• 한국정보처리학회논문지
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• 제3권1호
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• pp.107-117
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• 1996

본 논문에서는 가상 공유 기억장치(VSM)를 기반으로 에이전트들간의 통신 및 협조 가 이루어지는 분산 문제 해결(DPS)을 위한 개념적 모델을 제안하였다. 이 모델에서 DPS 시스템을 구성하는 모든 에이전트는 분산된 환경에 있는 모든 기억장치를 단일의 공유 기억장치로서 취급하며, 따라서 그 곳에 있는 모든 데이터와 작업, 실행 결과 등을 엑세스할 수 있다. 에이전트들이 데이타와 실행의 중간 결과 및 다른 에이전트에게 요 청할 작업등을 VSM에 출력하고, 또한 VSM의 내용을 읽거나 실행함 으로써 하나의 복잡한 문제를 협조적으로 해결하게 된다. 또한, 본 논문에서는 제안한 모델을 기반으로 DPS 시스템을 구축 할 수 있도록 Network Linda를 이용하여 DPS 시스템 개발 환경(DPS-VSM) 을 설계하였다. 또, VSM을 기반으로 하는 DPS 시스템을 시뮬레이션한 예를 제시함으로써 제안한 모델의 유용성을 보이고, DPS-VSM과 기존의 다른 DAL 프로그래밍 쉘의 특성을 비교함으로써 제안한 모델을 분석하였다.

• 생명과학회지
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• 제23권4호
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• pp.479-486
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• 2013

대장균에서 DNA 결합 단백질로 확인된 DNA-binding Protein from Staved cells (DSP)는 DNA를 보호하는 중요한 기능을 한다는 것을 보여주었다. 이 연구의 목표는 야생형 대장균과 dps 유전자 결손 대장균(${\Delta}dps$ E.coli)의 특성 비교를 통해 여러 종류의 스트레스에 대해 대장균에서 DPS의 기능적 역할을 설명하는 것이다. 다양한 스트레스 상태에서 자외선 흡광도계(UV-spectrophotometer)를 이용하여 야생형 대장균과 dps 유전자 결손 대장균의 세포성장을 측정하였으며, 각각의 대장균 세포 성장 속도를 비교함으로써 우리는 대장균에 존재하는 DPS 단백질의 기능적 역할을 확인하였다. 야생형 대장균에 비해 dps 유전자 결손 대장균은 영양분 결핍, 산성화, 열충격, 다양한 활성산소종 스트레스들에 민감한 현상을 나타내었으며, 이것은 DPS가 다양한 극단적인 스트레스에 중요한 기능을 한다는 것을 제안하였다. 결론적으로 대장균의 DPS는 다양한 환경적인 스트레스로부터 DNA와 강하게 결합하여 유지함으로써 세포를 보호하고 세포성장에 결정적인 기능을 한다는 것을 증명하였다.

• Journal of Microbiology and Biotechnology
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• 제17권9호
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• pp.1452-1459
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• 2007

The Dps protein, which is overexpressed in harsh environments, is known to playa critical role in the protection of DNA against oxidative stresses. In this study, the roles of Fur in the expression of the dps gene in Salmonella and the protection mechanisms against oxidative stress in Salmonella cells preexposed to iron-stress were investigated. Two putative Fur boxes were predicted within the promoter region of the S. typhimurium dps gene. The profile of dps expression performed by the LacZ reporter assay revealed growth-phase dependency regardless of iron-status under the culture conditions. The fur mutant, $_X4659$, evidenced a reduced level of ${\beta}$-galactosidase as compared to the wild-type strain. The results observed after the measurement of the Dps protein in various Salmonella regulatory mutants were consistent with the results acquired in the reporter assay. This evidence suggested that Fur performs a function as a subsidiary regulator in the expression of dps. The survival ability of Salmonella strains after exposure to oxidative stress demonstrated that the Dps protein performs a pivotal function in the survival of stationary-phase S. typhimurium against oxidative stress. Salmonella cells grown in iron-restricted condition required Dps for full protection against oxidative stress. The CK24 (${\Delta}dps$) cells grown in iron-replete condition survived at a rate similar to that observed in the wild-type strain, thereby suggesting the induction of an unknown protection mechanism(s) other than Dps in this condition.

• 한국입자에어로졸학회지
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• 제17권2호
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• pp.37-42
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• 2021

Although the installation of droplet protection screen (DPS) is known to prevent droplet transmission, there is still a lack of knowledge in effectiveness of DPS installation to block the airborne transmission. In this study, the prevention ability of DPS against airborne transmission was evaluated according to the DPS height. When the DPS was not installed, the maximum concentration of PM1.0 at the location opposite to infected person was 35% of that at the infected person location. When the DPS was installed, the DPS effectively prevented the airborne transmission, consequently approximately 7% of generated particles were measured at the opposite location from particle generation position (infected person location). The prevention ability of DPS increased with DPS height, the maximum prevention efficiency of 95.1% was obtained when the DPS height was 900mm. Moreover, the speed of airborne transmission was delayed by installation of DPS, and the delay time increased with DPS height.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권5호
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• pp.511-518
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• 2016

The dynamic positioning system (DPS) maintains an offshore vessel's position and heading under various environmental conditions by using its own thrust. DPS is regarded as one of the most important systems in offshore vessels. So, efficient operation and maintenance of the DPS are important issues. To monitor the DPS, it is necessary to define an appropriate key performance indicator (KPI) that can express the condition of the DPS from the perspective of operational efficiency and maintenance. In this study, a new KPI for the DPS is proposed considering the efficiency of the machinery and controller, the energy efficiency, and the environmental conditions in which the DPS is operated. The KPI is defined as a function of control deviation, energy consumption, and environmental load. A normalization factor is used to normalize the effect of environmental load on the KPI. The KPI value is calculated from DPS simulation and model test data. The possibility of applying the KPI to monitoring of DPS condition is discussed by comparing the values. The result indicates the feasibility of the new KPI.

• 생명과학회지
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• 제17권2호통권82호
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• pp.298-304
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• 2007

Salmoenella는 대표적인 intracellular pathogen으로 숙주의 면역 세포인 macrophage 내에서 살아남아 이들을 매개로 숙주의 몸 전체를 이동해 가면서 전신성 감염을 일으킨다. 살모넬라는 숙주 세포 내부의 이러한 극한 환경을 극복하기 위해서 다양한 방어 기작을 가진다. 본 연구에서는 복합적인 스트레스가 작용하는 정지기 Salmonella에서 특이적으로 발현되는 단백질에 주목하였다. 정지기 상태의 Salmonella에서 약 20 kDa의 단백질이 특이적으로 많이 발현되었으며, 세포질 분획을 통해 이 단백질이 세포질 부분에 존재함을 알 수 있었다. MALDI-TOF 분석을 통해 이 단백질이 $\b{D}NA$ binding $\b{p}rotein$ in $\b{s}tationary$ phase (Dps) 단백질임을 확인하였다. Dps 단백질은 스트레스가 주어진 상황에서 DNA에 비특이적으로 결합하여 DNA가 안정한 형태를 유지하도록 하여 스트레스로부터 염색체를 보호하는 역할을 하는 것으로 알려져 있다. 이후의 연구를 위하여 과발현하여 정제한 Dps 단백질을 토끼에 주사하여 Dps 특이적인 항체를 제조하였다. dps 발현에 영향을 미치는 조절자 단백질을 알기 위하여 다양한 S. typhimrium 돌연변이주들 내에서의 Dps 단백질양을 조사하였다.

• 열처리공학회지
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• 제33권4호
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• pp.173-179
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• 2020

The purpose of this study was to investigate comparatively the microstructural characteristics and hardness of discontinuous precipitates (DPs) in Mg-9%Al alloy, which were formed by continuous cooling (CC) from 678 K to RT and isothermal aging (IA) at 413 K, respectively. In as-cast state, the Mg-9%Al alloy consisted of partially divorced eutectic β(Mg₁₇Al₁₂) particles with a small amount of DPs showing (α+β) lamellar morphology adjacent to the β particles. The DPs formed by CC had interlamellar spacings in a broad range of 0.85~2.12 ㎛ (1.51 ㎛ in average) owing to the various formation temperatures in response to continuous cooling process. Meanwhile, the DPs formed by IA had relatively narrower interlamellar spacings of 0.14~0.29 ㎛ (0.21 ㎛ in average), which is associated with the low and constant formation temperature. Thinner and higher volume fraction of β phase layers were noticeable in the DPs formed by IA. Higher hardness values were obtained in the DPs formed by IA than the DPs formed by CC, which may well be ascribed to the finer lamellar structure and higher β phase content of the DPs formed by IA.

• 열처리공학회지
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• 제33권6호
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• pp.271-276
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• 2020

The relationship between the hardness and interlamellar spacing of discontinuous precipitates (DPs) formed by continuous cooling was studied for Mg-9%Al-1%Zn alloy. After solution treatment at 683 K for 24 h, the specimens were cooled to room temperature with different cooling rates ranging from 0.2 to 2 K·min^-1, in order to obtain DPs with various interlamellar spacings. It was found that cooling rate of 2 K·min^-1 yielded only small amount of nodular DPs at the grain boundaries, while cooling rates below 2 K·min^-1 yielded both DPs and continuous precipitates (CPs). The volume fraction of DPs increased with increasing cooling rate up to 0.5 K·min^-1, over which it abruptly decreased. The hardness of DPs was increased with an increase in the cooling rate, whereas the interlamellar spacing of the DPs was decreased with respect to cooling rate. The hardness of the DPs formed by continuous cooling was correlated with the interlamellar spacing and can follow a Hall-Petch type relation as in the case of pearlite with lamellar morphology.

• 열처리공학회지
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• 제34권6호
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• pp.302-308
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• 2021

The aim of this study was to investigate the dependence of the hardness and thermal conductivity on the volume fraction of discontinuous precipitates (DPs) in the Mg-9.3%Al alloy with (α-(Mg)+DPs) dual phase structure. In order to obtain various DPs volume fractions, the alloy was solution-treated at 688 K for 24 h and then aged at 418 K for up to 144 h. The volume fraction of DPs increased from 0% to 63% with an increase in the aging time up to 72 h, over which, continuous precipitation was observed within the α-(Mg) grains. It is noticeable that the hardness and thermal conductivity of the alloy increased linearly with the volume fraction of DPs. The improved hardness and thermal conductivity with respect to volume fraction of DPs are closely associated with the higher hardness of the DPs with fine (α+β) lamellar structure and the lower Al concentration in the α phase layer of the DPs, respectively.

• 한국위성정보통신학회논문지
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• 제9권2호
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• pp.12-17
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• 2014

본 논문에서는 고전압에서 동작하는 마이크로칩의 안정하고 튼튼한 정전기 보호 성능을 구현하기 위해 이중 극성 소오스를 갖는 DPS_EDNMOS 변형소자가 제안되었다. 제안된 DPS는 N+ 소오스로 부터 전자 풍부 영역이 측면 확산되는 것을 방지하기 위해 N+ 소오스 측에 P+ 확산층을 의도적으로 삽입한 구조이다. 시뮬레이션 결과에 의하면 삽입된 P+ 확산층은 고전자 주입에 의해 발생하는 깊은 전자채널의 형성을 효과적으로 막아주고 있음을 알 수 있었다. 따라서 종래의 EDNMOS 표준소자에서 문제시 되었던 더블 스냅백 현상을 해결할 수 있었다.