• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.6
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• pp.706-711
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• 2014

A low power 6-bit flash ADC that uses an input voltage range detection algorithm is described. An input voltage level detector circuit has been designed to overcome the disadvantages of the flash ADC which consume most of the dynamic power dissipation due to comparators array. In this work, four digital input voltage range detectors are employed and each input voltage range detector generates the specific clock signal only if the input voltage falls between two adjacent reference voltages applied to the detector. The specific clock signal generated by the detector is applied to turn the corresponding latched comparators on and the rest of the comparators off. This ADC consumes 68.82 mW with a single power supply of 1.2V and achieves 4.3 effective number of bits for input frequency up to 1 MHz at 500 MS/s. Therefore it results in 4.6 pJ/step of Figure of Merit (FoM). The chip is fabricated in 0.13-um CMOS process.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.12
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• pp.43-53
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• 2007

We have analyzed low current operation characteristics of a VCSEL transmitter operating at fixed Current over wide temperature range. Used 850 nm oxide VCSEL has low temperature dependence of the threshold current and $d^2I_{th}/dT^2$ is approximately $1.346\times10^{-4}mA/^{\circ}C^2$. We fixed on-current so that output power from the chip is 1 mW at $20^{\circ}C$ and investigated the turn-on, turn-off characteristics and eye-diagram of the 850 nm oxide VCSEL transmitter with varying ambient temperature and off-current. We measured rise time, fall time, extinction ratio and timing jitter by changing tile ambient temperature and off-current. With the fixed off-current of around $0.1\sim0.2mA$ lower than the lowest threshold current the transmitter successfully operated at 1.25 Gbps over a wide temperature range from $-20^{\circ}C$ to $80^{\circ}C$.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2006.11a
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• pp.301-305
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• 2006

An electrical bill is one of the various factors that influence on energy use of residents. This study focused on electrical bills and searched that whether electrical bills affect resident behavior of operating air conditioner and their controlled indoor climate. We surveyed two groups for field study ; the one is residents who live in a studio apartment in Seoul and they are charged for electric as energy consumption they used, and the other is residents who live in a university dormitory and they are not charged for their energy consumption. We measured how long they used the air conditioner for cooling, on/off temperature of air conditioner and room temperature for these two groups. Residents were interviewed about their cooling needs, decisions about when to turn on their air conditioner and so on. We found that dormitory group has much amount of time used the air conditioner than studio apartment group and there are differences of room temperature between two groups when they turn on or off air conditioner. The result shows that perception of money affects resident behavior of operating air conditioner and their acceptable thermal range.

• Journal of Power Electronics
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• v.18 no.1
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• pp.11-22
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• 2018

This paper presents a single switch, high step-up, non-isolated dc-dc converter suitable for renewable energy applications. The proposed converter is composed of a coupled inductor, a passive clamp circuit, a switched capacitor and voltage lift circuits. The passive clamp recovers the leakage inductance energy of the coupled inductor and limits the voltage spike on the switch. The configuration of the passive clamp and switched capacitor circuit increases the voltage gain. A wide continuous conduction mode (CCM) operation range, a low turn ratio for the coupled inductor, low voltage stress on the switch, switch turn on under almost zero current switching (ZCS), low voltage stress on the diodes, leakage inductance energy recovery, high efficiency and a high voltage gain without a large duty cycle are the benefits of this converter. The steady state operation of the converter in the continuous conduction mode (CCM) and discontinuous conduction mode (DCM) is discussed and analyzed. A 200W prototype converter with a 28V input and a 380V output voltage is implemented and tested to verify the theoretical analysis.

• Journal of the Semiconductor & Display Technology
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• v.14 no.4
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• pp.92-97
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• 2015

The purpose of this work is to support a solution of optimizing TMO (tone mapping operator). JPEG XT Profile A and C utilize Erik Reinhard TMO that works well in most cases, however, detailed information of a scene is lost in some cases. Reinhard TMO only calculates its coefficient to have tone-mapping curve from log-average luminance, and this lead to lose details of bright and dark area of scenes in turn. Thus, this paper proposes an enhancement of the default TMO for JPEG XT Profile C to optimize tone-mapping curve. Main idea is that we divide tone mapping curve into several ranges, and set reasonable parameters for each range. By the experimental results, the proposed scheme shows and obtains better performance within a dark scene, compared to the default Reinhard TMO.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.8
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• pp.727-731
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• 2000

This paper presents a new practical autopilot design approach to acceleration control for tail-controlled STT(Skid-to-Turn) missiles. The approach is novel in that the proposed parametric affine missile model adopts acceleration as th controlled output and considers the couplings between the forces as well as the moments and control fin deflections. The aerodynamic coefficients in the proposed model are expressed in a closed form with fittable parameters over the whole operating range. The parameters are fitted from aerodynamic coefficient look-up tables by the function approximation technique which is based on the combination of local parametric models through curve fitting using the corresponding influence functions. In this paper in order to employ the results of parametric affine modeling in the autopilot controller design we derived a parametric affine missile model and designed a feedback linearizing controller for the obtained model. Stability analysis for the overall closed loop sys-tem is provided considering the uncertainties arising from approximation errors. the validity of the proposed modeling and control approach is demonstrated through simulations for an STT missile.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.4
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• pp.383-390
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• 2014

This paper deals with novel soft-switching method for a bidirectional DC-DC converter in battery charging and discharging system. The proposed soft-switching method provides ZVS and ZCS at turn-on, and ZVS at turn-off of the switch in both charging and discharging operation modes. The soft switching condition can be obtained in wide load range, and provide low switching loss as well as low voltage spike at turn-off of the switch. Proposed method is analyzed in charging and discharging mode. Simulation and experimental results validate the usefulness of the proposed soft-switching method.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.654-656
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• 2002

The pole shape. turn-on angle. and turn-off angle are important design factors that largely influence Switched Reluctance Motor' s performance when designing a switched reluctance motor. These design factors must be considered simultaneously because an independent factor restricts the improvement of the switched reluctance motor' s performance. After performing the analysis using nonlinear same characteristic finite element method that contains a operating circuit, the influence upon the torque characteristics was analyzed by the pole shape and the angles. This paper presents the most suitable design value according to input conditions and various speeds. Especially.the most suitable angles were derived from the voltage equation. and an effective design range is showed from the angles.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.338-339
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• 2011

본 논문에서는 SRC를 이용한 고효율 차량탑재형 충전기를 제안한다. 제안한 컨버터는 앞단의 부스트컨버터가 역률보상과 동시에 배터리의 전압 전류 제어를 수행하고 후단의 SRC를 고정듀티와 고정주파수로 동작시켜 전 부하영역에서 스위치와 다이오드의 ZCS 턴온 턴오프가 가능하다. 3.3kW의 시작품으로 부터 CC-CV 충전을 통한 제안한 방식의 타당성을 검증한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.459-464
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• 2004

In this paper, an autonomous navigation system for autonomous guided vehicles (AGVs) operated in an automated container terminal is designed. The navigation system is based on the sensors detecting the range and bearing. The navigation algorithm used is an interacting multiple model (IMM) algorithm to detect other AGVs and avoid other obstacles using informations obtained from multiple sensors. As models to detect other AGVs (or obstacles), two kinematic models are derived： Constant velocity model for linear motion and constant speed turn model for curvilinear motion. For constant speed turn model, an unscented Kalman filter (UKF) is used because of drawbacks of the extended Kalman filter (EKF) in nonlinear system. The suggested algorithm reduces the root mean squares error for linear motions, while it can rapidly detect possible turning motions.