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Design of ESD Protection Circuits for High-Frequency Integrated Circuits (고주파 집적회로를 위한 ESD 보호회로 설계)

  • Kim, Seok;Kwon, Kee-Won;Chun, Jung-Hoon
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.47 no.8
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    • pp.36-46
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    • 2010
  • In multi-GHz RF ICs and high-speed digital interfaces, ESD protection devices introduce considerable parasitic capacitance and resistance to inputs and outputs, thereby degrading the RF performance, such as input/output matching, gain, and noise figure. In this paper, the impact of ESD protection devices on the performance of RF ICs is investigated and design methodologies to minimize this impact are discussed. With RF and ESD test results, the 'RF/ESD co-design' method is discussed and compared to the conventional RF ESD protection method which focuses on minimizing the device size.

Development of the Digital AVR for Ship Generator (선박발전기용 디지털 AVR 개발)

  • Kim, T.W.;Kim, S.W.;Lee, S.B.;Song, S.H.;Lee, S.J.;Kim, M.C.;Lee, S.D.
    • Proceedings of the KIEE Conference
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    • 2003.07b
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    • pp.828-830
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    • 2003
  • AVR은 동기발전기의 출력전압을 부하변동에 관계없이 일정하게 제어하며 발전기 및 시스템 보호를 위한 각 종 제어 알고리즘을 구비하고 있다. 종래의 아나로그타입 AVR은 제어설정이 불편하고 제어신뢰성이 떨어지기 때문에 점차 디지털 타입으로 교체되고 있다. 본 연구는 선박발전기에 적용하기 위한 디지털 AVR 개발에 관한 것이다. TI사의 TMS320LF2407 CPU를 사용하여 제어 H/W를 개발했으며, 과여자/저여자제어, Droop제어, 무부하/역률제어 등 다양한 제어기능을 S/W로 구비하여 부하에 따른 적용의 유연성을 높였다. 그리고 전력회로는 IGBT를 사용하여 고속 스위칭 제어함으로써 SCR 방식에 비해 제어 속응성을 개선하였다. 개발 된 제품은 AVR, 직류전원공급장치 및 부하나 계통의 사고시 보호를 위한 전류부스트(CBS)기능을 포함하고 있다.

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Residual Stress Prediction and Hardness Evaluation within Cross Ball Grooved Inner Race by Cold Upsetting Process (냉간 업셋팅 공정에 의한 경사형 볼 그루브를 갖는 내륜의 잔류응력 예측 및 경도 평가)

  • T.W. Ku
    • Transactions of Materials Processing
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    • v.32 no.4
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    • pp.180-190
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    • 2023
  • This study deals with residual stress prediction and hardness evaluation within cross ball grooved inner race fabricated by cold upsetting process consisted of upsetting and ejection steps. A raw workpiece material of AISI 5120H (SCr420H) is first spheroidized and annealed, then phosphophyllite coated to form solid lubricant layer on its outer surface. To investigate influences of the heat treatment, uni-axial compression tests and Vickers micro-hardness measurements are conducted. Three-dimensional elasto-plastic FE simulations on the upsetting step and the ejection one are performed to visualize the residual stress and the ductile (plastic deformation) damage. External feature of the fabricated inner race is fully captured by using an optical 3D scanner, and the micro-hardness is measured on internal cross-sections. Consequently, the dimensional compatibility between the simulated inner race and the fabricated one is ensured with a difference of under 0.243mm that satisfied permissible error range of ±0.50mm on the grooved surface, and the predicted residual stress is verified to have similar distribution tendency with the measured Vickers micro-hardness.

3-Phase Power Quality Disturbance Generator with Phase Jump Function (위상급변 기능을 갖는 3상 전력품질 외란발생기)

  • Lee, B.C.;Choi, S.H.;Paeng, S.H.;Park, S.D.;Choi, N.S.;Kim, I.D.;Chun, T.W.;Kim, H.G.;Nho, E.C.
    • The Transactions of the Korean Institute of Power Electronics
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    • v.11 no.5
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    • pp.463-470
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    • 2006
  • This paper deals with a new 3-phase power quality disturbance generator. The proposed generator can provide phase jump as well as voltage sag, swell, outage, unbalance, and over and under voltage. The operating principle of the generator is described in each mode of disturbance. The magnitude of the phase jump is analysed and it is found that the magnitude is the function of the turn-ratios of the transformers consisting the generator. The scheme has simple structure compared with the conventional one, and the major components of the proposed scheme are SCR thyristor and transformer, which guarantees high reliability and cost-effective implementation of the generator. Furthermore, high efficiency can be obtained because there is no PWM switching of the semiconductor devices, and it is easy to control the system. Simulations are carried out to confirm the operation in each disturbance mode, and experiments has been done with 5kVA power rating. The usefulness of the proposed scheme is verified through simulation and experimental results. It is expected that the scheme can be applied to the performance test of the custom power devices such as UPS, DVR, DSTATCOM, and SSTS with cost-effective system.

Renal Toxicity of High-dose Intravenous Immunoglobulin in Children with Kawasaki Disease and Idiopathic Thrombocytopenic Purpura (가와사끼병과 특발성 혈소판 감소성 자반증 환아에서 고용량 정주용 면역글로불린의 신독성 유무)

  • Jung Ji Ah;Kim Hye Soon;Seo Jeong Wan;Lee Seung Joo
    • Childhood Kidney Diseases
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    • v.2 no.2
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    • pp.133-137
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    • 1998
  • Purpose : To investigate renal toxicity of high-dose intravenous immunoglobulin(IVIG) in children with Kawasaki disease and idiopathic thrombocytopenic purpura. Methods : 23 children with Kawasaki disease and 7 children with idiopathic thrombocytopenic purpura who were treated with high-dose IVIG(2 g/kg) were evaluated for the change of urine output, blood urea nitrogen(BUN), serum creatinine(Scr), creatinine clearance(Ccr), tubular reabsorption of phosphorus(TRP), fractional excretion of sodium(FENa), 24hour urine ${\beta}_2$-microglobulin/creatinine(${\beta}_{2}MG/cr$) ratio and urine microalbumin/creatinine(MA/cr) ratio at post-IVIG 1 and 3 day. Results : There was no significant change of urine output, BUN, Scr, Ccr, TRP, 24hour urine ${\beta}_{2}MG/cr$ and MA/cr ratio after high-dose IVIG treatment. Transient increase of FENa at post-IVIG 1 day was the only significant change. Conclusion : There was no significant renal toxicity of high-dose IVIG in children with Kawasaki disease and idiopathic thrombocytopenic purpura who had normal renal function.

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Semantische Unbestimmtheit der Skalaradjektiven (척도형용사의 의미적 불확정성에 대한 연구)

  • Chung Dong-Gyu
    • Koreanishche Zeitschrift fur Deutsche Sprachwissenschaft
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    • v.10
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    • pp.277-296
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    • 2004
  • Ein sprachlicher Ausdruck ist in verschiedenen Situationen in einer Vielzahl unterschiedlicher Lesarten oder $Pr\"{a}zisierungen$ verwendbar, und zwar mil dom Grad an $Pr\"{a}zision$, der den jeweiligen kormmunikativen Erfordernissen angemessen ist. Sokommt Vagheit/$Ambiguit\"{a}t$ in sprachlichen Ausdrucken fast $durchg\"{a}ngig$ vol. In der vorliegenden Albeit wird die $M\"{o}glichkeit$ der semantischen $\"{U}bersetzung$ der Skalaradjektiven($gro{\ss}$, klein, $hei{\ss}$, kalt, schwer, leicht, schnell, langsam usw.) untersucht, die eigentlich die Vagheit als eine der konstitutiven Eigenschaften haben. Den Schwerpunkt $daf\"{u}r$ bildet die semantische Analyse $\"{u}ber$ die Graduierbarkeit und Vergleichbarkeit der Positivformen der Adjektiven, die vol allem M.J.Cresswell 1976 in seiner Albeit formuliert hat. V(pos) is the function $\eta$ in $D_{{\lll}{0,1}>,<{0,1}{\gg}.{\ll}{0,1,1},>,<{0.1}{\ggg}$ such that where ${\xi}{\in}D_{{\ll}{0,1,1},><{0,1}{\gg}$,$\eta({\xi})$ is the following function: For any ${\omega}{\in}D_{<0,1>$and a ${\in}D_1$ and w$\in$W, w${\in}{\eta}({\xi})({\omega})$(a) iff w ${\in}{\omega}$(a) and there is exactly one b such that ${\xi}({\omega})$(a,b); and for that b, b=$\gg$(for some > and u ${\in}{ \scr}{Z}(>))$ and u is toward the top of the scale determined by > when restricted to those v such that for some c, w${\in} {\xi}({\omega})$$(c,{\;} and w${\in}{\omega}(c)$. (Cresswell, 1976: 272) Obwohl sein Verfahren anhnd von dem semantischen Symbol eine methodische und theoretische $Ad\"{a}quatheit$ erf\"{u}llt$, bleibt der Vergleichwert noch unterspezifiziert. Fur die Behandlung dieser semantischen Unterspezifikation ist eine neue Semantik erforderlich, die den Wahrheitwert fur die $Zugeh\"{o}rigkeitsgrade$ der Skalaradjektive $einschlie{\ss}t$.

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The Effect of HCl Gas on Selective Catalytic Reduction of Nitrogen Oxide (질소산화물의 선택적 환원 제거시 염화수소기체가 촉매에 미치는 영향)

  • Choung, Jin-Woo;Choi, Kwang-Ho;Seong, Hee-Je;Chai, Ho-Jung;Nam, In-Sik
    • Journal of Korean Society of Environmental Engineers
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    • v.22 no.4
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    • pp.609-617
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    • 2000
  • This study is aimed at investigating an effect of HCl gas on selective reduction of NOx over a CuHM and $V_2O_5-WO_3/TiO_2$ catalyst. SCR process is the most effective method to remove NOx, but catalyst can be deactivated by the acidic gas such as HCl gas which is also included in flue gas from the incinerator. In dry condition of flue gas, the CuHM catalyst treated by HCl gas has shown higher NO removal activity than the fresh catalyst. The activity of the catalyst can be restored by treating at $500^{\circ}C$. On the contrary. $V_2O_5-WO_3/TiO_2$ catalyst is obviously deactivated by HCl and the deactivation increases in proportion to the concentration of HCl gas. The deactivated catalyst is not restored to it's original activity by heat treatment for regeneration. In wet flue gas stream, the CuHM catalyst has shown lower activity than fresh catalyst and $V_2O_5-WO_3/TiO_2$ catalyst was severely deactivated by HCl treatment. The activity loss of catalysts are mainly due to the decrease of Br$\ddot{o}$nsted acid site on the catalyst surface by $NH_3$ TPD. The change of BET surface area of CuHM catalyst after the reaction isn't observed but $V_2O_5-WO_3/TiO_2$ catalyst is observed. The amount of $Cu^{{+}{+}}$ and $V_2O_5$ is decreased after the reaction. From these results, it is expected that CuHM catalyst should be better than $V_2O_5-WO_3/TiO_2$ catalyst for its application to the incineration of flue gas.

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Development of the integrated unit module large-capacity inverter arc welding machines and application for butt welding of thick weldments (단위 모듈 집적형 대용량 인버터 아크용접기의 개발과 후판 맞대기 용접에의 적용)

  • Shin, Hee-Seop;Jung, Yun-Ho;Son, Chang-Hee;Lim, Sung-Ryong;Jung, Soo-Wook;Yoon, Hye-Won;So, Soon-Sam;Cho, Sang-Myoung
    • Proceedings of the KWS Conference
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    • 2009.11a
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    • pp.24-24
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    • 2009
  • 현재 조선소를 비롯하여 각종 산업 전반적으로 기존의 SCR 용접기를 대체하여 용접품질이 우수한 인버터 용접기가 널리 사용되고 있는 실정이다. 그러나 기존 인버터 용접기의 전원은 Mono 타입으로 이루어져 있어 대용량 인버터 용접기의 경우 대용량 스위칭 소자가 요구되어 제조원가가 높다. 그리고 문제 발생 시 용접기의 사용이 불가능하게 된다. 개발된 단위모듈을 병렬로 연결하여 대용량 용접기를 구성하게 되면 제조원가를 절감할 수 있으며 병렬로 연결되어 단위 모듈에 문제가 발생하여도 계속적인 사용이 가능하고, 주 회로를 작은 용량으로 분산시켜 전력을 제어하므로 높은 에너지 효율을 가지게 된다. 또한 인버터 용접기의 가장 중요한 성능인 스위칭 주파수에 있어서도 기존의 인버터 용접기는 20kHz의 스위칭 주파수를 가지지만 본 기술은 낮은 전력을 병렬로 연결하여 대용량을 동시에 제어가능 하므로 약 70kHz의 고속제어가 가능하다. 본 연구에서는 개발된 용량 170A단위모듈을 병렬로 연결하여 단위모듈 집적형 인버터 아크용접기 510A, 680A급의 부하테스트 실시 및 기본출력특성에 대하여 실험하였으며, GMAW에서 ${\Phi}1.6$ 솔리드 와이어를 이용하여 두께 20t의 후판 맞대기 용접에 적용실험을 실시하였다. 그 결과 모든 전류영역에서의 부하특성 및 출력특성이 양호하게 나타났으며, 후판 맞대기 용접에서는 SAW에 버금가는 생산성과 용접특성을 얻을 수 있었다.

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A Study on Protection Coordination Algorithm for Separating Fault Section in LVDC Distribution System (LVDC 배전계통에 있어서 사고구간분리 보호협조 알고리즘에 관한 연구)

  • Kang, Min-Kwan;Lee, Hu-Dong;Tae, Dong-Hyun;Rho, Dae-Seok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.1
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    • pp.768-776
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    • 2021
  • Current protection-coordination methods use the reverse time characteristics of the T-C curve, which is not effective for a LVDC distribution system because the protective operation time of converters and DC circuit breakers is much faster than AC protection devices. Therefore, an algorithm is proposed for fault-section isolation using the fault current slope to minimize the blackout region and coordinate between converters and protection devices in a rapid and accurate manner. The method deals with the slope characteristics of a fault current, which may depend on the fault location in an LVDC distribution system. Thus, an LVDC distribution system can be operated in a stable manner by isolating the fault section selectively before the shutdown of the main converter using slope characteristics, which change in proportion to the line impedance and fault location. A 1.5-kV LVDC distribution system was modeled to verify the effectiveness of the proposed algorithm using PSCAD/EMTDC. The system is composed of a distribution substation, LVDC converter, and distribution lines. The simulation results confirm that the proposed algorithm is a useful tool for minimizing the fault section in an LVDC distribution system.

Triptolide-induced Transrepression of IL-8 NF-${\kappa}B$ in Lung Epithelial Cells (폐상피세포에서 Triptolide에 의한 NF-${\kappa}B$ 의존성 IL-8 유전자 전사활성 억제기전)

  • Jee, Young-Koo;Kim, Yoon-Seup;Yun, Se-Young;Kim, Yong-Ho;Choi, Eun-Kyoung;Park, Jae-Seuk;Kim, Keu-Youl;Chea, Gi-Nam;Kwak, Sahng-June;Lee, Kye-Young
    • Tuberculosis and Respiratory Diseases
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    • v.50 no.1
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    • pp.52-66
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    • 2001
  • Background : NF-${\kappa}B$ is the most important transcriptional factor in IL-8 gene expression. Triptolide is a new compound that recently has been shown to inhibit NF-${\kappa}B$ activation. The purpose of this study is to investigate how triptolide inhibits NF-${\kappa}B$-dependent IL-8 gene transcription in lung epithelial cells and to pilot the potential for the clinical application of triptolide in inflammatory lung diseases. Methods : A549 cells were used and triptolide was provided from Pharmagenesis Company (Palo Alto, CA). In order to examine NF-${\kappa}B$-dependent IL-8 transcriptional activity, we established stable A549 IL-8-NF-${\kappa}B$-luc. cells and performed luciferase assays. IL-8 gene expression was measured by RT-PCR and ELISA. A Western blot was done for the study of $I{\kappa}B{\alpha}$ degradation and an electromobility shift assay was done to analyze NF-${\kappa}B$ DNA binding. p65 specific transactivation was analyzed by a cotransfection study using a Gal4-p65 fusion protein expression system. To investigate the involvement of transcriptional coactivators, we perfomed a transfection study with CBP and SRC-1 expression vectors. Results : We observed that triptolide significantly suppresses NF-${\kappa}B$-dependent IL-8 transcriptional activity induced by IL-$1{\beta}$ and PMA. RT-PCR showed that triptolide represses both IL-$1{\beta}$ and PMA-induced IL-8 mRNA expression and ELISA confirmed this triptolide-mediated IL-8 suppression at the protein level. However, triptolide did not affect $I{\kappa}B{\alpha}$ degradation and NF-$_{\kappa}B$ DNA binding. In a p65-specific transactivation study, triptolide significantly suppressed Gal4-p65T Al and Gal4-p65T A2 activity suggesting that triptolide inhibits NF-${\kappa}B$ activation by inhibiting p65 transactivation. However, this triptolide-mediated inhibition of p65 transactivation was not rescued by the overexpression of CBP or SRC-1, thereby excluding the role of transcriptional coactivators. Conclusions : Triptolide is a new compound that inhibits NF-${\kappa}B$-dependent IL-8 transcriptional activation by inhibiting p65 transactivation, but not by an $I{\kappa}B{\alpha}$-dependent mechanism. This suggests that triptolide may have a therapeutic potential for inflammatory lung diseases.

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