In modern society, buildings are becoming more complex, and the population is becoming more densely populated. Such large buildings require a variety of evacuation measures, as there is a high possibility of large-scale human casualties due to increased evacuation distance and evacuation time in the event of a fire. Strobe light and exit sign light are used as important evacuation equipment to provide early warning and evacuation directions. In this thesis, we conducted a fire simulation assuming that a fire occurrence point notification function and a strobe light function were added to equipment such as visual alarms and evacuation guidance, and compared and analyzed the difference in evacuation completion time with existing equipment. The scenarios for the simulation were divided into “general fire situations” and “fire location and evacuation exit guidance situation” and the differences in evacuation completion time in the event of a fire were compared and analyzed for each floor from the 1st floor to the 3rd floor. The maximum travel distance to complete evacuation in the case of a fire on the first floor decreased by 80.6 m and the evacuation completion time decreased by 329.4 seconds, and the maximum travel distance to complete evacuation in the case of a second-floor fire decreased by 28.5 m and the evacuation completion time by 438.8 seconds. During the fire on the third floor, the maximum distance decreased until evacuation was completed to 3.4 m, and the evacuation completion time was reduced by 355.6 seconds. It is expected that if the congestion level of evacuation routes is reduced by utilizing the congestion level of evacuation exits when fire alarm systems and evacuation equipment are activated, the evacuation completion time will be further shortened and evacuations will be carried out quickly and safely.

Kori Unit 1 nuclear power plant is a pressurized water reactor type with an output of 587 Mwe, which was permanently shut down on June 18, 2017. Currently, the final decommissioning plan (FDP) has been submitted and review is in progress. Once the FDP is approved, it is expected that dismantling will begin with the secondary system, and dismantling work on the primary system of Kori Unit 1 will begin after the spent nuclear fuel is taken out. It is expected that the space where the secondary system has been dismantled can be used as a temporary storage place, and the entire dismantling schedule is expected to proceed without delay. The main equipment of the secondary system is large and heavy. The rotating parts is connected to a single axis with a length of about 40 meters, and is complexly installed over three floors, making accessibility very difficult. A large pipe several kilometers long that supplies various fluids to the secondary system is installed hanging from the ceiling using a hanger between the main devices, and the outer diameter of the pipe is wrapped with insulation material to keep warm. In nuclear secondary system decommissioning, it is very important to check for radiation contamination, establish and implement countermeasures, and predict and manage safety and environmental risks that may occur when cutting and dismantling large heavy objects. So we plan to evaluate the radiation contamination characteristics of the secondary system using ISOCS (In- Situ Object Counting System) to check for possible radioactive contamination. According to the characteristics results, decommissioning plans and methods for safe dismantling by workers were studied. In addition, we conducted research on how to safely dismantle the secondary system in terms of industrial safety, such as asbestos, cutting and handling of heavy materials and so on. This study proposes a safe decommissioning method for various risks that may occur when dismantling the secondary system of Kori Unit 1 nuclear power plant.

This study aimed to provide better understanding of the bedrock aquifer bacterial communities and their functions in deep geological repository (DGR) environment. Two study sites of uranium deposits in the Ogcheon Metamorphic Belt were selected: Boeun and Guemsan. From two study sites, six groundwater samples were obtained with different boreholes and depths: OB1 (Boeun, 25 m), OB3 (Boeun, 80 m), GS1 (Guemsan, 25 m), GS2 (Guemsan, 85-90 m), GS3-I (Guemsan, 32- 38 m), GS3-II (Guemsan, 70-74 m). The physicochemical properties of groundwater were analyzed by multi-parameter sensors, ion chromatography (IC), and inductively coupled plasma optical emission spectroscopy (ICP-OES). Illumina Miseq sequencing was performed to investigate bacterial community in six groundwater samples. In addition, the number of sulfate-reducing bacteria (SRB) was quantified by a quantitative PCR (qPCR). Bacterial community composition varied in response to boreholes and depths. A total of 14 different phyla and 36 classes were detected from six groundwater samples. Overall, Proteobacteria, Actinomycetota, and Bacteroidota were dominant in the phylum level. SRB and iron-reducing bacteria (IRB) were detected in all groundwater samples even though organic carbon sources were not abundant (0.7-3.3 mg-total organic carbon/L). This result shows a potential to immobilize uranium in DGR environment. In particular, SRB, Desulfosporosinus fructosivorans and Humidesulfovibrio mexicanus were mainly detected in GS1 and GS2 groundwater samples, which attributed to higher dissimilatory sulfite reductase functional gene copy number in GS1 and GS2 groundwater samples. Statistical analysis was performed to understand the correlation between environmental factors and core bacterial species. Dissolved oxygen (DO), Fe, and Mn concentrations were positively correlated with Curvibacter fontanus while Undibacterium rivi had a negative correlation with pH. These results indicate that bacterial community could be changed in response to environmental variation. Further study with a greater number of samples is necessary to obtain statistically reliable and meaningful results for a safe DGR system.

LNG propulsion ships are actively being built as an eco-friendly fuel for ships, and ships with C-type LNG tanks are being widely built. In order to analyze the risk of LNG venting from operating ships and test-run ships, the flow characteristics according to operating conditions were reviewed using ANSYS FLUENT, a computational fluid dynamics (CFD) software. As a result of the study, it was confirmed that the distribution area exceeding the lower explosion limit of natural gas and the area where the natural gas temperature rose to 17 ° C had similarities. In addition, it was confirmed that the change in the horizontal direction was greater than the change in the vertical direction when the natural gas distribution range was changed. Since the valve opening has a greater effect than the tank pressure, if natural gas must be vented to the atmosphere inevitably, the risk can be reduced by operating the valve opening at 50% or less.

This study focuses on critical brands, design, and material functionality in contemporary golf, workwear, and outdoor clothing. The research employs a detailed case study approach, analyzing product characteristics to gauge current industry trends and predict future trajectories in functional clothing. The results reveal an industry-wide adoption of advanced materials and ergonomic design features to enhance performance, comfort, safety, sustainability and durability. A noticeable shift towards sustainability, versatility, and adaptability is also identified as a growing consumer expectation. In conclusion, the study offers an all-encompassing view of the functional apparel market, potential future trends, and concrete applications for enhancing the Korean civil defense uniform.

The aim of this study was to determine the contamination of mycotoxins and the concentration of preservatives and antioxidants in commercial pet food. 106 pet foods were purchased from online in Korea. Mycotoxin analysis were performed using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) and preservatives and antioxidants were analyzed by high performance liquid chromatography (HPLC). The contamination of the mycotoxins in all samples was proved to comply with the Korea legislation with regards to animal feed, the analyses revealed presence of aflatoxins, ochratoxin A, zearalenone and fumonisins, with values below 1.6 ㎍/㎏, 12.1 ㎍/㎏, 478.5 ㎍/㎏ and 1873.5 ㎍/㎏, respectively. Furthermore, the simultaneous presences of different mycotoxins were observed in most of positive samples. The levels of dehydroacetic acid (DHA), sorbic acid (SA) and benzoic acid (BA) were, respectively, with values below 0.24 g/㎏, 4.82 g/㎏ and 6.35 g/㎏. The concentrations of butylated hydroxy anisole (BHA) and butylated hydroxy toluene (BHT) were demonstrated to be acceptable, with values below 0.04 g/㎏, and 0.02 g/㎏. This indicated the need for further investigation into the potential risk deriving from chronic exposure to low doses of mycotoxins. Additionally, a co-contamination of mycotoxins which interact in synergic manner are more concern. As DHA that not accepted was detected and very high levels of SA were identified in samples, an upper limit for preservatives in pet foods should be established in pet foods. BHA and BHT were detected within the recommended levels for antioxidant content, so these are considered as safe.

이􀀁 논문에서는􀀁 회귀분석,􀀁 VAR,􀀁 Lasso,􀀁 XGBoost􀀁 등􀀁 4가지􀀁 통계􀀁 기법을􀀁 이용하여􀀁 비트 코인과􀀁 금융시장과의􀀁 상호연관성의􀀁 정도를􀀁 밝혀􀀁 비트코인이􀀁 더􀀁 이상􀀁 안전자산이􀀁 아님을􀀁 보였다.􀀁 회귀분석에서는􀀁 비트코인의􀀁 24시간􀀁 시간별􀀁 데이터를􀀁 이용하여􀀁 미국주식시장􀀁 개장 시간대와􀀁 휴장시간대를􀀁 비교하여􀀁 비트코인의􀀁 거래량과􀀁 가격의􀀁 변동성이􀀁 통계적으로􀀁 유의 미하게􀀁 증가하는지를􀀁 분석한􀀁 결과,􀀁 미국증시􀀁 개장시간대(09:30-16:00)에􀀁 그􀀁 외의􀀁 시간대 에􀀁 비해􀀁 비트코인의􀀁 거래량은􀀁 22%,􀀁 가격변동성은􀀁 8.3%􀀁 증가하는􀀁 것으로􀀁 나타났다.􀀁 또 한􀀁 비트코인의􀀁 주별􀀁 자료를􀀁 이용하여􀀁 다양한􀀁 주식시장􀀁 지수들이􀀁 시차를􀀁 두고􀀁 비트코인􀀁 수 익률(가격증가율)과􀀁 변동성에􀀁 어떤􀀁 영향을􀀁 미치는지를􀀁 VAR􀀁 분석한􀀁 결과,􀀁 연방기준금리가􀀁 가장􀀁 직접적으로􀀁 영향을􀀁 미치는􀀁 것으로􀀁 나타났다.􀀁 한편􀀁 Lasso를􀀁 이용한􀀁 비트코인과􀀁 주요􀀁 시장의􀀁 지수들과의􀀁 상관관계의􀀁 방향성􀀁 분석에서는􀀁 비트코인의􀀁 수익률과􀀁 변동성이􀀁 금융시 장􀀁 지수들과􀀁 정확히􀀁 같은􀀁 방향으로􀀁 움직이는􀀁 것으로􀀁 나타났다.􀀁 마지막으로􀀁 XGBoost를􀀁 이 용한􀀁 분석에서는􀀁 비트코인􀀁 수익률과􀀁 변동성을􀀁 예측하는데􀀁 가장􀀁 강력한􀀁 예측변수들은􀀁 미국􀀁 주식시장의􀀁 S&P􀀁 500􀀁 지수,􀀁 나스닥􀀁 지수,􀀁 다우존스􀀁 변동성지수인􀀁 것으로􀀁 나타났다.􀀁 다양 한􀀁 계량분석􀀁 결과,􀀁 비트코인은􀀁 미국􀀁 금리와􀀁 미국􀀁 주가􀀁 움직임에􀀁 매우􀀁 민감하게􀀁 반응하고􀀁 정확히􀀁 같은􀀁 방향으로􀀁 움직여􀀁 더􀀁 이상􀀁 안전자산이􀀁 아님을􀀁 밝혔다.􀀁

한 척의 선박을 건조하기 위해서는 다양한 크기의 블록(block)들을 이동 및 탑재해야 한다. 이러한 과정에서 블록의 체결 방법 및 각 조선소 설비 특성에 맞는 다양한 기능에 부합하는 러그를 사용하고 있다. 블록 구조의 중량 및 형태에 따라서 러그의 크기와 형상이 다양하며, 샤클(shackle)이 체결되는 홀 주변에 부족한 강성을 보완하기 위하여 덧판(doubling pad)을 용접하여 구조를 보강한다. 리프팅 (lifting) 조건별 러그의 설계를 하는 방법은 보 이론(beam theory)에 의한 수계산 방법과 유한요소해석 모델링을 이용한 구조해석을 수행하고 있다. 해석적 방법의 경우, 요소의 종류와 모델링 방법에 따라서 결과 차이가 발생하여 표준화된 평가법의 정립이 필요한 상황이다. 이러한 모호한 방법론 적용 시 블록의 이동 및 반전(turn-over) 과정 중에서 심각한 안전 문제를 유발할 가능성이 있다. 본 연구에서는 러그의 실제 탑재공정에 따른 구조 응답을 평가할 수 있는 모델링 조건, 평가법을 확정하고자 다양한 변수의 영향을 수치 구조해석을 통하여 비교 및 분석하였다. 러그 홀(hole) 주변 덧판부와 용접 비드(bead)를 표현한 모델링 기법이 가장 실제적인 거동 결과를 주고 있다. 실제 러그와 동일 한 조건(용접부 비드만 주재료와 연결)의 모델링에 등가하중을 적용한 결과는 MPC 하중 적용 결과보다 낮은 최종강도를 나타낸다. 더불어 해석 시간 단축을 위해서 2차원 쉘(shell) 요소를 적용한 경우, 덧판 두께를 85% 수준으로 감소시켜서 안전사용하중을 예측할 수 있음을 확 인하였다. 논문에서 검토한 다양한 변수의 영향들 결과는 러그 설계 및 안전사용하중 예측에 근거 자료로 활용될 것으로 기대된다.

Laser cutting has many advantages, including high-speed cutting potential, no reaction forces, narrow kerf widths, ease of remote control, and more. This makes it the next generation cutting technology for nuclear decommissioning. For this reason, various groups in countries with nuclear power plants have been working on applying laser cutting to nuclear decommissioning. Our group has also been developing in-air and underwater laser cutting technologies. Previous research has focused on efficiently cutting thicker steels. To accomplish this, a cutting head with a long focusing element with a focal length of 600 mm was utilized. A long focusing head is advantageous for cutting thick objects at high speeds because it can maintain a high power density over a long distance. However, with such a long focused beam, the residual laser power that remains after passing through the target object can cut or damage other unwanted objects located behind the target. Utilizing a short focused element can solve this problem, but if the focal length is too short, the cutting capability will be reduced. In this work, we developed and applied a cutting head that utilizes a focused element with a short focal length of 300 mm. Cutting tests with this head allowed us to cut 10-60 mm thick stainless steel plates at a laser power of 6 kW. We also obtained the maximum cutting speed and kerf width for each thickness while increasing the laser power by 1 kW from 1 to 6 kW. The results obtained in this work are expected to be utilized for safe cutting in future nuclear decommissioning applications.

The need for an intelligent information-based ship accident prevention and control system for various marine accidents is very clearly emerging. As it is a variety of marine accidents, the causes are diverse. Therefore, it can be said that it is very important to prevent these marine accidents and their causes in advance. Therefore, a study was conducted on an intelligent information-based ship safety management decision support system that provides information necessary for decision-making at sea and land through an integrated management device for ships that informs safety-related risks in real-time ship operation. In the future, we intend to pursue the development of a system that can aim for safer and more economical ship operation by linking it to navigation instruments through the evaluation and analysis of AI, IoT, and big data.

This study analyzes the importance and implementation of countermeasures to reduce safety accidents that may occur during fishing in coastal gillnet fishing. Safety accidents that may occur in coastal gillnet fishing were classified into 56 measurement items in six areas: slips and trips, contact with machinery, falls, struck by object, musculoskeletal symptoms, and electrical shock. 35 fishermen belonging to coastal gillnet associations in Tongyeong and Namhae were selected as samples, and the importance and implementation of the proposed measurement items were investigated in the field. In addition, the results were evaluated visually by IPA analysis. As a result of the analysis, the importance of struck by object was the highest, and the implementation of slips and trips was the highest. On the other hand, prevention of musculoskeletal damage was found to be the lowest in both importance and implementation. The area with the most significant difference in importance and implementation by the classified area for measurement items was struck by object, and the area with the minor difference was slips and trips. Among the measurement items, the importance is highly recognized, but there are items with low implementation. To improve their level of implementation, countermeasures such as continuous education, economic support, and structural change of fishing boats should be prepared; moreover, policy support activities for implementation should be carried out.

전 세계적으로 해상을 마주하고 있는 여러 국가들은 기존의 전력 생산방식의 단점을 극복하고 해상풍력 개발을 통한 친환경에 너지자원을 활용하고 있다. 해상은 넓은 해역에 대규모 풍력단지를 개발할 수 있는 장점이 있으나 해양구조물의 설치로 인해 선박의 안 전운항이 위협받고 있다. 이에 따라, 선박 통항로와 해상풍력단지 간 상호 미치는 영향에 대해 분석하여 선박이 안전하게 운항할 수 있도 록 PIANC에서는 표준 Guideline을 제시하였다. 그럼에도 불구하고, 표준 Guideline은 모든상황에서 동일한 이격거리를 산정하였다. 따라서 본 연구에서는 선회성능, 조우상태, 환경외력, 해상밀집도, 해상풍력발전기, 항로형태 등을 요소로 반영한 선박 통항로와 해상풍력단지 간 최적의 이격거리 산정 모델을 개발하였다. 개발된 모델 검증을 위한 시뮬레이션 결과, 운항 준비상태에 따른 입지 특성별 선회성능 크기 는 산정 모델에서 제시한 크기와 유사하였다.