• Journal of Microbiology and Biotechnology
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• 제3권3호
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• pp.146-155
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• 1993

A DNA fragment from an alkali-tolerent Bacillus sp., conferring strong promoter activity, was subcloned into the promoter probe plasmid pPL703 and the nucleotide sequence of this promoter region was determined. The sequence analysis suggested that this highly efficient promoter region containing the complex clustered promoters comprised three kinds of promoters (P1, P2 and P3), which are transcribed by $\sigma^B (formerly \sigma^{37}), \sigma^E(formerly \sigma^{29}) and \sigma^A (formerly \sigma^{43})$ RNA polymerase holoenzymes which play major rules at the onset of endospore formation, during sporulation and at the vegetative phase of growth, respectively. S1 nuclease mapping experiments showed that all three promoters had staggered transcription initiation points. The results of chloramphenicol acetyltransferase assay after the subcloning experiments also indicated that the expression of these clustered promoters was correlated with the programs of growth and endospore development. Promoter P1, P2 and P3 were preceded by 75% AT, 79% AT and 81% AT regions, respectively, and a partial deletion of AT-rich region prevented transcription from promoter P1 in vivo. Two sets of 5 -AGTGTT-3 sequences and inverted repeat sequences located around the promoter P1 were speculated as the possible cis acting sites for the catabolite repression in B. subtilis. In vivo transcripts from these sequence regions may be able to form a secondary structure, however, the possibility that a regulatory protein induced by the excess amount of glucose could be bound to such a domain for crucial action remains to be determined.

• 한국광학회지
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• 제15권1호
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• pp.79-85
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• 2004

후면의 석영면에 위상 패턴을 형성하여 투과율 조절을 구현한 포토마스크에 대해 보고한다. 위상 패턴의 크기와 패턴 조밀도에 따른 조명 동공의 형태 변화에 관한 이론적 결과와 투과율 조절 포토마스크를 사용한 웨이퍼 상 CD(critical dimension) 균일도 개선에 관한 실험적 결과에 대해 기술한다. 투과율 조절을 위한 위상 패턴은 패턴이 형성되지 않은 영역에 대해 180$^{\circ}$의 상대적 위상을 갖도록 석영면을 식각한 콘택홀 형태의 패턴을 사용하였다. 콘택홀 패턴의 크기가 작을수록 본래의 조명동공 형태를 유지하게 되며, 동일한 패턴 조밀도에서 더욱 큰 노광 광세기 저하가 일어남을 알 수 있었다. 패턴 조밀도를 위치별로 변화시켜 CD균일도 개선에 적합한 투과율 분포를 포토마스크 후면에 형성하였다. 투과율 조절 포토마스크를 140nm 디자인 롤을 갖고 있는 DRAM(Dynamic Random Access Memory)의 한 주요 레이어에 적용하여 CD 균일도를 3$\sigma$값으로 24.0nm에서 10.7nm 로 개선할 수 있었다.

• 한국농공학회지
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• 제31권2호
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• pp.66-81
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• 1989

The characteristics of resilient modulus(Mr) which dominates the life of pavement and the design of pavement were investigated on the test specimens which were cement treated and non-treated of the three different soil types. The results are summarized as follows : 1. The resilient modulus was decreased by increasing the cyclic deviator stress ($\sigma$d) , especially the resilient modulus was gradually decreased or sometimes increased when the value of ad was greater than 0.75- 1. 0kg/cm$^2$. 2. The resilient modulus was increased by increasing the homogeneous confined stress ($\sigma$do) and such phenomena were distinct on the coarse soils. 3. The resilient modulus was increased by increasing the ratio of confined stress(Kc), and this phenomena were eminent on the coarse soils too, and the higher permanent strain was showed by increasing the value of Kc. 4. In the drained cyclic triaxial compression test, the value of ad, Kc, and (Oho) was introduced by the following interrelated equations which were similar to the Mr model of Cole. Kcn/Mr=K1(J$_2$/ $\tau$oct)K2 ............. (coarse soli) Mcn/Mr=K3($\sigma$dp/ $\tau$f)k4 ...............(fine soils) 5. The stress path was not much affected by the value of Mr, however, moisture content, dry desity, and contant of fines affected the value of Mr. 6. In the soil-cement specimens, the resilient compression strain($\varepsilon$d) was decreased by the increment of the $\sigma$ho, and Mr was decreased by increasing the $\sigma$d 7. In the flexible pavement. the cement treated layer should be designed not to fail by the fatigue before the designed traffic load, and actually the pavement could cover the traffic load to a certain extent under the post-crack phase, therefore farther studies on this phenomena' are required in the design analysis. 8. The finite element computer program (ANALYS) was used for displacement analysis of pavement containing the cement-treated layer, The result showed that the program used for this analysis was proved to be usable.

• 대한원격탐사학회지
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• 제27권4호
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• pp.457-466
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• 2011

본 연구의 목적은 Level 3 type 북한 토지피복도를 작성하고 생물계절 특성을 파악 하는 데 있다. 2008년과 2009년에 촬영된 88장과 8장의 MODIS NDVI를 MVC 하여 질이 향상된 영상에 ISODATA 알고리즘을 적용하였다. 생물계절 상 분석을 기반으로 북한의 토지피복도를 구축하고 중분류에 대해서는 정확도 검정을 하였다. 결과, 총 27개 클래스의 북한 토지피복도가 생산되었다. 토지피복은 17개의 산림 서식지, 토지이용은 7개의 농경지와 2개의 시가지, 그리고 한 개의 수역을 포함한다. Level 3 type 생물계절 특성은 휴지기(${\sigma}^2$ = 0.348)와 식생이 급격히 생장하는 봄철(${\sigma}^2$ = 0.347)의 역동성이 가장 컸다. Level 2 type에 대한 정확도 검정에서, 전체 정확도는 85.85%(851/955), Kappa 계수는 0.84 였다. 현장 접근이 불가능한 북한의 토지피복도 구축에 생물계절 상 분석기법 적용은 오분류를 최소화하고 분류정확도를 향상시키는데 기여하였다.

• 분석과학
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• 제12권3호
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• pp.235-242
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• 1999

점계수법이나 영상분석법으로는 미세조직상 구분이 어렵고 측정이 곤란할 정도로 미량인 석출물들의 분율을 구하는 것이 불가능하다. 본 연구에서는 미량석출물을 전기화학적으로 모재에서 추출한 후, 추출물에 대한 정량 X-선 회절분석법을 이용하여 니켈기 초내열합금 Udimet 720의 기계적성질에 중요한 영향을 미치는 미량석출물인 시그마, 탄소화물, 붕소화물 등의 상분율을 측정하였다. 미량석출물들의 양적 변화를 유도하기 위해 합금을 $800^{\circ}C$에서 3000시간까지 노출시켰을 때, 유지시간이 증가할수록 시그마상의 석출양이 지수함수적으로 증가하였으며 3000시간 정도 유지되면 시그마상 석출이 둔화되어 포화상태에 가깝게 되는 것을 확인하였다. 석출이 완료되는 시점은 약 5000시간 부근으로 예측되며, 최대로 석출할 수 있는 시그마상의 양은 무게비로 5% 정도였다. 한편, $M_{23}C_6$와 $M_3B_2$의 양은 유지시간에 무관하게 무게분율로 0.1~0.5% 범위의 일정한 값을 보였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.589-591
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• 2004

In this paper, we developed a laser distance measurement(LDM) system based on DSP. We applied PPD(Pulsed Phase Detection) algorithm to the LDM system. The PPD algorithm calculate the distance from the LDM system to the object by using phase detection. Reference waveform at a fixed frequency is sampled by both the inner-loop and outer-loop pulse signal. The LDM system detects the difference of phase between the sampled signals. We obtained an accuracy of ${\sigma}=25.5mm$ from the LDM system.

• 한국통신학회논문지
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• 제28권1C호
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• pp.9-13
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• 2003

We consider a two-phase queueing system with Bernoulli feedback. Customers arrive at the system according to a Poison process and receive batch service in the first phase followed by individual services in the second phase. Each customer who completes the individual service returns to the tail of the second phase service queue with probability 1 -$\sigma$. This type of queueing problem cad be easily found in computer and telecommunication systems. By deriving a relationship between the generating functions for system size at various embedded epochs, we obtain the system size distribution. The exhaustive and gated cases for the batch service are considered.

• Journal of Welding and Joining
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• 제8권4호
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• pp.27-34
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• 1990

Integranular corrosion behaviors of KAL (Knife Line Attack) and mechanical properties such as tensile and creep rupture were investigated for the tube material used for nearly 20 years under the condition of 463.deg. C and 28 $kg/cm^2$. Based and weld metal were austenitic stainless steel AISI 321 containing Ti, AISI 347 containing Nb, respectively. KLA is a kind of the intergranular corrosion which often occurs just near the HAZ (heat affected zone) of AISI 321 and AISI 347 stainless steel due to the grain boundary sensitization. In KLA zone, intergranular corrosion crack has propagated outwards from the inner surface and carbides of white and narrow band type assuming as (Cr, Fe) carbide were confirmed. All the delta-ferrite formed in the weld metal during weld solidification has been transformed into sigma-phase since delta-ferrte was exposed for 20 years at 463.deg. C. Elongation was very low at the range from room temperature to 600.deg. C and it was confirmed that creep-rupture properties were not consideralbly affected.

• Corrosion Science and Technology
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• 제2권1호
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• pp.36-40
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• 2003

An attractive combination of corrosion resistance and mechanical properties in the temperature range -50 to $250^{\circ}C$ is offered by duplex stainless steel. However, undesirable secondary precipitation phase such as $\sigma$, $\gamma_2$ and $Cr_2N$ may taken place at the cooling stage from the welding processes. Therefore, this paper describes the influence of different welding procedures such as manual metal arc welding (MMA), tungsten inert gas welding (TIG) and vacuum brazing on corrosion resistance of the welded joint for UNS S31803 duplex stainless steel. Microstructure and chemical compositions of the welded joint were examined. The weight loss of specimens immersed in 6% $FeCl_3$ solution at $47.5^{\circ}C$ for 24-hours was determined and used to evaluate the pitting resistance of duplex stainless steel and their welds. The region of heat-affected zone of specimen obtained by the MMA is much wider than that resulted from TIG, therefore, the weight loss of welds by MMA was larger than that of weld by TIG. The weight loss of brazed specimens cooled from slow cooling rate was larger than those of specimens cooled from high cooling rate, because the precipitation of $\sigma$ phase. Beside that, the weight loss of brazed specimen is greater than those of the welded specimens. The galvanic corrosion was observed in brazed duplex stainless steel joints in the chloride solution.

• JSTS:Journal of Semiconductor Technology and Science
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• 제7권4호
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• pp.267-273
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• 2007

A fractional-N frequency synthesizer supports quadruple bands and multiple standards for mobile broadcasting systems. A novel linearized coarse tuned VCO adopting a pseudo-exponential capacitor bank structure is proposed to cover the wide bandwidth of 65%. The proposed technique successfully reduces the variations of KVCO and per-code frequency step by 3.2 and 2.7 times, respectively. For the divider and prescaler circuits, TSPC (true single-phase clock) logic is extensively utilized for high speed operation, low power consumption, and small silicon area. Implemented in $0.18-{\mu}m$ CMOS, the PLL covers $154{\sim}303$ MHz (VHF-III), $462{\sim}911$ MHz (UHF), and $1441{\sim}1887$ MHz (L1, L2) with two VCO's while dissipating 23 mA from 1.8 V supply. The integrated phase noise is 0.598 and 0.812 degree for the integer-N and fractional-N modes, respectively, at 750 MHz output frequency. The in-band noise at 10 kHz offset is -96 dBc/Hz for the integer-N mode and degraded only by 3 dB for the fractional-N mode.