인터넷과 빅데이터 시대에 혼돈을 기반으로 한 디지털 영상암호화 알고리즘에 대한 연구는 정보보안 분야 의 연구 핫스팟 중 하나가 되었다. 기존의 텍스트 데이터에 비해 디지털 이미지는 데이터의 양이 많고 중복 성이 높은 특성을 가지고 있습니다. DES, AES 및 RSA와 같은 기존 방법은 디지털 이미지 암호화 요구 사 항을 충족할 수 없습니다. 초기 민감도와 고유한 임의성 때문에 카오스는 암호화의 혼란 및 확산 개념과 매 우 일치하므로 카오스 이미지 암호화에 대한 연구가 빠르게 발전했습니다. 본 논문에서는 주로 혼돈 영상 암호화에 대한 연구를 수행한다. 평문 영상에 대한 키 의존성을 목표로 비트 평면과 개선된 로지스틱 맵 기 반 영상 암호화 알고리즘을 제안한다. 알고리즘은 스크램블된 일반 텍스트 이미지의 낮은 4비트 비트 매트 릭스를 개선된 물류 맵의 제어 매개변수로 사용하여 일반 텍스트 이미지에 대한 키의 종속성을 높이고 놀 라운 일회성 비밀 특성을 갖습니다. 서로 다른 비트의 이미지 정보에 따라 서로 다른 강도의 암호화 알고리 즘을 설계하여 알고리즘의 효율성을 높입니다. 영상 암호화의 확산 모드를 목표로 하이퍼 카오스 시스템과 블록 모듈로 기반의 영상 암호화 알고리즘을 제안한다. 알고리즘은 하이퍼 카오스 시스템을 사용하여 카오 스 시퀀스를 반복적으로 생성하고, 암호화된 픽셀 주위에 임의의 이미지 블록을 분할하고, 블록의 픽셀 값 에 대해 적분 모듈로 연산을 수행하여 암호화된 픽셀 회색 값을 얻음으로써 확산 범위를 효과적으로 확장 하고 확산의 무작위성을 향상시킵니다.

1970년대 이후 게임시장 규모의 폭발적 성장과 함께 하드웨어의 발전을 바탕으로 온라인 게임의 성장을 비 롯하여 게임 규모는 지속적으로 확장하고 있다. 대규모 자본과 인력이 투입된 이른바 AAA게임은 게임의 시장규모를 증가시킨 순기능 이외에 게임플레이의 획일화를 가져온 역기능으로도 작용하게 되었다. 이러한 시장의 반대측면에서 소규모 또는 1인 개발자들에 의해 개발되는 인디게임이 차츰 주목받고 성장하고 있 는 추세에 있다. 특히 ‘마인크래프트’의 성공 이후에 인디게임 업계로 진입하는 소규모 게임 개발자와 1인 게임 개발자들의 양도 동반 증가하였으며, 이들은 AAA게임이 가지지 못한 독특한 아이디어와 디자인 요소 를 활용하고, 크라우드 펀딩 등의 방법을 통해 자금을 조달하는 제작 형태를 띄고 있다. 인디게임은 2022년 현재 게임 플랫폼 ‘스팀’에 등록된 게임수가 40043개에 이를 정도로 지속적인 시장 확대를 이루고 있으나 최근, 스폰서와 대규모 투자를 바탕으로 한 인디게임 개발의 추세에 힘입어 소규모 또는 1인 인디게임 개 발자들의 경쟁력은 낮아지고 있다. 본 연구에서는 2020년부터 2022년까지 ‘인디게임‘ 키워드를 바탕으로 빅 데이터 분석방법을 통하여 인디게임 산업의 이슈를 추출하고 이슈와 관련한 게임의 현황과 향후 인디게임 방향성을 밝혀보고자 하였다. 연구의 결과로 2020년의 인디게임 플랫폼의 보급과 함께 시장이 확장되는 것 을 알 수 있으며, 2021년은 인디게임 보급을 뒷받침 할 수 있는 지원정책이 확산되는 현상을 파악할 수 있 었다. 2022년은 다양한 해외 플랫폼을 바탕으로 지원정책에 힘입어 지속적으로 제작되고 있으며 해외진출 을 시도함과 동시에 인디게임 산업의 활성화를 위한 육성정책이 이루어지고 있음을 알 수 있다.

본 연구에서는 액체감쇠역전회복(FLAIR) 시퀀스를 대체하였던 방법 중에 비교적 간단하면서 높은 재현성을 나타내었던 고신호 강도제거 원리를 MAGiC에 적용하여 MAGiC-FLAIR와 기존의 고속스핀에코-FLAIR 영상과 비교하여 고신호 강 도제거영상의 유용성과 임상적으로 유의미한 기준을 제시하고자 하였다. 연구방법은 MAGiC 적용 후 MAGiC-FLAIR와 MAGiC-고신호 강도제거 영상을 재구성하여, 기존의 고속스핀에코-FLAIR 영상과 각각 정성적, 정량적 평가를 비교하였 다. 정성평가결과 MAGiC-고신호 강도제거는 MAGiC-FLAIR 보다는 월등히 우수하며, 고속스핀에코-FLAIR와 유사한 결과를 보였고, 정량평가결과 MAGiC-고신호강도제거는 MAGiC-FLAIR보다 백질과 회백질 대조도는 더 우수할 뿐만 아 니라, 뇌척수액의 신호 억제도 우수한 결과를 나타냈다. Synthetic 영상을 통하여 획득한 다양한 대조도 영상 중 FLAIR의 부정확도를 고신호 강도제거기법을 적용한다면 진단적 가치를 개선하여 제공할 수 있을 것이다.

The Act on the Punishment of Serious Accidents to Prevent Large-scale Disasters, including Ferry Sewol and Taean Thermal Power Plant, passed the National Assembly on January 8, 2021, and has been in effect since January 27, 2022. However, the law, in which the representative of the headquarters is unlimitedly responsible for each worker's accident, is somewhat unreasonable at a time when a company owns dozens to hundreds of construction sites due to the nature of the construction industry. I agree with the purpose of enacting the law to reduce chronic serious accidents at construction sites, but it is necessary to carefully reconsider the implementation of the law in that punishment alone cannot achieve industrial safety. Previous studies focused on revising the Occupational Safety and Health Act, but there are few studies on the impact on the construction industry after the implementation of the Serious Accident Act. Therefore, this study attempts to derive problems related to the application of the Serious Accident Act and present improvement measures. To this end, after analyzing previous studies, SWOT analysis was performed by applying the Delphi method to derive strengths, weaknesses, opportunities, and threats. In addition, the results of two surveys of safety experts such as public institutions, academia, and companies were reflected, and its countermeasures were presented as follows. S/O strategy: establishing on-site execution capabilities of health and safety management system; W/O strategy: expanding legal and system execution checks; S/T strategy: establishing a risk response system; W/T strategy: expanding consulting by external specialized institutions

While the use of metadiscourse in L2 writing has received considerable attention in the past, little effort has been made to examine how L2 writers’ use of metadiscourse in academic writing has evolved over time. In addressing this, the present study explored a diachronic evolution of interactional metadiscourse in research articles (RAs) published across a span of 40 years (1980-2021) in English Teaching. Based on 931 articles consisting of 6.4 million words, we examined whether the use of interactional metadiscourse has changed over the past 40 years. Our findings revealed that there was a global decrease in interactional metadiscourse over the past 40 years. While the frequency and diversity of interactional metadiscourse have slightly decreased over time, the proportion of each metadiscourse category remained consistent. The study further suggests that Korean L2 scholars who publish in English Teaching tend to hedge more than they boost or use attitude markers compared to those who publish in global journals.

In this paper, we investigate the requirements of QPA(Quality Process Audit), which is a process quality audit system for secondary defense contractors, compared with those of DQMS(Defense Quality Management System). And evaluate whether the deployment of QPA meets the DQMS certification requirements through the case example of Company H. The evaluation items of QPA are composed of five categories such as Material Management, Incoming Inspection, Manufacturing Process, Product Evaluation, and Packaging Management. The QPA requirements are mainly related to the chapter 7(support) and chapter 8(operation) of DQMS standards. In this view point, QPA can be expected as an effective audit for suppliers preparing for DQMS certification. In the case example, we evaluate the results and effects of improvement due to QPA and compare it with the case of DQMS. QPA can be used as appropriate quality management standards of secondary and tertiary defense contractors and can provide the basis guidelines for the preparation of implementation steps in DQMS certification.

Two kinds of mesocarbon microbeads (MCMBs) with different chemical composition have been synthesized. The MCMBs were molded and heat treated at temperatures above 2000 °C to obtain graphite blocks. The effects of chemical composition of MCMBs on the pore morphology, carbon texture and thermal properties of the derived graphite blocks have been explored. The pore morphology was investigated by small angle X-ray scattering technique and a graphitization-induced morphology transition was observed. When the graphitic crystallite size exceeded a threshold value, the association of crystallites and migration of randomly distributed pores took place extensively. For the graphite blocks made of MCMBs which had light components with higher aromaticity value, the growth of crystallites caused a significant enhancement in thermal conductivity for the specimens. However, for the other kind of MCMBs, their light components tended to form solid porous carbon texture after graphitization, and the thermal conductivity coefficients of their graphite blocks could only increase slightly as crystallites grew. It was suggested that the thermal resistance at the granule’s boundary became noticeable in the latter case and thus the growth of thermal conductivity coefficients was prominently hindered.

Natural environmental resources are considered a prospective source of microorganisms capable of producing biocatalysts with great potential in industrial areas. Arable soil fertilized with peat moss is a habitat for various microorganisms. The present research focused on the isolation and identification of hydrolase-producing bacteria that thrive at a broad temperature range. In this study, a total of 33 strains were isolated from arable soil fertilized with peat moss (Silla Garden in Busan, South Korea). The isolated bacteria were mesophiles and thermophiles with a wide temperature range. Taxonomic identification showed that the isolated strains belonged to 2 phyla, 5 families, 10 genera, and 24 species. Subsequently, the isolated strains were screened for hydrolase (amylase, lipase, and protease) activity. All isolates possessed activity of at least one enzyme and six bacterial isolates produced combined extracellular enzymes. Diversity of soil bacteria species in the present study suggest the potential of soil bacteria in the various industrial applications.

Appropriateness of the minimum detectable activity in the analysis of gamma radionuclides is very important. This is reason determine the time factor among the conditions of the analysis when it is rationally determined has the advantage that radioactivity analysis can be performed accurately and quickly. In this study, 100 mL of an unknown sample was diluted in Marinelli Beaker 1L to obtain, review data on gamma radiation analysis results and minimum detectable activity for each measurement time. The measurement was used High Purity Germanium detector, target nuclides are Co-57, Co-58, Y-88 and Cs-137. Since the radioactivity analysis sample will be expected to be the waste subject to selfdisposal or less during the radioactive waste classification, the minimum detectable activity standard was set based on the detection of less than the permissible activity for self-disposal for each nuclide. The measurement methods were measured by classifying it into seven categories: 1000 seconds, 3600 seconds, 10000 seconds, 30000 seconds, 80000 seconds, 100000 seconds, and 150000 seconds. The radioactivity from this measurement are Co-57 2.89 Bq·g−1, Co-58 0.19 Bq·g−1, Y-88 0.20 Bq·g−1, Cs-137 0.15 Bq·g−1, the measurement results under all conditions were similar. On the other hand, the minimum detectable activity showed values above the allowable activity for self-disposal in not but Co-58 at 1000 and 3600 seconds. Only after taking the measurement time of 10000 seconds, the result was derived Co-57 0.0095 Bq·g−1, Co-58 0.0068 Bq·g−1, Y-88 0.0052 Bq·g−1, Cs-137 0.0062 Bq·g−1, which was confirmed to less than the allowable activity for self-disposal by nuclide. Reasonably determining the measurement time in gamma radionuclide analysis is a very important issue in terms of economy of time and accuracy of measurement. Although this study cannot be said to be able to determine a reasonable measurement time for all gamma radionuclide analysis, it is hoped that research on various samples will be made to contribute to the efficient measurement of gamma radioactivity.

Gamma-ray spectroscopy, which is an appropriate method to identify and quantify radionuclides, is widely utilized in radiological leakage monitoring of nuclear facilities, assay of radioactive wastes, and decontamination evaluation of post-processing such as decommissioning and remediation. For example, in the post-processing, it is conducted to verify the radioactivity level of the site before and after the work and decide to recycle or dispose the generated waste. For an accurate evaluation of gamma-ray emitting radionuclides, the measurement should be carried out near the region of interest on site, or a sample analysis should be performed in the laboratory. However, the region is inaccessible due to the safety-critical nature of nuclear facilities, and excessive radiation exposure to workers could be caused. In addition, in the case of subjects that may be contaminated inside such as pipe structures generated during decommissioning, surveying is usually done over the outside of them only, so the effectiveness of the result is limited. Thus, there is a need to develop a radiation measurement system that can be available in narrow space and can sense remotely with excellent performance. A liquid light guide (LLG), unlike typical optical fiber, is a light guide which has a liquid core. It has superior light transmissivity than any optical fiber and can be manufactured with a larger diameter. Additionally, it can deliver light with much greater intensity with very low attenuation along the length because there is no packing fraction and it has very high radiation resistant characteristics. Especially, thanks to the good transmissivity in UV-VIS wavelength, the LLG can well transmit the scintillation light signals from scintillators that have relatively short emission wavelengths, such as LaBr3:Ce and CeBr3. In this study, we developed a radiation sensor system based on a LLG for remote gamma-ray spectroscopy. We fabricated a radiation sensor with LaBr3:Ce scintillator and LLG, and acquired energy spectra of Cs-137 and Co-60 remotely. Furthermore, the results of gamma-ray spectroscopy using different lengths of LLG were compared with those obtained without LLG. Energy resolutions were estimated as 7.67%, 4.90%, and 4.81% at 662, 1,173, and 1,332 keV, respectively for 1 m long LLG, which shows similar values of a general NaI(Tl) scintillator. With 3 m long LLG, the energy resolutions were 7.92%, 5.48%, and 5.07% for 662, 1,173, and 1,332 keV gamma-rays, respectively.

In this study, the positions of Cs-137 gamma ray source are estimated from the plastic scintillating fiber bundle sensor with length of 5 m, using machine learning data analysis. Seven strands of plastic scintillating fibers are bundled by black shrink tube and two photomultiplier tubes are used as a gamma ray sensing and light measuring devices, respectively. The dose rate of Cs-137 used in this study is 6 μSv·h−1. For the machine learning modeling, Keras framework in a Python environment is used. The algorithm chosen to construct machine learning model is regression with 15,000 number of nodes in each hidden layer. The pulse-shaped signals measured by photomultiplier tubes are saved as discrete digits and each pulse data consists of 1,024 number of them. Measurements are conducted separately to create machine learning data used in training and test processes. Measurement times were different for obtaining training and test data which were 1 minute and 5 seconds, respectively. It is because sufficient number of data are needed in case of training data, while the measurement time of test data implies the actual measuring time. The machine learning model is designated to estimate the source positions using the information about time difference of the pulses which are created simultaneously by the interaction of gamma ray and plastic scintillating fiber sensor. To evaluate whether the double-trained machine learning model shows enhancement in accuracy of source position estimation, the reference model is constructed using training data with one-time learning process. The double-trained machine learning model is designed to construct first model and create a second training data using the training error and predetermined coefficient. The second training data are used to construct a final model. Both reference model and double-trained models constructed with different coefficients are evaluated with test data. The evaluation result shows that the average values calculated for all measured position in each model are different from 7.21 to 1.44 cm. As a result, by constructing the double-trained machine learning model, the final accuracy shows 80% of improvement ratio. Further study will be conducted to evaluate whether the double-trained machine learning model is applicable to other data obtained from measurement of gamma ray sources with different energy and set a methodology to find optimal coefficient.

Concrete is one of the largest wastes, by volume, generated during the decommissioning of nuclear facilities, which significantly influences the projected costs for the disposal of decommissioning wastes. Concrete consists of aggregates and a cement binder. In radioactive concrete, the radioisotopes are mainly associated with the cement component. If the radioactive isotope can be separated from the concrete to below the clearance criteria, the volume of radioactive concrete waste could be reduced effectively. We were studied to separate the radioactive materials from the concrete by using the thermomechanical and chemical treatment processes, sequentially. From the study, separated aggregate could be treated to achieve the clearance level. However, these processes generate a large volume of secondary acidic radioactive wastewater, which might be a critical problem to reduce the volume of radioactive concrete waste. In this research, separating the 137Cs and 90Sr from dissolved concrete wastewater to below the discharge criteria by precipitation method, it would be released to the environment under industrial waste guidelines. The experiments were conducted to using a simulated radioactive wastewater, formed by the dissolution of concrete within HCl, which was spiking the 137Cs and 90Sr, respectively. In addition, we applied the chemical precipitation methods with wastewater, using ferrocyanide for 137Cs and BaSO4 coprecipitation for 90Sr. As a result, targeted radionuclides could be removed to the discharge level (137Cs: 0.05 Bq·ml−1, 90Sr: 0.02 Bq·ml−1) by precipitation method. Therefore, it could reduce the secondary wastewater effectively by precipitation method and enhance the additional volume reduction for radioactive concrete waste.

Since nuclear power plant (NPP) dismantling carries the possibility of radiation exposure from a hazardous environment, it’s important to minimize that by using a remote manipulator et al. However, due to complexity of nuclear facilities, it’s necessary for operators to increase their proficiency by operating in advance in a virtual environment. In this research, we propose a virtual manipulator system using a haptic device for NPP’s reactor vessel internals (RVI) dismantling which can realistically manipulate.

Radioactive carbon, C-14, can be generated by the neutron capture reaction of O-17 during the nuclear power plant operation. Since C-14 is classified as an intermediate level waste radionuclide, it is required that an effective separation process for C-14. C-14 is mainly absorbed on activated carbon in the air cleanup system. Therefore, the main generation source of C-14 during the nuclear power plant decommissioning is spent activated carbon. KAERI has been developing the treatment of spent activated carbon. In this process, C-14 can be desorbed as a gaseous oxide form from the spent activated carbon at high-temperature vacuum conditions. This radioactive carbon dioxide can be captured into alkaline earth metal incorporated glass and can be transformed into carbonate form. However, the carbonate (e.g. CaCO3 and SrCO3) is dispersive. When the radioactive carbonates are disposed into a geological repository, they should be immobilized to remove future uncertainty. This study examined the stabilization/immobilization of the radioactive carbonates by the cement hydration process. Cement wasteform incorporated with calcium carbonate and strontium carbonate was produced under various waste loading (e.g. 20wt%, 40wt%, and 60wt% of CaCO3 and SrCO3, respectively). Then we evaluated mechanical and chemical durability by measuring compressive strength and leachability according to standard test methods specified in the waste acceptance criteria of the Gyeongju low and intermediate level waste repository (WAC-SIL-2022-1). Also, microstructure and thermal characteristics were investigated by SEM-EDS and TGA analysis.

Radioactively contaminated metal components from a nuclear power plant must be decontaminated to reduce the risk of radiation exposure to workers, which can be cleaned using a foam decontamination used to reduce the amount of wastewater significantly. Metal components with a fixed radioactive contamination can be effectively decontaminated using a foam consist of 0.5wt% nonionic surfactant, 0.5 M H2SO4, and 0.2 M Ce(SO4)2. However, strongly acidic wastewater is generated from the decontamination method, which contains a high concentration of the nonionic surfactant and ionic materials with radioactive nuclides. This wastewater must be treated as a stable form. In this study, an integrated process of precipitation and low pressure distillation was evaluated for the treatment of wastewater. It was confirmed that the surfactant and ionic materials were effectively removed from the wastewater through the integrated process.

The decommissioning of Kori unit 1 is just around the corner. Accordingly, it is required to construct a hot cell facility for decommissioning nuclear power plants to analyze the characteristics of intermediate-level waste and low-level waste generated in the decommissioning process. In this study, a Design Base Accident (DBA) scenario of the facility is developed. To identify and characterize potential hazards at the facility, a Preliminary Fact Sheet (PFS) is filled out and consider external events in consideration of the surrounding site environment. The external event screening and evaluation method is based on the external event evaluation method covered in the probabilistic risk assessment. In PFS, only natural and artificial hazards that may have a meaningful impact on the facility are considered as the sources of the accident, and accident prevention and mitigation systems, etc., which exist in each compartment or facility, are described. Based on PFS and external events, potential hazard assessment is systematically performed using each potential hazards, impact and defense function identified using the preliminary hazard analysis (PHA) methodology. The potential hazard analysis methodology applied to this assessment is a qualitative assessment method consistent with the US DOE Hazard Analysis methodology (DOE 1992b; DOE 1994b). After that, the potential mitigation functions that can be used under normal, abnormal and accident conditions are examined, and the contribution of public and workers to safety is evaluated. The results of the PHA are basic data that prioritize potential hazards and can be used to develop potential accident scenarios. Among potential hazards generally considered for non-reactor facilities, only possible accidents during operation of the facilities are selected as potential hazards. The level of potential hazards is obtained by qualitatively examining the frequency and consequence estimates for each hazard or accident scenario developed in PHA. Based on the results of the potential hazards assessment, representative accidents that require further quantitative analysis are screened. Selected accidents are DBA and are the most dangerous and most significant impacts on workers.

The decommissioning of nuclear power plant (NPP) generates large amount of waste. Since the most of the concretes are slightly surface contaminated, the accurate characterization and regionspecific surface decontamination are important for the efficient waste management. After the effective surface decontamination and separation, most of the concrete waste from decommissioning of NPP can be classified as a clearance waste. Various surface characterization and decontamination technologies are suggested. The mechanical technologies are simple and offers direct application. The laser-based technologies offer efficient separation and surface contamination. The high price, however, hesitates the application of the process. The nitro-jet technology, which is based on the evaporation of liquid nitrogen, allows the effective decontamination. However, the high price and uncertainty of large are application hinders the practical application in NPP decommissioning. In this paper, various technologies for characterization, handling, treatment, etc., will be discussed. The advantages and disadvantages of the technologies will be discussed, in terms of practical applications.