• Journal of Radiation Protection and Research
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• 제48권3호
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• pp.124-130
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• 2023

Background: When bipolar junction transistors (BJTs) are used as switches, their switching characteristics can be deteriorated because the recombination time of the minority carriers is long during turn-off transient. When BJTs operate as low frequency switches, the power dissipation in the on-state is large. However, when BJTs operate as high frequency switches, the power dissipation during switching transients increases rapidly. Materials and Methods: When silicon (Si) BJTs are irradiated by fast neutrons, defects occur in the Si bulk, shortening the lifetime of the minority carriers. Fast neutron irradiation mainly creates displacement damage in the Si bulk rather than a total ionization dose effect. Defects caused by fast neutron irradiation shorten the lifetime of minority carriers of BJTs. Furthermore, these defects change the switching characteristics of BJTs. Results and Discussion: In this study, experimental results on the switching characteristics of a pnp Si BJT before and after fast neutron irradiation are presented. The results show that the switching characteristics are improved by fast neutron irradiation, but power dissipation in the on-state is large when the fast neutrons are irradiated excessively. Conclusion: The switching characteristics of a pnp Si BJT were improved by fast neutron irradiation.

• Nuclear Engineering and Technology
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• 제55권9호
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• pp.3334-3341
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• 2023

We studied the irradiation effects of fast neutron generated by a 30 MeV cyclotron on the electrical and switching characteristics of NPT-IGBT devices. Fast neutron fluence ranges from 2.7 × 10⁹ to 1.82 × 10¹³ n/cm². Electrical characteristics of the IGBT device such as I-V, forward voltage drop and additionally switching characteristics of turn-on and -off were measured. As the neutron fluence increased, the device's threshold voltage decreased, the forward voltage drop increased significantly, and the turn-on and turn-off time became faster. In particular, the delay time of turn-on switching was improved by about 35% to a maximum of about 39.68 ns, and that of turn-off switching was also reduced by about 40%-84.89 ns, showing a faster switching.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.14-16
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• 2009

Surface driven switching of the liquid crystal bulk arising from the coupling between an applied electric field and a polarized state of a nematic liquid crystal, both localized at the substrate surface, is reported. Fast switching is demonstrated in a hybrid aligned nematic cell with a fringe electric field generated by comb-like electrode structure.

• Nuclear Engineering and Technology
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• 제49권1호
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• pp.209-215
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• 2017

Fast neutron irradiation was used to improve the switching speed of a 600-V nonpunch-through insulated gate bipolar transistor. Fast neutron irradiation was carried out at 30-MeV energy in doses of $1{\times}10^8n/cm^2$, $1{\times}10^9n/cm^2$, $1{\times}10^{10}n/cm^2$, and $1{\times}10^{11}n/cm^2$. Electrical characteristics such as current-voltage, forward on-state voltage drop, and switching speed of the device were analyzed and compared with those prior to irradiation. The on-state voltage drop of the initial devices prior to irradiation was 2.08 V, which increased to 2.10 V, 2.20 V, 2.3 V, and 2.4 V, respectively, depending on the irradiation dose. This effect arises because of the lattice defects generated by the fast neutrons. In particular, the turnoff delay time was reduced to 92 nanoseconds, 45% of that prior to irradiation, which means there is a substantial improvement in the switching speed of the device.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 춘계종합학술대회
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• pp.197-200
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• 2001

최근의 확산대역 통신 방식에 사용되는 주파수 합성기는 주파수 스위칭 시간이 중요한 요소가 되고 있다. FH-SS(Frequency Hopping Spread Spectrum) 송수신기에서 고속 주파수 합성기 설계는 채널 효율을 높이기 위해 매우 중요하다. 본 논문에서는 기존 PLL방식에 직접 접근 주파수 합성 (DDS) 방식을 응용하여 1 $\mu\textrm{s}$ 이하의 스위칭 시간을 갖는 고속 주파수 합성기를 설계하고, 이를 2.4GHz 대리의FH-SS 송수신기에 적용하여 시뮬레이션 결과 20% 이상의 채널 효율 개선 효과를 얻었다.

• 대한전자공학회논문지SD
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• 제46권7호
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• pp.39-46
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• 2009

본 논문에서는 LED 백라이트를 위한 고속 스위칭 전류-펄스 드라이버(Current-Pulse Driver)를 제안하였다. 제안한 전류-펄스 드라이버는 드레인 정규화 전류미러(Regulated Drain Current Mirror : RD-CM)[1]와 고전압 NMOS 트랜지스터(High-Voltage NMOS Transistor : HV-NMOS)로 구성되었다. 동적 gain-boosting 앰프(Dynamic Gain-Boosting Amplifier : DGB-AMP)를 사용하여 전류-펄스 스위칭 응답속도를 향상시켰다. 출력 전류-펄스 스위치가 꺼졌을 때, RD-CM의 HV-NMOS 게이트 커패시턴스에 충전된 전하가 방전되지 않기 때문에 스위치가 다시 켜졌을 때, HV-NMOS 게이트 커패시턴스를 다시 충전할 필요가 없다. 제안한 전류-펄스 드라이버에서는 게이트 커패시턴스의 반복적인 충 방전 시간을 제거함으로써 전류-펄스 스위칭 동작을 고속으로 하도록 하였다. 검증을 위하여 SV/40V 0.5um BCD 공정으로 칩을 제작하였다. 제안한 전류-펄스 드라이버의 스위칭 지연시간을 기존 드라이버에서의 700ns에서 360ns로 줄일 수 있었다.

• 대한임베디드공학회논문지
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• 제5권3호
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• pp.128-135
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• 2010

Recently complexity of embedded software cause to be used real-time operating system (RTOS) to implement various functions in the embedded system. And also, according to requirement of complex functions in embedded systems, the number as well as complexity of tasks get increased continuously. In case that many tasks collaborated in a microprocessor, context switching time between tasks is a overhead waisting a CPU resource. Therefore the time of task context switching is an important factor that affects performance of RTOS. In this paper, we concentrate on the improvement of task context switch for reducing overhead and achieving fast response time in RTOS. To achieve these goal, we suggest multiple register files and task context switching algorithm. By reducing the context switch overhead, we try to ease scheduling and assure fast response times in multitasking environment. As a result, the context switch overhead decreased by 8~16% depend on the number of register files, and some task set which are not schedulable with single register file are schedulable due to that decrease with multiple register files.

• Journal of the Optical Society of Korea
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• 제19권3호
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• pp.260-264
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• 2015

We propose a negative liquid crystal (n-LC) cell with parallel patterned electrodes for high transmittance and fast response. The proposed cell has higher transmittance and shorter response time than a conventional fringe-field switching cell using n-LCs, because the proposed cell does not have transmittance dips and does have a thinner LC layer.

• Journal of Information Display
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• 제10권1호
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• pp.16-18
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• 2009

A three-terminal hybrid-aligned nematic liquid crystal (3T-HAN LC) cell capable of fast turn-off switching is proposed in this paper. By employing the relaxation process initiated by an electric-field pulse, a fast turn-off time of less than 1 ms can be obtained through optically hidden relaxation. A low operating voltage and high transmittance were confirmed through simulations and experiments.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.194-195
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• 2002

We report a fast-switching polymer-stabilized bend nematic (PSBN) device. The morphology study reveal a templated polymer networks captures the orientation of the field deformed nematic host.