소형 선박(<499 GT)이 전체 선박의 46%를 지배하고 있어 상대적으로 많은 CO2 배출가스를 가지고 있다고 결론지을 수 있다. 최 적의 Trim 조건에서 운전하면 선박의 저항을 감소시킬 수 있어 온실가스가 적게 발생할 수 있다. Trim을 최적화하는 가장 저렴한 방법 중 하 나는 최적의 Longitudal Center of Gravity(LCG)를 얻기 위해 무게 분포를 조정하는 것이다. 따라서 본 연구에서는 소형 선박의 저항에 대한 LCG 변화의 영향을 경험적 및 수치적 해석을 통해 연구하고자 한다. 선체를 설계하는 Savitsky 경험식은 Maxsurf Resistance의 방법으로 사용 된다. 수치해석에는 STAR-CCM+ 상용 CFD(Computational Fluid Dynamics) 소프트웨어가 사용되지만 최종적으로 선박 설계 과정 이후 최적의 LCG를 얻기 위해 전체 저항을 비교한다. 결론적으로 Froude Number 0.56에서는 수치해석에 의해 전체 길이(LoA) 46.2%에서 최적의 LCG를 달성하고 Froude Number 0.63에서는 43.4% LoA를 달성하여 29.2% LoA에서 기준점에 비해 최대 41.12% - 45.16%의 상당한 저항 감소를 얻을 수 있다.

The objectives of this paper are: (1) to conduct the thermal analyses of the disposal cell using COMSOL Multiphysics; (2) to determine whether the design of the disposal cell satisfies the thermal design requirement; and (3) to evaluate the effect of design modifications on the temperature of the disposal cell. Specifically, the analysis incorporated a heterogeneous model of 236 fuel rod heat sources of spent nuclear fuel (SNF) to improve the reality of the modeling. In the reference case, the design, featuring 8 m between deposition holes and 30 m between deposition tunnels for 40 years of the SNF cooling time, did not meet the design requirement. For the first modified case, the designs with 9 m and 10 m between the deposition holes for the cooling time of 40 years and five spacings for 50 and 60 years were found to meet the requirement. For the second modified case, the designs with 35 m and 40 m between the deposition tunnels for 40 years, 25 m to 40 m for 50 years and five spacings for 60 years also met the requirement. This study contributes to the advancement of the thermal analysis technique of a disposal cell.

The high-level radioactive waste repository must ensure its performance for a long period of time enough to sufficiently reduce the potential risk of the waste, and for this purpose, multibarrier systems consisting of engineered and natural barrier systems are applied. If waste nuclides leak, the dominating mechanisms facilitating their movement toward human habitats include advection, dispersion and diffusion along groundwater flows. Therefore, it is of great importance to accurately assess the hydrogeological and geochemical characteristics of the host rock because it acts as a flow medium. Normally, borehole investigations were used to evaluate the characteristics and the use of multi-packer system is more efficient and economical compared to standpipes, as it divides a single borehole into multiple sections by installing multiple packers. For effective analyses and groundwater sampling, the entire system is designed by preselecting sections where groundwater flow is clearly remarkable. The selection is based on the analyses of various borehole and rock core logging data. Generally, sections with a high frequency of joints and evident water flow are chosen. Analyzing the logging data, which can be considered continuous, gives several local points where the results exhibit significant local changes. These clear deviations can be considered outliers within the data set, and machine learning algorithms have been frequently applied to classify them. The algorithms applied in this study include DBSCAN (density based spatial clustering of application with noise), OCSVM (one class support vector method), KNN (K nearest neighbor), and isolation forest, of which are widely used in many applications. This paper aims to evaluate the applicability of the aforementioned four algorithms to the design of multi-packer system. The data used for this evaluation were obtained from DB-2 borehole logging data, which is a deep borehole locates near KURT.

Bombyx mandarina (Lepidoptera: Bombycidae), the presumed ancestor of B. mori, has long been a subject of study to illustrate the geographic relationships in connection with origin of B. mori. We report 97 mitochondrial genome (mitogenome) sequences of B. mandarina collected from Korea and Japan. Phylogenetic and population genetic analyses showed that all individuals of B. mandarina collected in Korean localities formed a strong group together with all individuals originated from northern China (mainly north of the Qinling-Huaihe line) and some of southern China. This group was placed as the sister group to B. mori strians suggesting that this group had been served as an immediate progenitor for B. mori.

본 연구는 소셜미디어 이미지를 이용하여 대구광역시 내 반려견 산책 선호장소와 특징을 분석하 였다. 2020년부터 2022년까지 약 2년간의 시간적 범위를 기반으로 ‘#반려견산책’ ‘#강아지산책’, ‘#개산책’ 세 가지의 인스타그램 해시태그를 활용해 분석을 시행하였다. 그 결과 첫째, 추출된 622 건의 위치 데이터를 바탕으로 대구광역시 내 반려견 인기 산책 장소는 총 13개인 것으로 나타났으 며, 상위 세 개 장소의 경우 국채보상공원, 두류공원, 수성못인 것으로 나타났다. 둘째, 반려견 동반 산책 선호장소의 공간적 특징 및 경향성 파악을 위한 719개의 사진분석결과 ‘수변산책로’, ‘거주지 주변’, ‘공원’, ‘도시/도시인프라’, ‘반려견운동장/카페’ 총 다섯 가지 분류체계 항목으로 조사되었 다. 사진들의 다양한 요소 및 특성(Attributes) 분석틀에 의한 유형분류 결과 반려견만을 집중하여 확대, 촬영한 사진들을 제외하고 ‘경관’, ‘자연요소’, ‘활동/레저’, ‘사람’, ‘도시/장소’의 다섯 유형 으로 분류되었다. 본 연구를 통해 반려견 산책 선호장소와 유형들을 파악하여 반려견 산책환경 개 선방안을 도출하였다.

핵심정서(core affect) 이론에 따르면, 정서는 정서가(valence)와 각성가(arousal)의 독립적인 두 차원의 구성으로 이루어진다(Russell, 2003; Russell & Barrett, 1999). 기존 정서 연구에서는 정서를 유발하는 여러 시청각 자극들이 핵심정서 차원에 위치한다는 사실을 밝혀냈다. 하지만 기존 연구에서 사용된 대부분의 자극은 시각과 청각에 국한되 어 있었으며, 미각 자극들을 활용한 연구는 많지 않았다. 이에 본 연구에서는 정서유발 자극으로서 미각 자극을 활용 하여 유발된 정서가 미각 자극의 속성에 따라 핵심정서 차원에 표상되는지 알아보고자 하였다. 실험 자극으로 실생 활에서 접할 수 있는 식품들을 4가지 기본 맛 유형(단맛, 쓴맛, 신맛, 그리고 짠맛), 그리고 2가지 맛의 강도 설계로 자극을 선정하였다. 참가자들에게 각 자극을 제시하고, 자극에 대한 맛 평정과 참가자가 느낀 정서를 평정하도록 하였다. 수집된 자료는 일변량분석방법인 반복측정변량분석과 다변량분석방법인 다차원척도법(multidimensional scaling) 및 분류분석(classification)으로 분석하였다. 변량분석 결과, 참가자들은 단맛을 지각할수록 긍정적인 정서 를, 쓴맛 혹은 짠맛을 지각할수록 부정적인 정서를 경험하였다. 각성가 결과에서는 맛의 강도가 강할수록 더 높은 각성 경험이 보고되었다. 다차원척도법 분석 결과, 1차원에서 단맛 대 쓴맛 그리고 짠맛 대비를, 2차원에서 쓴맛과 짠맛 구분을 확인하였다. 벡터 피팅 결과는 핵심정서이론의 설명대로 1차원이 정서가, 2차원이 각성가 차원으로 구 성되었음을 지지하였다. 분류분석 결과 참가자들의 정서 반응을 통해 미각 자극의 맛 유형을 유의미하게 예측할 수 있었다. 본 연구의 결과는 미각 자극도 자극 속성에 따라 핵심정서차원에 위치한다는 것을 시사한다.

Discontinuities exert great influence on the thermal, hydraulic, and mechanical behavior of rock mass. Rock joint is one of the most frequently encountered discontinuities in many engineering applications, such as tunnel, rock slope and repository for high level radioactive waste. Therefore, the effects of rock joint should be thoroughly investigated in various aspects. Rock joint has gone through many geological processes and its behavior can be characterized by many properties. Among them, geometric properties, such as joint roughness, aperture, and contact area can affect mechanical and hydraulic properties and vice versa. Therefore, accurate understanding and characterization of the geometric properties are of importance. Generally, the geometric properties of a joint are obtained or estimated using the surface height or elevation, which could be measured by various contact or noncontact methods. Then, the coordinates of the surfaces are used to calculate several parameters, for instance roughness indexes and mechanical aperture, in a quantitative manner. This paper is a part of SKB task force project that aims to evaluate the geometric properties of rock joints and to analyze the hydromechanical behavior within a rough joint considering the properties. Four pairs of joint surfaces were laser-scanned in order to obtain coordinates of the surfaces and then the coordinates were used to calculate the roughness, directional roughness, aperture, and spatial correlations. At the same time, fluid flow within a rough joint were simulated by a commercial FEM code, considering the variation of aperture space due to normal load. Flowrate, flow path, and channelization were investigated in an aperture scale. Since rock mass consists of several joints and/or joint sets, characterization of a single rock joint can be utilized for analyzing the behavior of rock mass as a reference.

The nuclear criticality analyses considering burnup credit were performed for a spent nuclear fuel (SNF) disposal cell consisting of bentonite buffer and two different types of SNF disposal canister: the KBS-3 canister and small standardized transportation, aging and disposal (STAD) canister. Firstly, the KBS-3 & STAD canister containing four SNFs of the initial enrichment of 4.0wt% 235U and discharge burnup of 45,000 MWD/MTU were modelled. The keff values for the cooling times of 40, 50, and 60 years of SNFs were calculated to be 0.79108, 0.78803, and 0.78484 & 0.76149, 0.75683, and 0.75444, respectively. Secondly, the KBS-3 & STAD canister with four SNFs of 4.5wt% and 55,000 MWD/MTU were modelled. The keff values for the cooling times of 40, 50, and 60 years were 0.78067, 0.77581, and 0.77335 & 0.75024, 0.74647, and 0.74420, respectively. Therefore, all cases met the performance criterion with respect to the keff value, 0.95. The STAD canister had the lower keff values than KBS-3. The neutron absorber plates in the STAD canister significantly affected the reduction in keff values although the distance among the SNFs in the STAD canister was considerably shorter than that in the KBS-3 canister.

There is an ever growing interest in the development of biochar from a large variety of agrowastes. Herein, the main objective is the conversion of pomegranate peel powder biochar and its post-functionalization by phosphoric acid treatment, followed by arylation organic reaction. The latter was conducted using in situ-generated diazonium salts of 4-aminobenzoic acid ( H2N-C6H4-COOH), sulfanilic acid ( H2N-C6H4-SO3H) and Azure A dye. The effect of diazonium nature and concentration on the arylation process was monitored using thermal gravimetric analysis (TGA) and Raman spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). SEM pictures showed micrometer-sized biochar particles with tubular structure having about 10–20 μm-wide channels. SEM studies have shown that arylation did not affect the morphology upon arylation. The porous structure did not collapse and withstood the arylation organic reaction in acid medium did not collapse upon arylation. TGA and Raman indicated gradual changes in the arylation of biochar at initial concentrations 10– 5, 10– 4 and 10– 3 mol L− 1 of 4-aminobenzoic acid. The detailed Raman spectra peak fittings indicate that the D/G peak intensity ratio leveled off at 3.35 for 4-aminobenzoic acid initial concentration of 10– 4 mol L− 1, and no more change was observed, even at higher aryl group mass loading. This is in line with formation of oligoaryl grafts rather than the grafting of new aryl groups directly to the biochar surface. Interestingly, Azure A diazonium salt induced much lower extent of surface modification, likely due to steric hindrance. To the very best of our knowledge, this is the first report on diazonium modification of agrowaste-derived biochar and opens new avenues for arylated biochar and its applications.

Recently, the deep geological disposal system isolating a spent nuclear fuel (SNF) is considered a disposal method of high-level radioactive waste for the safety of humans or the natural environment. The one of important requirements for maintaining the thermal stability of these systems is that the temperature of the buffer does not exceed 100°C even though the decay heat is emitted from highlevel radioactive wastes loaded in the disposal container. In 2007, a deep geological disposal system based on the Swedish disposal concept was developed for the SNF in Korea. To respond to the development process, the thermal stability of the deep geological disposal system developed for the disposal of domestic pressurized light water reactor (PWR) SNFs with discharged burn-up of 55 GWD/MTU was evaluated in 2019. The thing is that the recent fuel activity is pursuing to operate further high burn-up fuel conditions, and it leads to emergency core cooling system (ECCS) revision for extending the license for up to 60 or more than 60 GWD/MTU in the world. In this regard, this study evaluates numerically the thermal stability of the deep geological disposal system for the high burn-up PWR SNF having large decay heat compared to previous conditions for two different length disposal containers classified according to the length of PWR SNFs discharged from domestic nuclear power plants. A finite element analysis using a computational program was used to evaluate the thermal design requirements. Results show that both types of disposal containers would increase the temperature which reduces or fails to meet the safety margin of the disposal system. This study suggests that the design of the previous disposal system is needed to be further developed for the high burn-up PWR SNF which would be used in future nuclear power plant systems.

In the design of a spent-fuel (SF) storage, the consideration of burnup credit brings the benefits in safety and economic views. According to it, various SF burnup measurement systems have been developed to estimate high fidelity burnup credit, such as FORK and SMOPY. Recently, there are a few attempts to localize the SF burnup measurement system in South Korea. For the localization of SF burnup measurement systems, it is very important to build the isotope inventory data base (DB) of various kinds of SFs. In this study, we performed DeCART2D/MASTER core follow calculations and McCARD single fuel assembly (FA) burnup analyses for Hanbit unit 3 and confirmed the characteristic of the isotope inventory over burnup. Firstly, the core follow calculations for Cycles 1~7 were performed using DeCART2D/MASTER code system. The core follow calculation is very realistic and practical because it considers the design conditions from its nuclear design report (NDR). Secondly, the Monte Carlo burnup analyses for single FAs were conducted by the McCARD Monte Carlo (MC) transport code. The McCARD code can utilize continuous energy cross section library and treat complex geometric information for particle transport simulation. Accordingly, the McCARD code can provide accurate solutions for burnup analyses without approximations, but it needs huge computing resources and time burden to perform whole-core follow calculations. Therefore, we will confirm the effectiveness of the single McCARD FA burnup analyses by comparing the DeCART2D/MASTER core follow results with the McCARD solution. From the results, the use of single FA burnup analyses for the establishment of the DBs will be justified. Various FAs, that have different 235U enrichments and loading pattern of fuel rods and burnable absorbers, were considered for the burnup analyses. In addition, the results of the sensitivity analyses for power density, initial enrichment, and cooling time will be presented.

Even though it is emphasized to apply safeguards-by-design (SBD) concept in the early phase of the design of a new nuclear facilities, there is no clear guideline or tools for the practical SBD implementation. Generally known approach is trying to review whether there is any conflicts or shortcomings on a conceptual safeguards components in a design information. This study tries to build a systematic tools which can be easily applied to safeguards analysis. In evaluating the safeguards system or performance in a facility, it is essential to analyze the diversion path for nuclear materials. Diversion paths, however, can be either extremely simplified or complicated depending on the level of knowledge and purpose of specific person who do analyze in the field. In the context, this study discusses the applicability of an event tree and fault tree method to generating diversion paths systematically. The essential components constituting the diversion path were reviewed and the logical flow for systematically creating the diversion path was developed. The path generation algorithm based on the facility design components and logical flow as well as the initial information of the nuclear materials and material flows was test using event tree and fault tree analysis tools. The usage and limitation of the applicability of this two logic methods are discussed and idea to incorporate the logic algorithm into the practical program tools is suggested.The results will be used to develop a program module which can systematically generate diversion paths using the event tree and fault tree method.

천수만과 태안해역의 제한영양염을 평가하기 위해 장기자료 분석과 생물검정실험을 진행하였다. 우선 잠재적인 제한영양염을 평가하기 위해 국가수질측정망에서 제공되는 2004~2016년 동안의 장기 영양염 자료를 이용하였다. 장기자료의 DIN/DIP를 분석한 결과 대 부분 16이하로 N 제한이 우세하였지만 N, P, Si의 농도비를 이용한 분석에서는 하계와 추계에는 N 제한이 우세하였고, 동계와 춘계에는 해역에 따라 일부 Si 제한을 보이거나 또는 제한이 나타나지 않았다. 생물검정실험 시 채집된 현장수의 영양염 분석결과, DIN/DIP는 3월 과 5월에 모든 정점에서 P 제한을 나타냈고, 7월과 10월에는 N 제한이 우세하였다. N, P, Si의 농도비를 이용한 분석에서 3월과 5월은 P와 Si 제한을 보이거나 제한영양염이 나타나지 않은 정점이 존재하였으나 7월과 10월에는 N 제한이 우세하였다. 실질적인 제한영양염을 평 가하기 위해 수행된 생물검정실험 결과 3월에는 특정 제한영양염이 나타나지 않았으나, 5월, 7월 10월에는 NH4 +와 NO3 -가 반응을 보임으 로서 이 시기에는 N이 식물플랑크톤 성장에 직접 관여하는 실질적인 제한영양염임을 확인하였다.