We study quasi-spherical, supersonic accretion flows around black holes using high-accuracy numerical simulations. We describe a code, the Lagrangian Total Variation Diminishing (TVD), and a remap routine to address a specific issue in the Advection Dominated Accretion Flow (ADAF) that is, appropriately handling the angular momentum even near the inner boundary. The Lagrangian TVD code is based on an explicit finite difference scheme on mass-volume grids to track fluid particles with time. The consequences are remapped on fixed grids using the explicit Eulerian finitedifference algorithm with a third-order accuracy. Test results show that one can successfully handle flows and resolve shocks within two to three computational cells. Especially, the calculation of a hydrodynamical accretion disk without viscosity around a black hole shows that one can conserve nearly 100% of specific a ngular momentum in one-and twodimensional cylindrical coordinates. Thus, we apply this code to obtain a numerically similar ADAF solution. We perform simulations, including viscosity terms in one-dimensional spherical geometry on the non-uniform grids, to obtain greater quantitative consequences and to save computational time. The error of specific angular momentum in Newtonian potential is less than 1% between r~10rs and r~10 4 rs, where rs is sink size. As Narayan et al. (1997) suggested, the ADAFs in pseudo-Newtonian potential become supersonic flows near the black hole, and the sonic point is rsonic~5.3rg for flow with α =0.3 and  =1 .5. Such simulations indicate that even the ADAF with  =5/3 is differentially rotating, as Ogilvie (1999) indicated. Hence, we conclude that the Lagrangian TVD and remap code treat the role of viscosity more precisely than the other scheme, even near the inner boundary in a rotating accretion flow around a nonrotating black hole.

안전은 해군과 같은 위험성이 높은 환경에서 활동하는 조직에게 필수적이다. 효과적인 안전관리는 지속적인 개선과 보완을 통 해 유지되어야 하며, PDCA cycle을 활용하는 것이 일반적이다. 하지만 해군에서는 안전 규정 강화와 교육 확대에도 불구하고 안전사고가 지속적으로 발생하고 있다. 이는 안전사고 분석 및 분류 시스템 개선의 필요성을 보여준다. 본 연구에서는 해군 안전사고 분류체계를 분 석하고 문제점을 파악하여 효과적인 분류체계를 구축하는데 중점을 두었다. 이를 통해 안전사고 결과를 데이터화하고, 사고의 근본 원인 을 파악하며, 중장기적인 안전관리 정책 수립에 기여할 수 있도록 12자리의 해군 안전사고 분류 코드를 제안하였다.

In the military, ammunition and explosives stored and managed can cause serious damage if mishandled, thus securing safety through the utilization of ammunition reliability data is necessary. In this study, exploratory data analysis of ammunition inspection records data is conducted to extract reliability information of stored ammunition and to predict the ammunition condition code, which represents the lifespan information of the ammunition. This study consists of three stages: ammunition inspection record data collection and preprocessing, exploratory data analysis, and classification of ammunition condition codes. For the classification of ammunition condition codes, five models based on boosting algorithms are employed (AdaBoost, GBM, XGBoost, LightGBM, CatBoost). The most superior model is selected based on the performance metrics of the model, including Accuracy, Precision, Recall, and F1-score. The ammunition in this study was primarily produced from the 1980s to the 1990s, with a trend of increased inspection volume in the early stages of production and around 30 years after production. Pre-issue inspections (PII) were predominantly conducted, and there was a tendency for the grade of ammunition condition codes to decrease as the storage period increased. The classification of ammunition condition codes showed that the CatBoost model exhibited the most superior performance, with an Accuracy of 93% and an F1-score of 93%. This study emphasizes the safety and reliability of ammunition and proposes a model for classifying ammunition condition codes by analyzing ammunition inspection record data. This model can serve as a tool to assist ammunition inspectors and is expected to enhance not only the safety of ammunition but also the efficiency of ammunition storage management.

Abstract Purpose : This study sought to find ways to improve awareness and ethics of opticians' code of ethics. Methods : A survey was conducted on 102 Korean opticians to investigate the awareness and performance satisfaction of the optician's code of ethics, as well as differences according to gender, age, education level, work experience, and workplace. Results : This study found no gender-based differences in opticians’ awareness and satisfaction with the code of ethics. However, age and education significantly influenced these factors, with higher levels observed among opticians in their 20s and 30s, particularly those in the early stages of their careers. Furthermore, a positive correlation was noted between education level and both awareness and satisfaction. The study revealed that opticians with volunteer experience exhibited higher awareness and satisfaction with the code of ethics than those without. This suggests that volunteering, which fosters professional identity and social responsibility, influences opticians’ ethical awareness. Additionally, groups with a strong interest in foreign languages and self-development demonstrated higher ethical awareness and satisfaction. Conclusion : This study underscores the need for enhanced ethical awareness among opticians. It advocates for the development of methods, case studies, and guidelines to address ethical issues not covered by the existing code, thereby revitalizing ethical practices in the profession. In addition, it is judged that active promotion and education on the code of ethics and professional ethics are necessary for the continuing education of opticians. Key words : Awareness, Code of ethics, Performance satisfaction

BIM에서 가장 중요한 요소 중의 하나가 디지털 데이터이다. 체계적인 디지털 데이터 관리를 위해 최근까지 연구를 통해 객체분류 체계(OBS)와 속성분류체계(Pset)가 제시되어 왔다. 특히 공정 및 기성 관리에 사용되는 디지털 데이터는 WBS와 CBS로 나뉘고 이를 BIM 객체와 매핑하려면 CBS의 수량 분개가 필요한데 CBS는 양이 매우 방대하고 공종이나 규격, 명칭 및 CBS 코드가 발주처마다 상 이하여 WBS나 BIM 모델에 맞는 수량 분개 작업을 엑셀 등을 이용해서 수작업으로 한다는 것은 사실상 어렵다. 이러한 문제점을 극복 하기 위해 BIM 모델에 의해 산출하기 힘든 수량 중에서 대부분을 차지하는 연장에 근거한 수량의 전체분을 분개하는 방안, 축적된 WBS-CBS 이력으로부터 최적 CBS를 도출하는 방안과 합리적인 CBS 데이터베이스 구축을 위해 필수적인 CBS 코드 통합 표준화 방 안을 제시하였다.

In 2017, the permanent shutdown of Kori Unit 1 was decided, marking the initiation of preparations for the decontamination and decommissioning of Kori Unit 1. The dismantling of radiologically contaminated equipment and concrete structures such as the Reactor Vessel (RV), Reactor Vessel Internals (RVI), and the Bio shield is crucial in the nuclear decommissioning process. These components became radiologically contaminated due to nuclear fission reactions occurring in the reactor during its operational period. The RVI dismantling at Spain’s Jose Cabrera Nuclear Power Plant involved the use of mechanical saws and disk cutters to divide it into approximately 430 pieces, taking 16 months to complete. Germany’s Stade Nuclear Power Plant employed mechanical circular saws to segment their RVI into about 170 pieces, which took 30 months to accomplish. Meanwhile, the RVI at Germany’s Wurgassen Nuclear Power Plant was subdivided into approximately 1,200 pieces using a combination of mechanical saws and abrasive water jets, requiring 61 months for completion. Due to the radioactivity in Kori Unit 1’s Reactor Vessel (RV) and Reactor Vessel Internals (RVI), remote-controlled systems were developed for cutting within the cavity to reduce radiation exposure. Specialized equipment was developed for underwater cutting operations. This paper focuses on modeling related to RVI operations using the MAVRIC code. The upper and lower parts of the RVI are classified as low-level radioactive waste, while the sides of the RVI that come into contact with fuel are classified as intermediate-level radioactive waste. Therefore, the modeling presented in this paper only considers the RVI sides since the upper and lower parts have a minimal impact on radiation exposure. Accurate calculations were performed through geometric modeling and radiation dose modeling. These research findings are anticipated to contribute to enhancing the efficiency and safety of nuclear reactor decommissioning operations

For the release of the nuclear power plant site after the decommissioning, a reliable exposure dose assessment considering the environmental impact of residual radionuclides is essentially required. In this study, the Derived Concentration Guideline Level (DCGL) for the hypothetically contaminated surface soil at the Wolsong nuclear power plant (NPP) unit 1 site was preliminarily calculated by using the RESRAD-OFFSITE computational code and compared with the other case studies. Moreover, radiation exposure dose for local residents and relevant exposure pathways were quantitatively analyzed based on the calculation model established through this work. For the target site modeling, the source term was determined by referring to the previous case studies regarding the nuclear power plant decommissioning, quantification analysis data of pressure tubes of Wolsong NPP unit 1, and radionuclide data estimated by using the MCNP/ORIGEN-2 code. In total, 14 different radioisotopes such as Ag-108m, C-14, Co-60, Cs-134/137, Fe-55, H-3, Nb-93m/94, Ni-63, Sb-125, Sn-121m, Sr-90, and Zr-93 were considered as target radionuclides. In addition, the geological structure model of the Wolsong NPP site was established based on the final safety analysis report of Wolsong NPP unit 1. The distribution coefficients (Kd) were taken from the JAEA-SDB to estimate the migration/retardation behavior of various radionuclides under the groundwater condition of the Wolsong NPP site. In the present work, the DCGL values were calculated according to the site release criterion of 0.1 mSv/yr, which indicates the radiation protection standard for the site release. Moreover, the exposure pathway and sensitivity analyses were conducted to assess the sensitive input parameters remarkably influencing the calculation result. For the evaluation of exposure dose for local residents, a site layout centered around Wolsong NPP unit 4, located in the closest proximity to the residents’ habitation area, was alternatively established and all potential exposure pathways were considered as a comprehensive resident farmer scenario. The results obtained from this study are expected to serve as a preliminary case study for the DCGL values regarding the surface soil at the Wolsong NPP unit 1 site and for evaluating the radiation exposure dose to local residents resulting from the residual radioactivity at the site after the decommissioning.

The HADES (High-level rAdiowaste Disposal Evaluation Simulator) was developed by the Nuclear Fuel Cycle & Nonproliferation (NFC) laboratory at Seoul National University (SNU), based on the MOOSE Framework developed by the Idaho National Laboratory (INL). As an application of the MOOSE Framework, the HADES incorporates not only basic MOOSE functions, such as multi-physics analysis using Finite Element Method (FEM) and various solvers, but also additional functions for estimating the performance assessment of Deep Geological Repositories (DGR). However, since the MOOSE Framework does not have complex mesh generation and data analyzing capabilities, the HADES has been developed to incorporate these missing functions. In this study, although the Gmsh, finite element mesh generation software, and Paraview, finite element analysis software, were used, other applications can be utilized as well. The objectives of HADES are as follows: (i) assessment of the performance of a Spent Nuclear Fuel (SNF) disposal system concerning Thermal-Hydraulic-Mechanical-Chemical (THMC) aspects; (ii) Evaluation of the integrity of the Engineered Barrier System (EBS) of both general and high-efficiency design perspective; (iii) Collaboration with other researchers to evaluate the disposal system using an open-source approach. To achieve these objectives, performance assessments of the various disposal systems and BMTs (BenchMark Test), conducted as part of the DECOVALEX projects, were studied regarding TH behavior. Additionally, integrity assessments of various DGR systems based on thermal criteria were carried out. According to the results, HADES showed very reasonable results, such as evolutions and distributions of temperature and degree of saturation, when compared to validated code such as TOUGH-FLAC, ROCMAS, and OGS (OpenGeoSys). The calculated data are within the range of estimated results from existed code. Furthermore, the first version of the code, which can estimate the TH behavior, has been prepared to share the contents using Git software, a free and open-source distribution system.

Dry storage of nuclear fuel is compromised by threats to the cladding integrity, such as creep and hydride reorientation. To predict these phenomena, spent fuel simulation codes have been developed. In spent fuel simulation, temperature information is the most influential factor for creep and hydride formation. Traditional fuel simulation codes required a user-defined temperature history input which is given by separate thermal analysis. Moreover, geometric changes in nuclear fuel, such as creep, can alter the cask’s internal subchannels, thereby changing the thermal analysis. This necessitates the development of a coupled thermal and nuclear fuel analysis code. In this study, we integrated the 2D FDM nuclear fuel code GIFT developed at SNU with COBRA -SFS. Using this, we analyzed spent nuclear stored in TN-24P dry storage cask over several decades and identified conditions posing threats due to phenomena like creep and hydrogen reorientation, represented by the burnup and peak cladding temperature at the start of dry storage. We also investigated the safety zone of spent nuclear fuel based on burnup and wet storage duration using decay heat.

Spent nuclear fuels should be safely stored until being disposed and dry storage system is predominantly used to retain the fuels. Thermal analysis to estimate temperatures of spent nuclear fuel and the storage system should be performed to evaluate whether the temperatures exceed safety limit. Recently, thermal hydraulic analysis with CFD codes is widely used to investigate the temperature of spent nuclear fuel in dry storage. COBRA-SFS is a legacy code based on subchannel analysis code, and its fidelity is verified for evaluating the thermal analysis for licensing a dry cask system. Herein, thermal analysis result based on CFD and COBRA-SFS codes is compared and the Dry Cask Simulator (DCS) is assessed as a benchmark experiment in this study. Extended Storage Collaborating Program (ESCP) led by the Electric Power Research Institute (EPRI) is organized to address the degradation effects of spent nuclear fuel during long-term dry storage, and DCS is the first phase of the program. The dry storage system, containing a single BWR assembly in a canister, was designed to produce validation-quality data for thermal analysis model. ANSYS FLUENT was used to simulate DCS. Simulations were conducted in various decay heat and helium pressure inside the canister. In realistic conditions of decay heat and helium pressure of actual dry cask system, CFD and COBRA-SFS analysis results gave good agreement with experimental measurement. Peak temperatures of channel can, basket, canister and shell predicted by CFD simulation also showed good prediction and the discrepancies were less than 7 K while measurements uncertainty was 7 K. In high decay heat and high pressure condition, however, CFD and COBRA-SFS underestimated peak cladding temperature than experimental results.

본 연구에서는 BTS의 노래가사 언어 코드 비율 변화와 트위터 내 팬 덤 아미(ARMY)의 메타언어적 코멘트를 통해 BTS 현상에서의 언어 이 데올로기를 탐구하였다. 분석대상은 2013년부터 2022년까지 BTS의 앨 범에 포함된 121곡의 노래이다. 연구결과, 영어 코드 선택 비율은 꾸준 히 증가하여 2013년 21.2%에서 2022년에는 57.5%까지 상승하였으며, 반면에 한국어 코드 선택 비율은 2013년 78.8 %에서 점차 하락하여 42.5%로 감소하는 양상을 확인했다. 또한 트위터에 나타난 팬들의 메타 언어 코멘트를 분석한 결과, 언어 민족주의적 순수주의의 태도와 반-언 어 민족주의적 순수주의의 태도가 대립하는 형태를 관찰하였다. 언어 민 족주의적 순수주의의 태도를 가진 팬들은 한국어 사용을 한국적 정체성 의 실현으로 연결 짓고, 영어 코드의 증가를 우려하는 경향을 보였다. 한 편, 반-언어 민족주의적 순수주의의 태도를 가진 팬들은 BTS의 언어 코 드 선택과 정체성의 연결을 지양하며, 언어 코드 선택에 대한 비판에 저항하는 모습을 보였다. 이러한 연구결과를 바탕으로 BTS는 적절한 언 어 코드를 사용하여 글로벌 팬들과 소통함으로써 다양성과 포용성을 장 려하고, 팬덤 "아미"는 언어 선택 행위에 대한 이해와 존중을 확대함으로 써 언어 이데올로기에 대한 인식을 높일 수 있는 방안을 제공하였다는 점에서 의의가 있다.

This paper presents a study on the design and implementation of a secure contactless system leveraging Quick Response (QR) codes as a core component. The main goal of this system is to bridge the gap between strong security and improved user experience within the realm of digital interaction. The system's versatility can be expanded with broad compatibility with a variety of applications. Utility can be expanded to areas such as contactless payments, electronic ticketing, secure identity verification, and convenient access to medical records. The international standardization of QR codes ensures seamless cross-platform compatibility, strengthening their role in the digital ecosystem. We actually create and develop a non-contact security QR code system and check the expandability of the system. This study highlights the pivotal role of QR codes within the realm of secure contactless systems. Through its effective balance of digital security and user convenience, QR codes are emerging as an important element in the continued development of a secure and user-friendly digital environment. The potential for future research lies in exploring more complex use cases and further advancements that improve both security and user-centered design.

In the event of a loss of a SNF (spent nuclear fuel) transport cask during maritime transportation, it is essential to evaluate the critical depth at which the integrity of the cask can be maintained under high water pressure. SNF transport casks are classified as Type B containers and the integrity of of the containment boundary must be maintained up to a depth of 200 meters unless the containment boundary was breached under beyond-design basis accidents. However, if an intact SNF cask is lost at a depth deeper than 200-meter, release of radioactive material may occur due to breach of containment boundary with over-pressure. In this study, we developed a code for the evaluation of the pressure limit of SNF transport cask, which can be evaluated by inputting the main dimensions and loading conditions of cask. The evaluation model was coded as a computer module for ease of use. In the previous study, models with three different fidelities were developed to ensure the reliability of the calculation and maintain sufficient flexibility to deal with various input conditions. Those three models consisted of a high-fidelity model that provided the most realistic response, a low-fidelity model with parameterized simplified geometry, and a mathematical model based on the shell theory. The maximum stress evaluation of the three models confirmed that the mathematical model provides the most conservative results than the other two models. The previous results demonstrate that mathematical models can be used in the code of computer modules. In this study, additional models of transport cask were created using parametric modeling techniques to improve the accuracy of the pressure limit assessment code for different cask and situations. The same boundary conditions and loading conditions were imposed as in the previous simplified model, and the maximum stress results considering the change in the shape of the transport container were derived and compared with the mathematical model. The comparison results showed that the mathematical model had more conservative values than the simplified model even under various input conditions. Accordingly, we applied the mathematical model to develop a transportation container pressure limit evaluation code that can be simulated in various situations such as shape change and various situations.

본 연구는 東晉의 王羲之(303-361)가 쓰고 宋人(米芾(1051-1107)로 추정)이 편찬한『草訣 百韻歌』에서 시작한다. 기존 歌訣 해설과 다르게 본 연구는 전통 이론과 실제 붓을 잡고 쓴 경험을 바탕으로, 宋人이 가결을 통해 후학에게 전달하고자 했던 초서의 요체를 새롭게 밝히고 자 한다. 이로써 전통 이론 중, 초서에게 부여된 ‘積其點畫, 乃成其字’, ‘草以點畫為情性, 使轉 為形質’과 같은 간단명료한 원칙의 의미를 더욱 깊이 있게 이해할 수 있을 것이다. 또한, 초서 문자 구조에 잠재된 변화규칙과 초서의 ‘連綿’, ‘游絲’의 추론과 설명 방식을 고찰할 것이다. 이는 초서 문자의 해독과 초서 문헌의 이해할 수 있게 한다는데 의의가 있다. 본 연구의 방법 및 과정은 크게 4가지로 구분된다. (1) 『草訣百韻歌』 중 간략하게 서술된 초서 변화의 요체를 해석하고, 점을 찍는 것에서부터 선을 연결하고 문자를 구성하는 기본 ‘結字 法’을 상세하게 분석한다. ‘圓筆’, ‘潤筆’, ‘渴筆’, ‘轉筆’ 등의 필법이 포함되며, ‘楷’에서 ‘草’로 전개되는 과정에서 문자의 틀과 필획의 구조 변화도 설명한다. (2) 초서에서 가로획과 세로획의 교차 운용 법칙을 상세하게 분석하고, 나아가 ‘撇捺改筆’, ‘戈法變換’ 등 획과 선의 배치, 한자 구조의 변화 등도 아울러 분석하고 논한다. 이는 초서 쓰기, 읽기, 이해에 이론적이고 과학적 해결법을 제공할 것이다. (3) 초서 章法의 기본을 해석하고 초서 필획 중 虛･實의 분배와 운용 및 ‘計白當黑’, ‘意連形連’과 같은 필획 구성의 요체를 고찰한다. (4) ‘連綿’을 재구조화하고, 초서의 점과 획의 변화 규칙을 활용하여 ‘連綿’, ‘游絲’의 필법 원리를 해석한다. 또한 고문헌의 해석에 응용하여 ‘龍蛇競筆端’에 포함된 초서로 쓰인 한자의 수수께끼를 풀어낼 것이며, 이로써 초서 筆法字學 학습의 중요성과 그 가치를 밝힌다.