• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2650-2659
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• 2022

The dense granular flow spallation target is a new target concept proposed for an Accelerator-Driven Sub-critical (ADS) system. In this paper, the beam-target configurations of a tungsten granular flow target for the ADS with a thermal power of 1 GW is explored. The beam profile options using different scanning methods are discussed. The critical geometry parameters are adjusted to investigate the performance of the granular target from the aspects of neutron efficiency, stability and temperature distribution in target medium. To figure out how the target under accident conditions would behave, different clogging conditions are induced in the simulation. The dynamic processes are analyzed and some important parameters such as abnormal temperature rise and beam cutoff time window are obtained. The response of the sub-critical reactor to a clogging accident is also investigated. It is indicated that the monitoring of the granular flow by the neutron detectors in the sub-critical core will be effective.

• Earthquakes and Structures
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• 제18권1호
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• pp.45-56
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• 2020

The application of critical excitation method with displacement-based objective function for multi degree of freedom (MDOF) systems is investigated. To this end, a new critical excitation method is developed to find the critical input motion of a MDOF system as a synthetic accelerogram. The upper bound of earthquake input energy per unit mass is considered as a new constraint for the problem, and its advantages are discussed. Considering this constraint, the critical excitation method is then used to generate synthetic accelerograms for MDOF models corresponding to three shear buildings of 10, 16, and 22 stories. In order to demonstrate the reliability of generated accelerograms to estimate dynamic response of the structures, three target ground motions with considerable level of energy contents are selected to represent "real critical excitation" of each model, and the method is used to re-generate these ground motions. Afterwards, linear dynamic analyses are conducted using these accelerograms along with the generated critical excitations, to investigate the key parameters of response including maximum displacement, maximum interstory drift, and maximum absolute acceleration of stories. The results show that the generated critical excitations can make an acceptable estimate of the structural behavior compared to the target ground motions. Therefore, the method can be reliably implemented to generate critical excitation of the structure when real one is not available.

• 한국국방경영분석학회지
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• 제17권1호
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• pp.159-176
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• 1991

The probability of target survival is the most important factor in the target assignment, Most of the studies about it have assumed the case of one target and ane weapon type. Therefore, they can not be applied to the real situation. In this paper. the quantity and type of enemy assets of the friendly force are considered simultaneously. Considered defense type is the coordinated defense with no impact point prediction. The objective function is to minimize the expected total survival value of targets which are scattered in the defense area. The rules of aircraft assignment are as follows : first, classify targets into several groups, each of those has the same desired damage level secondly. select the critical group which has the least survival value in accordance with the additional aircraft assignment, and finally. assign the same number of attack assets against each target in the critical group. In this paper, the attack assets, the escort assets, and the defense assets are considered. The model is useful to not only the simple aircraft assignment problem but also the complicated wargame models.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2000년도 춘계 학술대회 논문집 통권 3호 Proceedings of the 2000 KSRS Spring Meeting
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• pp.9-9
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• 2000

For the planning of future land use for economic activities, an essential component is the identification of the vulnerable areas for natural hazard and environmental impacts from the activities. Also, exploration for mineral and energy resources is carried out by a step by step approach. At each step, a selection of the target area for the next exploration strategy is made based on all the data harnessed from the previous steps. The uncertainty of the selected target area containing undiscovered resources is a critical factor for estimating the exploration risk. We have developed not only spatial prediction models based on adapted artificial intelligence techniques to predict target and vulnerable areas but also validation techniques to estimate the uncertainties associated with the predictions. The prediction models will assist the scientists and decision-makers to make two critical decisions: (i) of the selections of the target or vulnerable areas, and (ii) of estimating the risks associated with the selections.

• 영어어문교육
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• 제17권4호
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• pp.313-337
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• 2011

The purpose of the study is to investigate the effectiveness of the cultural instruction based on the critical pedagogy through film. The participants were 21 college students enrolling 'Understanding American/British culture'class and the class was 15 week long. During class, they discussed and selected the cultural topics related to the movies, complete the research papers, and then gave presentations. The students' portfolio, which consists of the goal statements, research papers, and the reflective journals, was analyzed to investigate the effectiveness of the instruction. The results showed that the instruction was effective in five aspects. They are, 1)accumulation of the cultural knowledge, 2)better understanding of the target culture and its people, 3)acquisition of the critical perspectives toward the target and their own cultures, 4)teaching method, and 5)increase of the motivation for studying other cultures. The study suggested that the instruction should be applied to English-medium class with more advanced students.

• 한국건축시공학회지
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• 제18권6호
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• pp.595-602
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• 2018

건설공사의 공정 계획에 많이 사용되는 네트워크 방식의 공정표는 CPM방식과 PERT 방식으로 분류할 수 있다. 네트워크 공정표에서는 주공정선의 산정은 전진 계산과 후진 계산을 통하여 가장 합계기간이 크게 산출되는 경로를 선택하는 방식에 의하는 것이 일반적이다. CPM 기법에서는 각 액티비티의 소요기간이 고정된 값으로 제시되므로 이를 기반으로 하여 주공정선의 산정이 용이하다. 그러나 PERT 네트워크에서는 소요기간이 확률적으로 주어지므로 단순히 특정 경로 상 액티비티 기간의 합계만으로 주공정은 정하는 것은 불합리하며, 확률에 기반하여 산정된 예상기간에 의해 최가능 주공정으로 제시되어야만 PERT의 목적에 부합할 것이다. 이는 목표 기간에 따라 주공정선이 변화할 수 있으며, 경우에 따라서는 예상 기간이 더 작은 경로가 최가능 주공정이 될 수 있음을 의미한다. 이러한 개념에 의거하여 본 연구에서는 PERT 네트워크 공정표에서 경로별로 예상기간의 비교를 통해 확률적 의미를 가진 최가능 주공정을 도출하는 기법을 제안하는 것을 목적으로 진행한다. 체계적인 대안 경로 도출을 위해 작업 구획과 작업 공정이 교차하여 반복적으로 진행하는 방식의 네트워크 반복 작업 공정표를 대상으로 하여 대안 경로 도출 방식을 제시하였으며, 도출된 경로를 대상으로 예상 기간과 표준 편차를 산출하여 예상기간이 목표 기간을 초과할 확률을 기반으로 하여 최가능 주공정을 산출하는 기법을 제안하였다. 사례 연구를 통해 최가능 주공정은 고정된 경로가 아니며 목표 기간과 표준편차에 따라 변화할 수 있음을 예시한다. 본 연구에서 제시된 기법은 건설 공사와 같이 목표 공사기간이 변화하는 상황에서 유용하게 활용될 수 있을 것이며 기간 예측의 리스크를 명확화하는데 도움을 줄 수 있을 것으로 기대된다.

• 대한인간공학회지
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• 제28권4호
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• pp.71-76
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• 2009

Effects of dark adaptation have large safety implications. This study was aimed to investigate the effects of varying illuminance and the size of critical detail on visual performance (i.e., time-to-detect) in a dark room environment. While adapting to the dark environment, ten subjects were asked to detect and answer simple numerical expressions under 9 experimental conditions (3 illuminance level $\times$ 3 target size). The ANOVA results revealed that the time-to-detect was significantly affected by both of the illumination level and the size of critical detail. As illumination increased from 10 lux to 20 lux, the time-to-detect was significantly declined. For the size of critical detail, 0.5/min size (i.e., equal to 2 minutes of visual angle) resulted in a shorter time-to-detect, as compared to 0.7/min size (i.e., equal to 1.6 minutes of visual angle). Potential applications of this research include the development of design guidelines for illumination and warning signs in poorly illuminated viewing environments.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2004년도 춘계공동학술대회 논문집
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• pp.343-346
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• 2004

The purpose of our research is to identify the critical variables and to develop a new methodology for market segmentation of online game market. Our research tested the model with Korean online game users because Korean online game industry is the frontier of global online game industries. Conclusively, the critical variables are the suitability of feedback, the reality of design, the precision of information and the involvement of virtual community. The analysis of segmentation shows that the primary target audiences are positively influenced by the reality of design and the involvement of virtual community. To attract the primary target audiences, online game companies should develop strategies depending on the effectiveness of the variables and the demographic and behavioral characteristics of target audiences.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 춘계학술발표회논문집(1)
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• pp.660-665
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• 1998

The feasibility study on conceptual design methodology for accelerator-driven sodium-cooled sub-critical transmutation reactors has been conducted to optimize the design parameters from the scale laws and validates reactor performance with the integrated code system. A 1000 MWth sodium-cooled sub-critical transmutation reactor has been scale and verified through the methodology in this paper, which is referred to advanced Liquid Metal Reactor (ALMR). a Pb-Bi target material and a partitioned fuel are the liquid phases, and they are cooled by the circulation of secondary Pb-Bi coolant and by primary sodium coolant, respectively. Overall key design parameters are generated from the scale laws and they are improved and validated by the intergrated code system. Intergrated Code System (ICS) consist of LAHET, HMCNP, ORIGEN2, and COMMIX codes and some files. Through ICS the target region, the core region, and thermal-hydraulic related are analyzed once-through. Results of conceptual design are attached in this paper.

• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.965-970
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• 2005

In our previous study [14], we found that heat-shock exposure did not stimulate the neutral trehalase activity in Sacchromyces cerevisiae KNU5377, but did in ATCC24858. Consequently, the trehalose content in KNU5377 became 2.6 times higher than that in ATCC24858. Because trehalose has been shown to stabilize the structure and function of some macromolecules, the present work was focused to elucidate the relationship between trehalose content of these strains and thermal stabilities of whole cells, through differential scanning calorimetry (DSC), and to predict critical targets calculated from the hyperthermic cell killing rates. These analyses showed that the prominent DSC transition of both strains gave identical $T_m$ (transition temperature) values in exponentially growing cells, and that the $T_m$ values of critical targets was about $3^{\circ}C$ higher in KNU5377 than in ATCC24858. Both heat-shocked KNU5377 and ATCC24858 cells displayed similar shifts in their DSC transition profiles. On the other hand, the $T_m$ value of the critical target of KNU5377 was decreased by $2.1^{\circ}C$, which was still higher than ATCC24858 showing no changes. In view of these results, the intrinsic thermotolerance of KNU5377 did not appear to result from the stability of entire cellular components, but rather possibly from that of particular macromolecules, including critical targets, even though it should be investigated in more details. Although the trehalose levels in heat-shocked cells are significantly different, as described in our previous study [14], the overall pattern of thermal stabilities and their predicted critical targets in two heat-shocked strains seemed to be identical. These data suggest that the trehalose levels examined before and after heat shock of exponentially growing cells are not closely correlated with the stabilities of whole cells and/or critical targets in both yeast strains.