DC/DC 전력 컨버터의 전류모드 PWM 제어기의 방사선 영향

노영환(Young Hwan Lho),황의성(Eui Sung Hwang),노경수(Kyeoung Su Lho),푸파논(Phouphanonh),캄푸는(Khamphoungeun),한창운(Chang Won Han) 한국철도학회 2011 한국철도학회 학술발표대회논문집 Vol.2011 No.10

DC/DC switching power converters produce DC output voltages from different DC input sources. The converters can be used in regenerative braking of DC motors to return energy back in the supply resulting in energy savings for the systems containing frequent stops. The current mode DC/DC converter is composed of a PWM (pulse width modulation) controller a MOSFET and inductor etc. Pulse width modulation is applied to control and regulate the total output voltage. It is shown that the variation of threshold voltage at MOSFET and the offset voltage increase caused by radiation effects make the PWM pulse unstable. In the PWM operation the missing pulses the changes in pulse width and a change in the period of the output waveform are studied by simulation program with integrated circuit emphasis (SPICE) and experiments.

Changes in Glucose Metabolism in Vertical Sleeve Gastrectomy

Lho, Y.,Roux, C. W.,Park, H. S.,Kim, G. S.,Jung, J.,Hwang, G. S.,Seo, Y. K.,Ha, T. K.,Ha, E. RAPID COMMUNICATIONS 2015 OBESITY SURGERY Vol.25 No.11

Design of Super-junction TMOSFET with Embedded Temperature Sensor

Lho, Young Hwan Institute of Korean Electrical and Electronics Eng 2015 전기전자학회논문지 Vol.19 No.2

Super-junction trench MOSFET (SJ TMOSFET) devices are well known for lower specific on-resistance and high breakdown voltage (BV). For a conventional power MOSFET (metal-oxide semiconductor field-effect transistor) such as trench double-diffused MOSFET (TDMOSFET), there is a tradeoff relationship between specific on-state resistance and breakdown voltage. In order to overcome the tradeoff relationship, a SJ TMOSFET structure is suggested, but sensing the temperature distribution of TMOSFET is very important in the application since heat is generated in the junction area affecting TMOSFET. In this paper, analyzing the temperature characteristics for different number bonding for SJ TMOSFET with an embedded temperature sensor is carried out after designing the diode temperature sensor at the surface of SJ TMOSFET for the class of 100 V and 100 A for a BLDC motor.

The Implementation of Testing Board forSingle Event Upsets

Lho, Young-Hwan,Kim, Ki-Yup The Korean Society for Aeronautical and Space Scie 2004 International Journal of Aeronautical and Space Sc Vol.5 No.2

One of the major problem encountered in nuclear plants and satellites design isEMI (Electro-Magnetic Interference) and EMC (Electro-Magnetic Compatibility).Here, our focus is to implement the test board for checking SEU (Single EventUpsets); the effects of protons on the electronic system. The SEU results from thelevel change of stored information due to photon radiation and temperature in thespace environment. The impact of SEU on PLD (Programmable Logic Devices)technology is most apparent in ROM/SRAM/DRAM devices wherein the state ofstorage cell can be upset. In this paper, a simple and powerful test techniques issuggested, and the results are presented for the analysis and future reference. In ourexperiment, the proton radiation facilitv (having the energy of 50 MeV with a beamcurrent of 60 uA of cyclotron) available at KIRAMS (Korea Institute of RadiologicalMedical Sciences) has been applied on a commercially available SRAM manufacturedby Hynix Semiconductor Company.

A Feedback Circuit of Effective Wireless Power Transfer for Low Power System

Lho, Young Hwan Institute of Korean Electrical and Electronics Eng 2018 전기전자학회논문지 Vol.22 No.2

Wireless power transfer (WPT) is the technology that forces the power to transmit electromagnetic field to an electrical load through an air gap without interconnecting wires. This technology is widely used for the applications from low power smartphone to high power electric railroad. In this paper, the model of wireless power transfer circuit for the low power system is designed for a resonant frequency of 13.45 MHz. Also, a feedback WPT circuit to improve the power transfer efficiency is proposed and shown better performance than the original open WPT circuit, and the methodology for power efficiency improvement is studied as the coupling coefficient increases above 0.01, at which the split frequency is made.

Implementation of Effective Wireless Power Transmission Circuit for Low Power System

Lho, Young Hwan Institute of Korean Electrical and Electronics Eng 2018 전기전자학회논문지 Vol.22 No.3

Wireless power transfer (WPT) is the technology that enables the power to transmit electromagnetic field to an electrical load without the use of wires. There are two kinds of magnetic resonant coupling and inductive coupling ways transmitting from the source to the output load. Compared with microwave method for energy transfer over a long distance, the magnetic resonance method has the advantages of reducing the barrier of electromagnetic wave and enhancing the efficiency of power transmission. In this paper, the wireless power transfer circuit having a resonant frequency of 13.45 MHz for the low power system is studied, and the hardware implementation is accomplished to measure the power transmission efficiency for the distance between the transmitter and the receiver.

Structure Modeling of 100 V Class Super-junction Trench MOSFET with Specific Low On-resistance

Lho, Young Hwan Institute of Korean Electrical and Electronics Eng 2013 전기전자학회논문지 Vol.17 No.2

For the conventional power metal-oxide semiconductor field-effect transistor (MOSFET) device structure, there exists a tradeoff relationship between specific on-resistance ($R_{ON.SP}$) and breakdown voltage ($V_{BR}$). In order to overcome the tradeoff relationship, a uniform super-junction (SJ) trench metal-oxide semiconductor field-effect transistor (TMOSFET) structure is studied and designed. The structure modeling considering doping concentrations is performed, and the distributions at breakdown voltages and the electric fields in a SJ TMOSFET are analyzed. The simulations are successfully optimized by the using of the SILVACO TCAD 2D device simulator, Atlas. In this paper, the specific on-resistance of the SJ TMOSFET is successfully obtained 0.96 $m{\Omega}{\cdot}cm^2$, which is of lesser value than the required one of 1.2 $m{\Omega}{\cdot}cm^2$ at the class of 100 V and 100 A for BLDC motor.

A Methodology of Dual Gate MOSFET Dosimeter with Compensated Temperature Sensitivity

Lho, Young-Hwan Institute of Korean Electrical and Electronics Eng 2011 전기전자학회논문지 Vol.15 No.2

MOS (Metal-Oxide Semconductor) devices among the most sensistive of all semiconductors to radiation, in particular ionizing radiation, showing much change even after a relatively low dose. The necessity of a radiation dosimeter robust enough for the working environment has increased in the fields of aerospace, radio-therapy, atomic power plant facilities, and other places where radiation exists. The power MOSFET (Metal-Oxide Semiconductor Field-Effect Transistor) has been tested for use as a gamma radiation dosimeter by measuring the variation of threshold voltage based on the quantity of dose, and a maximum total dose of 30 krad exposed to a $^{60}Co$ ${\gamma}$-radiation source, which is sensitive to environment parameters such as temperature. The gate oxide structures give the main influence on the changes in the electrical characteristics affected by irradiation. The variation of threshold voltage on the operating temperature has caused errors, and needs calibration. These effects can be overcome by adjusting gate oxide thickness and implanting impurity at the surface of well region in MOSFET.

콘크리트 슬래브의 미진동 제어

Lho, Byeong Cheol,Byun, Keun Joo,Yang, Jae Sung 한국지진공학회 1998 한국지진공학회논문집 Vol.2 No.4

본 연구는 허용진동환경을 만족하기 위한 콘크리트 슬래브의 미진동해석 및 제어기법에 관한 것이다. 본 연구에서는 제시된 방법은 임의 두 점간의 전달 함수와 가속 도로부터 미지의 가진력을 산정하고 수치해석 및 구조실험의 검증을 통하여 콘크리트 슬래브의 미진동해석 및 제어를 실시하였다. 미진동제어 설계를 위한 구조물의 고유진동수는 25-30Hz 이상이 되는 것인 바람직하며 콘크리트 구조물에서의 감쇠가 3%-5%인 경우 가진력 진동성분의 1.5배 이상 되는 것이 바람직함을 밝혔다. This study is to develop a technique for micro-vibration analysis and control of concrete slabs to fulfil the vibration criteria for working environments. The proposed technique is for determining the unknown forces from accelerance of two concerned points and the micro-vibration analysis and control of concrete slabs are then validated by numerical model and structural tests. And it is recommended that the natural frequency of structures for micro-vibration control design should be above 25 Hz~30 Hz, and 1.5 times forcing frequency in case of 3~5% structural damping ratio of concrete structures.

Usefulness of Ultrasound in Acute Scrotal Trauma

Lho, Yong Soo,Park, Jeong Hee,Choi, young Chill,Jeon, Hae Jeong 건국대학교 의과학연구소 1993 건국의과학학술지 Vol.3 No.-

In the case of testis rupture, emergent surgical intervention is of great importance to preserve testicular function. We studied retrospectively the sonographic findings of testis rupture. In 15 patients with acute blunt scrotal trauma, scrotal ultrasound studies were used to make a decision whether the operation was needed. Of all 15 cases, ten cases were diagnosed as testis rupture and confirmed by operation. In two cases, there were no abnormalities. One case revealed epididymitis and One case demonstrated pampiniform plexus hematoma. One case was confirmed as spermatic cord hematoma. Ultrasound is valuable for differential diagnosis of testicular and extratesticular lesion such as epididymitis, scrotal fluid collection even if severe scrotal swelling is present. Ultrasound studies are very accurate in the evaluation of testis rupture. The suggestive findings of testis rupture are unequal irregular testicular size, ill defined margination and inhomogeneous testicular parenchymal echo pattern.