Korea's Corona 19(COVID-19) quarantine, referred to as 'K-Quarantine', is a globally recognized quarantine system that has achieved both conflicting goals: health and economy. The quarantine system represented by 3T(Test-Trace-Treat) is not a method of blocking an area, but a method of screening and treating infected and non-infected persons. The screening center, one of the key elements of this screening treatment system, has evolved to suit the timing and situation of COVID-19, and has succeeded in initial response by conducting large-scale tests quickly and safely. By analyzing the evolution of screening centers that produced such significant results from a problem-solving point of view, it proved its meaning as a practical success case of creative problem- solving. In addition, the usefulness of TRIZ (Russian abbreviation of Theory of Solving Inventive Problem), a creative problem- solving theory, was confirmed through an analysis of actual verified cases of COVID-19 response. TRIZ is a problem-solving theory created by analyzing the regularity of invention patents, and is widely used not only in the technical field but also in the non-technical fields such as design, management, and education. The results of this study are expected to provide useful meaning and practical examples to researchers interested in system analysis and TRIZ application from a problem-solving perspective.

팀 상황에서 신뢰의 축적과 그 효과성 간의 역동성을 이해하는데 목적을 두고 자율적 프로젝트팀을 대상으로 종단연구를 실행하였다. 신뢰의 진화 개념이 제시된지 25여 년이 되어가지만 이를 실증분석한 연구는 희소하다. 이에 본 연구는 프로젝트팀에서 계산적 신뢰와 지식기반 신뢰가 시간의 흐름에 따라 변화하는지를 살펴보고 초기신뢰와 변화된 신뢰가 팀활성화에 어떻게 영향을 미치는지를 검증하였다. 팀 활성화 변수로는 팀만족, 대인시민행동 및 학습을 채택하였다. 신뢰의 진화를 검증하기 위해서는 신설된 팀을 필요로 하므로 국내 대학생을 대상으로 한학기동안 진 행된 프로젝트팀을 통해서 실험연구를 진행하였다. 연구대상인 팀원들은 한 학기 동안 세 차례의 프로젝 트를 공동작업으로 진행하였고 각 프로젝트가 종료되는 시점에서 신뢰의 변화와 팀활성화 변수들을 측정 하였다.분석 결과, 계산적 신뢰와 지식기반 신뢰는 모두 시간의 흐름에 따라 유의하게 변화하여 높아지고 있었 다. 그리고 두 신뢰 모두 처음 형성된 신뢰와 이후의 변화가 팀만족, 대인시민행동, 그리고 학습에 차별적 인 영향을 미치는 것을 확인하였다. 아울러 연구변수들의 인과관계를 구체적으로 살펴보고자 자기회귀 교차지연 검증을 실시하였고 신뢰와 팀활성화 변수 간에 유의한 교차지연효과를 확인하였다.

In this paper, the conceptual spaces of the diachronic semantic evolution of “gen” are constructed through the diachronic literature surveys, then the cross-dialect/language semantic maps are drawn as a tool to examine the rationality of the diachronic evolution. “Gen (跟)” is an action verb with the meaning of “following (跟隨)”, in Chinese history the dominant words with the semantic field of “following” have experienced the diachronic evolution of “cong (從)”, “sui (隨)” and “gen (跟)”. The development of these three words not only follows the law of parallel grammaticalization, but also each has its own feature. From the comparison diachronic and cross-dialect /language semantic map of the “following (跟隨)” meaning, it can be seen that, non-cognate words with family characteristics may also have the same semantic evolution. Some phenomena in the synchronic regional semantic maps that violate the “semantic map connectivity hypothesis”, may not be due to the complete lack of connection between the two nodes, but due to the choice of semantics of a specific symbolic form in the diachronic development.

Electrochemical water splitting is an important process for next generation of eco-friendly energy systems. The oxygen evolution reaction (OER), which occurs at an anode during the process, requires efficient electrocatalysts to reduce activation energies. Although Ru- or Ir-containing materials show excellent electrocatalytic activities, their high cost is a critical drawback. Consequently, the development of efficient electrocatalysts composed of low-cost metal components is a great challenge. In this study, we develop a new route to produce a hybrid material (Fe–NC) containing Fe3C particles dispersed on the surface of N-doped carbon (NC) materials by heat treatment of a mixture of urea and Fe(II)Cl2(H2O)4. Microscopic analyses prove that the Fe3C particles are placed on the surfaces of thin NC materials. Additionally, various characterizations reveal that the particles contain Fe3C structure. Fe–NC shows good electrocatalytic properties with onset and overpotentials of 1.57 V and 545 mV, respectively, for OER in KOH electrolyte. This study suggests the possibility of the use of Fe3C- based composites as OER electrocatalysts.

The safety assessment of a geological disposal system is performed over a period of hundreds of thousands of years, during which the activity of radionuclides in spent nuclear fuel decreases to natural radioactivity levels. During this period, the biosphere also experiences the long-term evolution of the surface environment including climate, terrain, and ecosystem changes. These changes cause changes in the water balance, which in turn change the pathways of radionuclides in the subsurface. Therefore, it is essential to consider these long-term changes in the surface environment for a reasonable biosphere safety assessment. For this purpose, this study developed the biosphere assessment module considering the long-term evolution of the surface environment, as a sub-module of APro (Adaptive process-based total system performance assessment framework). As a preceding study, the biosphere assessment module was previously developed using COMSOL for hydraulic and radionuclide transport processes, to simulate the pathway of radionuclides traveling from the shallow aquifer to the surface water body and soil. To consider the long-term evolution of the surface environment, the previous module needed to be improved to apply different water balances as boundary conditions of the module at each snapshot, which is a sub-time period divided based on the surface evolution data. To this end, this study utilized SWAT (Soil and Water Assessment Tool) which calculates the water balance using the surface environmental data including climate, terrain, land cover, and soil type. Conceptually, SWAT calculated annual water balance considering surface environmental changes, and certain components (i.e., groundwater recharge and hydraulic head of water bodies) of water balance were transferred to COMSOL as external data to simulate the pathway of radionuclide transport and spatio-temporal variability of radionuclides. At the current stage, the biosphere computational module has been developed to correspond to its conceptual model, and we plan to further test the applicability of the module using different surface environmental data.

The geological disposal of spent nuclear fuel is one of the important problems to be solved worldwide. For the safety of the geological disposal, disposal facility is recommended to be constructed in the deep reducing environment of host rocks. As host rocks, rock salt, argillaceous (clay) rock, and crystalline rock have been considered as stable geological formations in various countries. Although various studies have been conducted on crystalline rocks in Korea, there are still few studies on hydrogeochemical evolution in the deep and reducing environment related to the disposal of spent nuclear fuel. Therefore, this study was conducted to identify hydrogeochemical evolution process in granite aquifer which can affect the stability of disposal facility. Groundwater samples for isotope and chemical analysis were collected quarterly adjacent to KURT (KAERI Underground Research Tunnel). As the depth increased, the groundwater changed from Ca-HCO3 type to Na-HCO3 type under the influence of silicate mineral weathering, and the fluorine concentration increased due to the dissolution of fluorine-bearing minerals. However, hydrogeochemical evolution according to the depth was not observed in some wells because of a hydraulic connection through the fracture zone. In addition, the behavior of nitrate and redox-sensitive metals (Fe, Mn, U, Mo) in groundwater was clearly different in the redox condition. Considering these hydrogeochemical processes and hydrogeological factors, a conceptual model of granite aquifers in and around KURT was established. The results of this study will be used as basic data to understand the hydrogeochemical processes and to evaluate and predict the behavior of radionuclides in granite aquifer system.

Since it takes hundreds of thousands of years for the radiotoxicity of spent nuclear fuel to decrease to natural levels, interactions between each repository barrier, climate change, and geological evolutions are inevitable. These processes should be defined as the long-term evolution FEPs and considered in the performance assessment to ensure the long-term safety of the disposal system. The literature survey on geological characteristics and history of the Korean peninsula was conducted, and the list of A-KRS-FEPs which are directly or indirectly related to long-term evolutions was identified in this study. The ice age and geological change are the capital phenomena considered in the exceedingly long-term evolution before/after climate change. The historical data on ice sheets and permafrost were analyzed to investigate the effects of the ice ages on the Korean peninsula. The sealevel changes were investigated based on the research on the coastal terrace to identify the impact on uplift and shoreline change accompanying the ice age. Also, the survey on the geological history data was conducted from the perspective of tectonic activity, metamorphism, igneous activity, and seismic activities to consider the geodynamic evolution of the Korean peninsula. As results, it was suggested that 14 FEPs were directly related to climate change, 18 FEPs were directly related to geological evolution, and 47 FEPs were indirectly relevant to long-term geodynamics. The consent-based FEPs and scenarios for the long-term evolution will be developed shortly, including most of the critical long-term evolution phenomena defined in this study and which are highly probable in domestic disposal conditions. The evaluation and verification of the APro system for long-term safety will accomplish using these FEPs and scenarios.

The timescale for the post-closure safety assessment of a deep geological repository ranges from ten thousand to a million year. In such a long period of time, the biosphere inevitably undergoes changes. Therefore, the long-term evolution of a biosphere is recognized as an important issue in the post-closure safety assessment of a deep geological repository for spent fuels. In this study, we reviewed the approaches to address the long-term evolution of a biosphere. The major drivers of longterm evolution of a biosphere are the climate change and the resulting landscape development. They can affect the hydrogeological and hydrogeochemical characteristics of a biosphere, and then the radionuclide migration through the biosphere followed by the exposure doses for the critical groups. In addition, human activities and the social developments can affect the climate change resulting in the long-term evolution of a biosphere. To make a biosphere assessment, the long-term evolution scenarios for the biosphere should be formulated considering these climate change, landscape development, and human activities. In addition, features, events, and processes (FEPs) that affect the long-term evolution of a biosphere should be used. According to the Safety Case reports of Finland, the major long-term evolution scenario drivers of a biosphere are local sea-level change due to climate change and land use related to crop type, irrigation procedures, livestock, forest management, construction of a well, and demographics. The climate change causing the local sea-level change can be simulated using various earth system models such as CLIMBER-2, MPI/UW, and UVic and an icesheet model such as SICOPOLIS. The review results of this study and FEPs related to the climate change, the landscape development, and human activities will be used to formulate long-term evolution scenarios for the safety assessment of a deep geological repository for spent fuels.

In recent years, the importance of the thermo-hydraulic-mechanical-chemical coupled processes is increasing in the performance assessment (PA) of the high-level radioactive waste repository. In the case of mechanical behavior, it is very important because it can affect fluid flow and radionuclide transport by changing the porosity and permeability of the medium. In particular, Excavation Damaged Zone (EDZ) should be considered essential in PA because the migration of radionuclide is affected by the enhanced hydraulic transmissivity and altered geomechanical behavior of EDZ. Furthermore, due to various thermo-hydraulic behaviors such as decay heat generated from radioactive waste, pore water pressure increase, and swelling pressure of bentonite buffer material, mechanical evolution is occurred which may change the size and physical properties of EDZ. Therefore, to solve this problem, analysis of coupled thermal-hydraulic-mechanical (THM) processes with the effect of long-term evolution of EDZ due to the mechanical behavior should be accompanied. In this study, numerical model for the long-term evolution due to mechanical behavior considering EDZ using the Adaptive Process-based total system performance analysis framework for a geological disposal system (APro) proposed by the Korea Atomic Energy Research Institute (KAERI). In the case of EDZ, the concept of Mazars’ damage evolution model was applied to simulate the behavior using the continuum model, and the change in hydraulic properties according to the degree of damage was considered. To investigate the importance of mechanical behavior in PA, the results were compared by performing numerical analysis according to the presence or absence of mechanical analysis. Finally, numerical analysis considering the mechanical evolution of EDZ was conducted using the model developed in this study to investigate the effect of EDZ.

It can take hundreds of thousands of years for decreasing radiological effects of high-level radioactive wastes to those of natural background radiation. Therefore, long-term time scale should be considered in order to demonstrate performance and safety of deep geological disposal of the radioactive wastes. The changes of surface environment for these long-term time scale can have influence on safety analysis by changing transport path of radionuclides from the radioactive wastes. Changes in climate is considered as one of main factors causing the long-term changes of the surface environment. The own effects and interactions of climate with other components of the geological disposal system are organized in features, events, and processes (FEPs). In this study, some natural processes occurred by changes of climate were suggested and the connectivity between each process is proposed based on the relation of the FEPs concerned with the changes of climate and surface environment. The processes were classified into global and regional/local scales and was analyzed, respectively. Then, the influences of the processes on shallow groundwater and surface water body environment, which might be transport path of radioactive nuclides in local/site scales, were expected. As the proposed connection demonstrate the order or hierarchical relations of the natural processes, it can shows that some output by a certain process may be input of other process connected the former process in numerical simulations for interpreting the processes. If the connection may be considered to be suitable to represent longterm changes of the surface environment, it can be evaluated that the expected scenarios based on the connection is also proper. In addition, it can be helpful in selecting factors to be studied more detailed in terms of climate change for expecting long-term changes in the surface environment by analysis on the input and output data. The results of this study can be used as basic approaches to represent the long-term changes in the surface environment caused by specific natural processes from changes of climate. It will be also helpful for formulating scenarios related to long-term evolution in the surface environment required for performance and safety assessments of the deep geological disposal.

Through constructing statistical fracture network model based on discrete element method, the evolution characteristics of the fracture aperture had been directly simulated and evaluated caused by redistributed stress after the borehole excavation. This study focuses on the size effect of the discrete element method for the analysis of the effective distance of fracture aperture change after the borehole excavation. A two-dimensional trace-type domain with a maximum size of 1.1 m2 was created using a discrete fracture network with stochastic information of KURT. A total of eight domains with different sizes were constructed from the largest domain area to the 0.4 m2 analysis area. The aperture change ratio which can be depending on the domain size was examined. The ratio was investigated by comparing the aperture size before and after the simulation of borehole excavation. In addition, the effective range of aperture changes was analyzed by comparing the re-distribution distance from the center of the borehole. Based on dimensional analysis, input variables (borehole radius, occurrence distance of aperture changes, domain size) were modeled using exponential distribution form. Through the analysis model, two dimensionless variables were derived to investigate the expected distance of the aperture changes and appropriate DFN domain size for simulating bole excavation. As an application example of the 3-inch borehole simulation, the analysis model predicted that the range of aperture changes could occur within a radius of about 0.98 m from the borehole center, and the suitable size of the model had been inferred as about 5 × 5 m for minimizing the domain size effect.

Deep geological disposal with multiple barriers composed of engineered and natural barriers has been considered as the most suitable disposal method for high level nuclear wastes. In terms of the geological evaluation factors, brittle structures such as fractures and faults should be characterized around the repository site, because radionuclides transfer mainly with groundwater in the subsurface and groundwater flows through discontinuous brittle structures. The geological survey for the characterization of deep geological repository sites is widely conducted by narrowing the survey area from regional scale down to local scale, which could be divided into three steps: 1) using remote sense or geophysical survey, 2) trench and drill core logging including field survey based on the first step, 3) detailed geological survey in the tunnel. In this study, we analyzed the distribution of geological structures to derive the history of brittle deformation in and around the KURT (KAERI Underground Research Tunnel) site located in the KAERI (Korea Atomic Energy Research Institute). The bedrock of the KURT site is mainly consist of Jurassic two-mica granite, which is extensively intruded by andesitic dikes of Cretaceous with N-S to NE-SW strikes. The two-mica granite in the study area was deformed in a ductile deformation environment and has been overprinted by major geological structures such as faults, dikes, veins, and joints. From this study, we identified 8 brittle deformation events based on the cross-cutting relationship among the geological structures, which are obtained from the analyses in and around the KURT. In order to evaluate the reactivation and fluid flow potential of brittle structures, it is essential to determine the characteristics and ages of the brittle structures and the composed rocks around the site.

Disposal facilities for radioactive waste shall be sited to provide isolation from the accessible biosphere. The features shall aim to provide this isolation for tens of thousands to a million years after closure. For the safety assessments of repository, the long-term natural evolution and possible events of the site, that can cause disturbances to the facility over the period of interest, should be considered. Geological development processes that the site have been experienced can contribute to understanding and descripting the present-day conditions. Moreover, knowledge of the past is necessary to predict the future evolution of the site. With regard to disposal site, understanding past geological evolution history allows to access the possibility of hazardous events of the site that can cause disturbances to the facility over the period of interest, and to verify the change in the geological environment is within the safe performance range even after the period of interest. In addition, certain parameters that change with the geological evolution can affect the hydrological and geochemical characteristics which are essential to disposal performance. There are various factors in the evolution of the geological environment, but not all are related to disposal safety. The objective of this research is to develop a geological reconstruction method considering factors that should be derived preferentially for the geological characteristics of the disposal site and the evaluation of the long-term safety. As a preliminary study on this, we investigated case studies related to geological reconstruction of overseas disposal research institutes, and reviewed which factors are suitable for the domestic granitoid distribution environment. It is expected that systematic and consistent results will be possible in the future through this methodology.