As unit 1 of Kori was permanently shut down in June 2017, domestic nuclear industry has entered the path of decommissioning. The most important thing in decommissioning is cost reduction. And volume reduction of radioactive waste is especially important. According to the IAEA report, more than 4,000 tons of metallic waste is generated during the decommissioning of a 1,000 MWe reactor and most of these wastes are LLW or VLLW. To reduce amount of metallic waste dramatically, we should choose efficient decontamination method. In this study, we conducted dry ice and bead blasting decontamination. We prepared Inconel-600 and STS-304 specimen with dimensions of 30 mm × 30 mm × 5 mm. Loose and fixed contamination was applied on the surface of specimen using SIMCON method. Bead and dry-ice blasting was conducted by spraying alumina and dry ice pellet at the same pressure and distance for the same time. The removal of loose contamination was observed using microscope. It was found that contaminants are significantly removed using both dry ice blasting and bead blasting. However, some abrasive material remained on the surface of specimen. The removal of fixed contamination was verified by weight comparison before and after experiment and cobalt concentration comparison before and after experiment using X-ray Fluorescence Spectroscope (XRF). At least 90% of the cobalt was removed, but some abrasive particle was also remained on the surface of specimen. In this study, it is confirmed that the effectiveness of manufacturing a large-scale abrasive decontamination facility, and it is expected that this technology can be used to effectively reduce the amount of metallic waste generated during decommissioning.

For the sake of future generations, the management of radioactive waste is essential. The disposal of spent nuclear fuel (SNF) is considered an urgent challenge to ensure human safety by storing it until its radioactivity drops to a negligible level. Evaluating the safety of disposal facilities is crucial to guarantee their durability for more than 100,000 years, a period sufficient for SNF radioactivity to become ignored. Past studies have proposed various parameters for forecasting the safety of SNF disposal. Among these, radiochemistry and electrochemistry play pivotal roles in predicting the corrosion-related chemical reactions occurring within the SNF and the structural materials of disposal facilities. Our study considers an extreme scenario where the SNF canister becomes compromised, allowing underground water to infiltrate and contact the SNF. We aim to improve the corrosion mechanism and mass-balance equation compared with what Shoesmith et al. proved under the same circumstances. To enhance the comprehensibility of the chemical reactions occurring within the breached SNF canister, we have organized these reactions into eight categories: mass diffusion, alpha radiolysis, adsorption, hydrate formation, solidification, decomposition, ionization, and oxidation. After categorization, we define how each species interacts with others and calculate the rate of change in species’ concentrations resulting from these reactions. By summing up the concentration change rates of each species due to these reactions, we redefine the mass-balance equations for each species. These newly categorized equations, which have not been explained in detail previously, offer a detailed description of corrosion reactions. This comprehensive understanding allows us to evaluate the safety implications of a compromised SNF canister and the associated disposal facilities by numerically solving the mass-balance equations.

Zircaloy-4 is utillzed in nuclear fuel rod cladding due to its strength and corrosion resistance. However, it can undergo deformation over time, known as creep, which poses a safety risk in reactors. Furthermore, hydrogen absorption during reactor operation can alter its properties and affect creep rates. Previous research suggests a trend in which hydrogen concentration corelates unidirectionally with creep rates, either increasing or decreasing as the concentration rises. This trend can also be observed in EPRI’s creep model, EDF-CEA Model-3. However, recent literature has suggested that creep behavior may vary depending on the state of hydrogen presence. Therefore, it has become evident that creep behavior can be influenced not only by hydrogen concentration but also by the state of hydrogen presence, whether it is in a solid solution state or precipitated as hydrides. Our study aimed to compare creep behavior in specimens with hydrogen concentrations below and above solubility limits. We fabricated Zircaloy-4 plate specimens with varying hydrogen concentrations and conducted creep tests. The results revealed that specimens below the solubility limit exhibited decreasing creep rates as hydrogen concentration increased, while those above the limit displayed increasing creep rates. This investigation confirms that the state of hydrogen presence significantly impacts creep behavior within Zircaloy-4 cladding. As part of our additional research plans, we intend to conduct creep tests on the material based on its orientation, whether it is in the rolling direction (RD) or the transverse direction (TD). We also plan to perform creep tests on ring specimens. Additionally, for the ring specimens, we aim to evaluate how creep behavior differs between the cold-worked stress-relieved (CWSR) condition and the recrystallized annealed (RXA) condition achieved through high-temperature heat treatment.

As an endemic species in Korea Adenophora erecta S. Lee, Joongku Lee et S. Kim is distributed in a restricted area of Ulleung island. In this study, we confirmed finding only about 60 individuals in Taeha-ryeung in an area measuring 900 m² in size. These data together with previously collected data indicate that this species is in the “Critically Endangered (CR)” category based on taxon evaluation criteria of the IUCN. We propagated this species using seeds of transplanted plant from a site where this plant was first found. The best seed germination was observed in a batch treated with GA3 (500 mg/L) under the sun light and the best plant growth was observed in a bed of nursery soil and rough-sand soil (1:1). The original habitat of A. erecta in Sukpo-dong was successfully restored by transplantation of the propagated young plants.

The FTA card is a quick and easy method to preserve DNA from plant tissues. Its applicability has only been tested in some economically important plants and in research model plants such as rice, potato, tomato, and Arabidopsis. Therefore, DNA preservation with FTA cards in various tracheophytes (196 taxa) was tested in this study based on PCR using DNA barcoding primers. The results indicated that DNAs were successfully preserved with FTA cards in 76.74% of the tested samples and each taxon showed a different preservation rate. Especially, most families in monocots showed high preservation rates (100%) while Asteraceae showed low preservation rate (28.57%) compared to other families. Stored FTA cards were tested again after five years under the same experimental conditions as the previous test. The results showed that DNA was preserved in 54.26% of the samples, indicating that 29.9% of DNA-preserved samples are degraded after five years. However, Araceae, Amaryllidaceae, Asparagaceae, Liliaceae, Melanthiaceae, Brassicaceae, Araliaceae, and Asteraceae samples, of which DNA preservation was confirmed five years earlier showed a 100% preservation rate. This study suggests that the FTA card is a useful tool for DNA preservation in various plant taxa, of which preservation is confirmed in this study (or closely related taxa) and is applicable in the field of population genetics, phylogeny, identifications, inspections, etc.

Cost for plant survey has been dramatically reduced due to the development of mobile technology to obtain pictures with their GPS coordination. We developed a PlantGPS system consisting of an Android application specialized for collecting plant pictures and their locations using mobile devices, a server-side component for uploading data, and a web-based interface for managing and analyzing data. As examples of application of our PlantGPS system, surveys of “plants in Nangsae (Daksum) Island” and “ferns in Chollipo arboretum” were conducted. Results showed that our PlantGPS system could be used to quickly survey plant distribution in restricted area with reasonable time and effort.

Up-to-date manufacturing companies have faced a market-driven environment of pull production order. There should be a difference in operating manufacturing resources according to the type, quantity, and delivery time of manufactured products, because the process situation in pull production is changed by customer orders. And it should be taken into account from the stage of preparing for production such as process design and the placement and utilization of manufacturing resources. However, the feasibility of production plans is limited because most of small manufacturing businesses make production/supply plan of the parts and products assuming that equipment abilities in scheduling is sufficient without managing process standard information systemically. In this study, a discrete event simulation system based on BOM (bill of material), that is F-OPIS (online productivity innovation system), is introduced and a case study on application of the system leading to improving productivities is presented. F-OPIS deals with a decision-problem on production management and it is specialized for small-and- medium sized manufacturing companies. The target company of this case study is a typical small-and-medium sized manufacturing company in Korea, that produces various machined parts. The target company adopts make-to-stock production management to prevent tardy delivery because of fluctuations in demand. Therefore, it is required to apply an efficient inventory control solution for improving productivities. In this paper, based on the constraints of working capacity of manufacturing resources, the bottleneck process is analyzed as production conditions are changed. Consequently, an improvement plan is proposed, that eventually enhances overall utilization rates of resources in the bottleneck process and reduces overall production lead-time and inventory level.

We observed the pollen grains and fruits of six Isodon taxa distributed in Korea using a light microscope and a scanning electron microscope. The muri thickness on the surface of the pollen grains distinguishes Isodon serra from other taxa: the thickness of I. serra is ca. 0.6 μm, while the thicknesses of other taxa are 0.37~0.49 μm. I. inflexus var. canescens has a relatively nutlet small (about 0.93×0.83 mm) compared to other Korean Isodon taxa (about 1.15~1.37×1.02~1.17 mm). Characteristically, a nutlet of I. inflexus var. microphyllus has non-glandular hairs distributed all over its surface. However, I. serra has non-glandular hairs distributed only on the top of the nutlet while it has glandular hairs broadly distributed over the entire nutlet. We suggested that these characters of the pollen and fruit surfaces can be included in the key to Korean Isodon as diagnostic characters to distinguish the above taxa from other Korean taxa.

The taxonomy of the Isodon excisus complex, which comprises I. inflexus var. inflexus, var. transiticus, var. macrophyllus, var. microphyllus, and var. canescens, has been ambiguous and problematic because their morphological characters are variable. To elucidate the taxonomic structure of the I. inflexus complex in Korea, 42 characters were measured from 70 OTUs representing the I. inflexus complex and were analyzed by a principle component analysis (PCA). The principle component axes 1, 2, and 3 (PC1, PC2, and PC3) represents 55.7% of the total variance. The characters showing high loading values for PC1, which have of absolute loading values higher than 0.7, were characters related to the leaf base and leaf teeth and the length of corolla tube. The length of the broadest part to the apex in the leaf, the density of non-glandular hairs on the lower surface of the leaf, and the length and width of the calyx were highly related to PC2 with the absolute loading values higher than 0.7. PC3 does not have any characters which have absolute loading values higher than 0.5. Three-dimensional scatter plots of the OTUs for the PC1, PC2, and PC3 axes showed that there are three taxa in the complex. Each area of I. inflexus var. inflexus, var. transiticus, and var. macrophyllus was completely overlapped, demonstrating that this taxon is I. inflexus var. inflexus. Areas for var. microphyllus and var. canescens were separated from that of var. inflexus in both cases. Therefore, we recognized three varieties, which are I. inflexus var. inflexus, var. microphyllus and var. canescens in the I. inflexus complex in Korea. This result also indicates that I. inflexus var. inflexus has a wide range of morphological variation. The recognition of var. microphyllus and var. canescens is also supported by the result of recent SEM studies of the fruit surfaces of Korean Isodon.

This study aimed at examining the changes of time series and spatial pattern s of tourism climatic conditions using Korea Tourism Climate Index (KTCI) of South Korea. Spatial patterns of KTCI represent climate characteristics in all seasons of South Korea,. KTCI also shows which tourism climate condition inappropriately (appropriately) shows the changes of tourism activity in the summer (winter) season in response to the global warming. KTCI is therefore expected to be a more suitable index than TCI (Tourism Climate Index) when it comes to the incorporation of the global warming into the index. KTCI can also be used for improving the future prediction about tourism climate conditions and provide useful information for the establishment of countermeasure strategies for climate change.

In this paper, we report a self-balancing robot wheelchair which has the capability of keeping upright posture regardless of the terrain inclination in terms of the three dimensional balancing motion. It has the mobility of five degrees of freedom, where pitching, yawing, and forward motions are generated by the two-wheeled inverted pendulum mechanism and the rolling and vertical motions are implemented by the movement of the tilting mechanism. Several design considerations are suggested for the sliding type vehicle body, wheel actuator module, tilting actuator module, power and control system, and the riding module.

성인에 비해 방사선에 민감하고 검사건수가 증가하고 있는 영·유아의 CT 스캔 시의 장기흡수선량을 평가하기 위해 스캔부위를 머리부위와 가슴부위로 구분하고 64 MDCT를 이용하여 축방향 스캔과 나선형 스캔으로 비교했다. 스캔부위에 상관없이 나선형 스캔 시의 선량이 축방향 스캔 시 보다 유의하게 낮은 것으로 나타났다. 축방향 스캔과 비교해서 나선형 스캔 중 피치 1.355를 사용했을 때가 나머지 두 피치(0.525, 0.988)를 사용했을 때보다 가슴부위 스캔의평균 장기흡수선량이 유의하게 높게(평균 -12.03%) 나왔다. 나선형 스캔 시 장기흡수선량이 축방향 스캔보다 평균 20.54% 낮게 나왔다. 결과적으로 인체모형을 통한 장기흡수선량을 평가한 본 연구는 몬테카를로 시뮬레이션 결과값을실증하고, CT 검사를 받는 영·유아의 장기흡수선량의 보다 정확한 평가에 기여할 것이다.

Geant4와 DICOM 파일의 연동을 이용한 몬테카를로 시뮬레이션을 통해 실제 환자의 흡수선량을 산출하는 새로운 방법을 제시하고, Geant4 계산코드의 검증을 위해 MOSFET 선량계를 이용하여 PMMA 모의 팬텀 깊이에 따른 중심에 서의 흡수선량 실측값과 Geant4 시뮬레이션 결과값을 비교하였다. PMMA slab의 불완전한 압착으로 인해 발생한 불 균등한 간격의 공기층이 존재하지 않은 부분에서는 X선 조사야 15 × 15 cm2 와 20 × 20 cm2 에서 각각 0.46 ± 4.69% 와 -0.75 ± 5.19%로 나타났다. PMMA 모의 팬텀의 불완전한 압착에 의해 나타난 오차를 제외하면 Geant4와 DICOM 파일의 연동을 통한 몬테카를로 시뮬레이션에 의한 계산값이 잘 일치함을 알 수 있다.