• 전자공학회논문지
• /
• 제54권5호
• /
• pp.11-16
• /
• 2017

RF MOSFET에서 관찰된 입력 저항의 주파수 종속 특성이 단순화된 입력 등가회로로부터 유도된 pole과 zero 주파수 수식을 사용하여 자세히 분석되었다. 이러한 이론적 분석을 사용하여 저주파에서 입력저항의 감소현상이 포화영역에서 소스와 pinch-off 영역 사이의 채널저항으로부터 발생되는 것을 발견하였다. 이와 같이 저주파에서 입력저항이 감소하는 채널 저항 효과는 채널저항을 변화시키면서 소신호 등가회로 모델링을 수행하여 물리적으로 입증되었다.

• 대한전자공학회논문지
• /
• 제13권6호
• /
• pp.7-11
• /
• 1976

연산증폭기를 이용한 전압안정부저항회로를 제안하였으며, 전입력전압범위에 걸쳐서 회로를 해석하였다. 부저항영역에서 이 v-i특성이 2가지 구분된 요인에 의해서 이루어짐을 밝혔고, 이 개념에 의해서 역 v-i특성의 꼭지점을 해석하였다. 제안된 회로를 실험하여 얻은 입력 v-i특성의 직선성은 대단히 양호하였으며, 이들의 부저항치는 전압범위 ±1∼±5V에서 -86∼833Ω였다. 그리고 전입력전압범위에서 v-i특성을 검토했다. A voltage-stable negative resistance circuit with operational amplifier is proposed, and circuit analysis is given all the input voltage range. The behavior of the v-i characteristics in the nogative resistance region is devided into two causes, and top points in the input v-i characteristics of the circuit is analyzed with them. Experimental results of the v-i characteristics of the proposed circuit has a good linearity in the negative region with negative resistance, -86Ω∼-833Ω for the input voltage, ± 1∼± 5 colts. The v-i characteristics of the circuit in all the input voltage range is discussed.

• Journal of Welding and Joining
• /
• 제22권5호
• /
• pp.58-64
• /
• 2004

Although leakage at a low carbon steel pipe made by electrical resistance welding (ERW) was reported due to grooving corrosion, the cause for the corrosion has not yet been cleared. In order to clarify the main cause, failure analysis on the leaked pipe was carried out, followed by metallographic investigation and corrosion test for the various ERW pipe made with different welding heat input. The microstructure, particularly inclusion content, of the weldment is dependant on the welding heat input applied. For an improper low heat input, the amount of inclusion at the weld was high. High inclusion content accelerated grooving corrosion at the weld. It is therefore that welding heat input should be controlled based on the carbon content of the pipe in order to improve the corrosion resistance of the ERW pipe.

• 한국가시화정보학회지
• /
• 제17권1호
• /
• pp.10-18
• /
• 2019

In this study, the temperature behavior of Pulsating Heat Pipe (PHP) according to the diameter change were studied by limiting the diameter change to only the evaporator. To investigate operation of PHP in various heat input, heat input power was increased from 10 to 120 W. The results show operation can be divided into 3 regimes by temperature behavior. Thermal resistance was increased before start-up and decreased with increasing heat input. At 110 W heat input, thermal conductivity of 2 mm PHP was 8 .times higher compare to thermal conductivity of copper. Further, to investigate details of temperature behavior in higher heat input, FFT analysis was conducted. Based on the results, when the deviation of peak frequency in each section is lowest, the thermal resistance has lowest value.

• Corrosion Science and Technology
• /
• 제16권6호
• /
• pp.278-284
• /
• 2017

The effects of TIG welding and post-treatment procedures on the microstructure and the pitting corrosion resistance of welded lean duplex stainless steel S82441 were investigated. Autogenous TIG welding was used with different amounts of heat input and shielding gases such as Ar, and mixtures of $Ar-N_2$ and Ar-He. The addition of 5% to 15% of nitrogen to argon practically did not affect the level of the pitting corrosion resistance. However, the application of gas mixtures (50% Ar + 50% He) resulted in a significant decrease in pitting corrosion resistance. We found that increased current (200 A and 250 A) led to lower values of CPT of welds compared with welds obtained with 50 A, 100 A and 150 A. In addition, the removal of the weld surface layer (0.2 ~ 0.3 mm thickness) in most cases not only resulted in a significant increase in resistance to the pitting corrosion but also post-treatment of weld, implying that corrosion resistance depended on factors such as surface roughness or the presence of undesirable oxides.

• 지식경영연구
• /
• 제16권4호
• /
• pp.191-213
• /
• 2015

With the advancement of virtual reality technology, virtual reality contents and devices are being competitively released. This research deals with an early stage adoption model of a motion-sensing input device which enhances the user experience of these virtual reality contents and devices. In contrast to the previous research on the adoption or resistance of innovative products, this work compares and analyzes the antecedents in MIR(Model of Innovation Resistance) of resistance-perspective as well as those in UTAUT2(Extended Unified Theory of Acceptance and Use of Technology) and IDT(Innovation Diffusion Theory) of adoption-perspective, and suggests a resistance-incorporated adoption model from a new viewpoint. The analysis of questionnaire data indicates the following results: Performance expectancy, effort expectancy, price value, hedonic motivation in UTAUT2 and visibility in IDT have a significant negative influence on innovation resistance. Compatibility in IDT and MIR exerts a positive influence on perceived value. Social influence and hedonic motivation in UTAUT2 positively relates to perceived value. Higher innovation resistance results in lower perceived value, with innovation resistance and perceived value negatively and positively affecting intention to use, respectively.

• 한국군사과학기술학회지
• /
• 제4권1호
• /
• pp.264-273
• /
• 2001

The conjugate heat transfer from a protruding module in a horizontal channel with a variation of air temperature is experimentally investigated. It is an aim of this study is to estimate temperature difference between a module and air. This study is performed with a variation of parameters that are air temperatures($T_i,=25^{\circ}C{\sim}55^{\circ}C),$ thermal resistance($R_c=158 K/W),$ air velocities ( 4V_i=0.1$ m/s~l.5 m/s ), and input power (Q=3 W, 7 W ). The results show that as the thermal resistance increases, the effect of air temperatures are decreased. And input power was most effective parameter on the temperature difference between a module and air.

• 한국세라믹학회지
• /
• 제26권1호
• /
• pp.21-30
• /
• 1989

Titanium Nitride (TiN) was deposited onto the SKH9 tool steels by chemical vapor deposition (CVD) using a gaseous mixture of TiCl4, N2, and H2. The effects of the deposition temperature and input gas composition on the deposition rate, microstructure, preferred orientation, microhardness and wear resistance of TiN deposits were studied. The experimental results showed that the TiN deposition is thermally activated process with an apparent activation energy of about 27Kcal/mole in the temperature range between 1200$^{\circ}$K and 1400$^{\circ}$K. As H2/N2 gas input ratio increased, the deposition rate increased, showed maximum at H2/N2 gas input ratio of 1.5 and then decreased. Mechanical properties such as microhardness and wear resistance have close relation with the microstructure and preferred orientation of TiN deposits. It is suggested that the equiaxed structure with random orientation increases the microhardness and wear resistance of TiN deposits.

• 전자공학회논문지
• /
• 제53권12호
• /
• pp.15-19
• /
• 2016

매우 큰 사이즈를 가진 multi-finger RF MOSFET의 $S_{11}$-parameter에서 스미스차트의 저항 circle 라인을 벗어나는 kink 현상의 게이트 바이어스 종속 특성이 관찰되었다. 이러한 바이어스 종속성은 $S_{11}$-parameter의 크기와 위상, 입력저항, 입력 커패시턴스의 주파수 응답곡선을 측정하여 최초로 분석되었다. 그 결과 입력 커패시턴스의 크기와 입력저항의 dominant pole과 zero 주파수에 의해 $V_{gs}$ 종속 kink 현상이 크게 변하는 것을 알 수 있다. $V_{gs}=0V$일 때 매우 적은 $S_{11}$-parameter 위상차와 입력저항의 높은 pole 주파수에 의해 고주파영역에서 kink 현상이 나타난다. 하지만 $V_{gs}$가 높아지면 $S_{11}$-parameter 위상차가 크게 증가하고 pole 주파수가 낮아져 저주파영역에서 kink 현상이 발생하게 된다.

• 전자공학회논문지
• /
• 제51권12호
• /
• pp.59-65
• /
• 2014

다양한 게이트 핑거 수(Nf)의 MOSFET에 대한 두 종류의 입력 저항이 $S_{11}$-parameter와 $Z_{11}$-parameter으로부터 변환 되어 저주파 영역에서 측정되었다. 본 연구에서 사용된 $Nf{\leq}64$의 범위에서 $S_{11}$-parameter로부터 추출된 1/Nf 종속 입력저항은 $Z_{11}$-parameter로부터 추출된 입력 저항보다 훨씬 낮은 값을 보여주며, 이러한 1/Nf 종속성은 MOSFET의 등가회로로부터 유도된 Nf 종속 비선형 방정식으로부터 이론적으로 증명하였다.