast lock-time and the low phase noise performance, an efficient bandwidth control scheme is proposed. Charge pump up/down current mismatches are compensated with the current mismatch compensation block. Also, the proposed coarse tuning method selects the optimal tuning capacitances of the LC-VCO to optimize the phase noise and the lock-time. The measured lock-time is about $20{\mu}s$. This chip is fabricated with $0.25{\mu}m$ CMOS technology, and the die area is $0.7mm{\times}2.1mm$. The power consumption is 54mW at 2.7V supply voltage.

• 한국안전학회지
• /
• 제26권6호
• /
• pp.13-19
• /
• 2011

The purpose of this study is to examine the cause of damage to electrolytic capacitors and to present the heat generation mechanism in order to prevent the occurrence of similar problems. From the analysis results of electrolytic capacitors collected from accident sites, the fire causing area can be limited to the primary power supply for the initial accident. From the tests performed by applying overvoltage, surge, etc., it is thought that the fuse, varistor, etc., are not directly related to the accidents that occurred. The analysis of the characteristics using a switching regulator showed that the charge and discharge characteristics fell short of standard values. In addition, it is thought that heated electrolytic capacitors caused thermal stress to nearby resistances, elements, etc. It can be seen that the heat generation is governed by the over-ripple current, application of AC overvoltage, surge input, internal temperature increase, defective airtightness, etc. Therefore, when designing an electrolytic capacitor, it is necessary to comprehensively consider the correct polarity arrangement, appropriate voltage application, correct connection of equivalent series resistance(ESR) and equivalent series inductance(SEL), rapid charge and discharge control, sufficient margin of dielectric tangent, etc.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제13권2호
• /
• pp.108-113
• /
• 2013

This paper describes a low power asynchronous successive approximation register (SAR) type 12b analog-to-digital converter (ADC) for biomedical applications in a 0.35 ${\mu}m$ CMOS technology. The digital-to-analog converter (DAC) uses a capacitive split-arrays consisting of 6-b main array, an attenuation capacitor C and a 5-b sub array for low power consumption and small die area. Moreover, splitting the MSB capacitor into sub-capacitors and an asynchronous SAR reduce power consumption. The measurement results show that the proposed ADC achieved the SNDR of 68.32 dB, the SFDR of 79 dB, and the ENOB (effective number of bits) of 11.05 bits. The measured INL and DNL were 1.9LSB and 1.5LSB, respectively. The power consumption including all the digital circuits is 6.7 ${\mu}W$ at the sampling frequency of 100 KHz under 3.3 V supply voltage and the FoM (figure of merit) is 49 fJ/conversion-step.

• Transactions on Electrical and Electronic Materials
• /
• 제17권4호
• /
• pp.189-195
• /
• 2016

Micro Hotplate (MHP) is the key component in micro-sensors, particularly gas sensors. Indeed, in metal oxide gas sensors MOX, micro-heater is used as a hotplate in order to control the temperature of the sensing layer which should be in the requisite temperature range over the heater area, so as to detect the resistive changes as a function of varying concentration of different gases. Hence, their design is a very important aspect. In this paper, we have presented the design and simulation results of a meander micro heater based on three different materials - platinum, titanium and tungsten. The dielectric membrane size is 1.4 mm × 1.6 mm with a thickness of 1.4 μm. Above the membrane, a meander heating film was deposed with a thickness of 100 nm. In order to optimize the geometry, a comparative study by simulating two different heater thicknesses, then two inter track widths has also been presented. Power consumption and temperature distribution were determined in the micro heater´s structure over a supply voltage of 5, 6, and 7 V.

• ETRI Journal
• /
• 제46권3호
• /
• pp.550-563
• /
• 2024

A novel inductance simulation circuit employing only two dual-output voltage-differencing buffered amplifiers (DO-VDBAs) and a single capacitance (grounded) is proposed in this paper. The reported configuration is a purely resistor-less realization that provides electronically controllable realized inductance through biasing quantities of DO-VDBAs and does not rely on any constraints related to matched values of parameters. This structure exhibits excellent behavior under the influence of tracking errors in DO-VDBAs and does not exhibit instability at high frequencies. The simple and compact metal-oxide semiconductor (MOS) implementation of the DO-VDBAs (eight MOS per DO-VDBA) and adoption of grounded capacitance make the proposed circuit suitable for on-chip realization from the perspective of chip area consumption. The function of the pure grounded inductance is validated through high pass/bandpass filtering applications. To test the proposed design, simulations were performed in the PSPICE environment. Experimental validation was also conducted using the integrated circuit CA3080 and operational amplifier LF-356.

• 대한전자공학회논문지SD
• /
• 제43권12호
• /
• pp.65-73
• /
• 2006

본 논문에서는 각종 지능형 센서, control system 및 battery-powered system 응용과 같이 고해상도, 저전력 및 소면적을 동시에 요구하는 시스템을 위한 14b 200KS/s $0.87mm^2$ 1.2mW 0.18um CMOS 알고리즈믹 A/D 변환기 (ADC)를 제안한다. 제안하는 ADC는 요구되는 해상도 및 속도 사양을 만족시키면서, 동시에 면적을 최소화하기 위해 입력단 샘플-앤-홀드 앰프를 전혀 사용하지 않는 알고리즈믹 구조를 채택하였으며, 전체 ADC의 전력소모를 최소화하기 위해 핵심 아날로그 회로 부분에는 향상된 스위치 기반의 바이어스 전력 최소화 기법을 제안하였고, multiplying D/A 변환기에는 클록 선택적인 샘플링 커패시터스위칭 기법을 적용하였다. 또한, 초저전력 온-칩 기준 전류 및 전압 발생기를 제안하여 전체 ADC의 전력소모를 최소화하였다. 제안하는 시제품 ADC는 0.18um 1P6M CMOS 공정으로 제작되었으며, 측정된 DNL 및 INL은 각각 최대 0.98LSB 및 15.72LSB 수준을 보인다. 또한, 200KS/s의 동작 속도에서 SNDR 및 SFDR이 각각 최대 54dB, 69dB이고, 전력 소모는 1.8V 전원 전압에서 1.2mW이며 제작된 ADC의 칩 면적은 $0.87mm^2$이다

• 한국방사선학회논문지
• /
• 제12권5호
• /
• pp.645-650
• /
• 2018

본 연구는 면적선량에 따른 영상의 농도를 측정하여 피폭선량에 대한 정도관리 필요성을 제시하고자 하였다. 관전압을 80 kVp로 고정하고 관전류를 1, 25, 50, 80, 100 mAs로 조사한 결과 면적선량은 25 mAs에서 50 mAs로 증가하면 1.88배의 선량이 증가하고 50 mAs에서 100 mAs로 증가하면 2.05배 증가하였다. 하지만 필름으로 획득한 영상의 농도는 25 mAs에서 50 mAs로 증가하면 48% 증가하고, 50 mAs에서 100 mAs로 증가하면 29% 증가하였다. 또한 DR 영상의 농도는 25 mAs에서 50 mAs로 증가하면 12% 증가하고, 50 mAs에서 100 mAs로 증가하면 30% 증가하는 것으로 나타났다. 즉, 디지털 영상촬영 장비는 적정 촬영 조건에서 선량 증가에 따른 영상의 농도차이가 필름 영상보다는 적게 나타났다. 본 연구의 결과에서 디지털 영상 촬영 장비를 사용하는 의료기관에서는 방사선 선량에 대한 정도관리를 통하여 현재보다 촬영 부위별 피폭선량을 조금이나마 더 줄일 수 있을 것으로 판단되어진다.

• Journal of Chest Surgery
• /
• 제12권4호
• /
• pp.350-354
• /
• 1979

The incidence of congenital aortic valvular stenosis has been known rare, and approximately 3-6% of congenital heart diseases. Recently, we experienced 1 case of congenital aortic valvular stenosis, and which was corrected surgically under extracorporeal circulation successfully. A 11 years old male pt. was admitted to N.M.C. because of dyspnea, dizziness, chest pain and episode of syncope. An auscultation, harsh systolic murmur [Gr. IV/VI] was noted at aortic area and also palpable strong thrill. ECG showed LVH c strain pattern and suspicious LVH finding in simple chest P-A film. In Lt. cardiac catheterization, abrupt pressure change [110mmHg] between LV & Aorta was noted across the aortic valve. And aortic insufficiency was absent, well visualized both coronary arteries and suspicious bicuspid aortic valve in aortography. Valve form was bicuspid, large one was noncoronary cusp and another cusp was Rt. & Lt. coronary cusp which was interpositioned rudimentary commissure. Central aortic orifice was about 5ram in diameter. Valvulotomy was done along the fusioned commissure between noncoronary cusp and Rt. & Lt.coronary cusp, and then short incision was added between Rt. coronary cusp & Lt. coronary cusp. Immediate postoperative course smooth but unknown cardiac arrest was noted in POD second day. Complete recovery was done without sequelae by resuscitation. After operation, clinical symptoms were subsided but systolic murmur [Gr. II/VI] was audible at aortic area, diastolic murmur was absent. ECG showed still remained LVH but much decreased R wave voltage in Lt. precordial leads. Simple chest P-A showed no interval changes compared to preop film. Control Lt. heart catheterization revealed still remained pressure gradient [40ramrig] between LV & Aorta. But much decreased pressure gradient compared to preop pressure gradient [110mmHg].

• 한국의학물리학회지:의학물리
• /
• 제32권4호
• /
• pp.153-158
• /
• 2021

Purpose: This study evaluated the features of a pressure mapping system for patient motion monitoring in radiation therapy. Methods: The pressure mapping system includes an MS 9802 force sensing resistor (FSR) sensor with 2,304 force sensing nodes using 48 columns and 48 rows, controller, and control PC (personal computer). Radiation beam attenuation caused by pressure mapping sensor and signal perturbation by 6 and 10 mega voltage (MV) photon beam was evaluated. The maximum relative pressure value (mRPV), average relative pressure value (aRPV), the center of pressure (COP), and area of pressure distribution were obtained with/without radiation using the upper body of an anthropomorphic phantom for 30 minutes with 15 MV. Results: It was confirmed that the differences in attenuation induced by the FSR sensor for 6 and 10 MV photon beams were small. The differences in mRPV, aRPV, area of pressure distribution with/without radiation are about 0.6%, 1.2%, and 0.5%, respectively. The COP values with/without radiation were also similar. Conclusions: The characteristics of a pressure mapping system during radiation treatment were evaluated on the basis of attenuation and signal perturbation using radiation. The pressure distribution measured using the FSR sensor with little attenuation and signal perturbation by the MV photon beam would be helpful for patient motion monitoring.

• Smart Structures and Systems
• /
• 제29권5호
• /
• pp.653-660
• /
• 2022

Gravel scattering that is generated during operation of high-speed railway vehicle is cause to damage of vehicle such as windows, axle protector and so on. Especially, those are frequently occurred in winter season when snow ice is generated easily. Above all, damage of vehicle windows has not only caused maintenance cost but also increased psychological anxiety of passengers. Various methods such as heating system using copper wire, heating jacket and heating air are applied to remove snow ice generated on the under-body of vehicle. However, the methods require much run-time and man power which can be low effectiveness of work. Therefore, this paper shows that large-area heating system was developed based on heating coat in order to fundamentally prevent snow ice damage on high-speed railway vehicle in the winter season. This system gives users high convenience because that can remotely control the heating system using IoT-based wireless communication. For evaluating the applicability to railroad sites, a field test on an actual high-speed railroad operation was conducted by applying these techniques to the brake cylinder of a high-speed railroad vehicle. From the results, it evaluated how input voltage and electric power per unit area of the heating specimen influences exothermic performance to draw the permit power condition for icing. In the future, if the system developed in the study is applied at the railroad site, it may be used as a technique for preventing all types of damages occurring due to snow ice in winter.