In this study, comparative combustion was performed in a 3-ton flue tube boiler for emulsified oil manufactured by using 15% water and approximately 1% carbide aqueous solution as an emulsifier in Bunker-C oil, and the characteristics of exhaust emissions were analyzed. As a result of performing comparative combustion under the same ambient environment and external conditions, the exhaust gas temperature decreased by approximately 3.93% from 183.76℃ for bunker-C to 176.52℃ for EM15, and the oxygen concentration increased by approximately 2.96% from 9.72% to 12.68% . Carbon dioxide decreased by approximately 2.3% from 8.49% for bunker-C to 6.19% for EM15, indicating that EM15 has a greenhouse gas reduction effect. When the standard oxygen concentration of 4% was applied, nitrogen oxides decreased by approximately 43.17% from 130.59 ppm for Bunker-C to 74.21 ppm for EM15, and sulfur oxides decreased by approximately 53.05% , confirming the excellent emission reduction characteristics of emulsified fuel oil. Therefore, it is expected that replacing emulsified fuel oil in boilers using Bunker-C oil will enable response to increasingly strengthened emission regulations.

The IMO’S 72nd MEPC meeting proposed the goal of reducing greenhouse gas emissions by up to 50% by 2050. Thus, various eco-friendly fuels are proposed as alternatives, but there are also various issues that need to be tackled, such as storage stability and supply system issues in a special environment a ship has. Therefore, in this study, the possibility of reducing greenhouse gases was analyzed by applying MGO as an alternative to boilers operated with HFO, a Bunker-C series. As a result, the exhaust gas temperature decreased by about 11.54% from 316.9℃ to 280.3℃, and the amount of oxygen content increased by about 0.38% from 6.27% to 6.65%. It can be seen that carbon monoxide can be reduced by about 45.28% by simply converting fuel from 45.29 ppm to 24.78 ppm, and carbon dioxide, which is a typical greenhouse gas, can be reduced by about 0.49% from HFO by 11.08% to MGO by 10.59%. This means that some greenhouse gas reduction is possible only by shifting between ship fuels that satisfy ISO-8217, but since there are limitations to achieving strong carbon neutrality proposed by IMO, it will be necessary to actively utilize the use of various alternative fuels in the future.

In this study, we compared and analyzed the influence of the non-face-to-face contact restriction policy due to the COVID-19 pandemic (COVID-19) on the fishing output of two 70-ton offshore trap fishing vessels in Gyeongsangnam-do. Compared to the COVID-19 period, the fishing output increased by about 20% after the end of regulations, but there was almost no significant change in monthly sales. As a result of statistical processing, the unit price of consignment sales per kg showed a significant difference at the p<0.05 level, and there was no difference in variables in the output and monthly sales. It was determined that government support was needed to stabilize the supply of marine products and market prices in preparation for the future post-coronavirus.

김정은은 집권 초기 사회주의 강성국가 건설을 국가목표로 제시하였으 며 핵개발과 경제발전을 주요 정책으로 추진하였다. 김정은 시대 북한이 추진한 주요 정책의 특징은 당에 의한 정책목표 결정, 정책추진을 위한 계획수립, 법제정을 통한 정책추진의 당위성 확보, 기구편성을 통한 정책 추진이었다. 김정은은 우주강국 건설을 새로운 목표로 제시하고 있다. 이 연구에서는 북한의 우주개발정책을 김정은 시대 주요 정책추진 특징을 가지고 분석하였고, 당 제9차 대회가 제시할 우주개발의 목표와 향후 정 책추진과제들을 살펴보았다. 그리고 북한의 우주개발이 가져올 수 있는 위협을 알아보고 우리의 대응방향을 제시하였다. 현재의 북한의 우주기 술은 우리에게 직접적인 위협이 되지 않을 수도 있다. 그러나 북한이 우 주개발을 목표로 정책을 추진하는 만큼 이에 대한 우리의 대비는 지금부 터 필요하다 하겠다.

이 연구에서는 김정은 시대 북한의 핵 관련 법에 나타난 핵전략과 핵 태세를 분석하였다. 북한은 미국의 대북 적대시 정책에 대한 대응으로 핵을 개발하였다고 주장하였으나, 김정은 시대 북한은 핵 관련 법을 제 정하고 핵을 무기화하였으며 핵능력을 고도화하였으며 당 제8차 대회 이 후에는 전술핵능력까지 구비하였다. 연구를 통해 북한이 핵을 군사적으 로 사용할 능력을 구비하고 고도화하면서 핵전략과 핵태세가 공세적으로 변화하였음을 확인할 수 있었다. 북한의 핵능력이 고도화되면서 핵전략 은 선언적 수준의 최소억지전략에서 대남 제한억지전략과 대미 최소억지 전략으로 발전하였고, 핵태세 또한 현재는 가장 공세적인 비대칭확장태 세 유형을 보여주고 있다. 북한의 핵·미사일 능력 고도화는 계속될 것이 다. 북한의 핵능력증가에 따른 대응 방안 마련이 제한되는 우리로서는 궁극적으로 북한의 핵 위협이 증가하지 않도록 하는 것이 중요하다.

This study intends to analyze physical and chemical changes using Thermo-Gravimetric Analysis （TGA） of MGO-bioethanol mixed fuel oil. We will analyze the thermal stability and state changes of MGO-Bioethanol mixed fuel oil and conduct and utilize various basic experiments on its applicability as ship fuel oil in the future and eco-friendly alternative fuels. The physical and chemical conditions set through this experiment were set through non-isothermal heating at about 20°C to 933°C, and the heating rate was 100°C/min, the measurement time was 10 minutes, and the amount of samples in each mixed fuel oil was about 18mg-24mg. In the range of pyrolysis temperatures from 235.241°C to 253.320°C, the weight of BE0 was 30.992%, BE10 was 36.199.%, BE20 was 35.879%, and BE30 was 35.725%, indicating that the pyrolysis temperature and weight tended to increase as the bioethanol content increased.

In this study, hybrid devices were developed to simultaneously remove odor and particulate matter (PM) emitted during meat grilling, and their performance was evaluated. A ceramic filter system and surfactant microbubble plasma system were used to reduce particulate matter. For odor reduction, an electro-oxidation system, an ozone-active catalytic oxidation system, and a multi-adsorption filter system were used. By combining the above particulate matter reduction and odor reduction devices, the reduction efficiency of odor and particulate matter generated during meat grilling was analyzed. As a result, most of the six combined device conditions showed a reduction efficiency of more than 90% for particulate matter. The combined odor also showed a high reduction efficiency of less than 200 times the emission concentration standard. This study also evaluated 22 types of odorous substances, of which ammonia (NH3) and hydrogen sulfide (H2S) showed removal efficiencies of more than 99%. Therefore, it is expected that the combination of these technologies can be used and applied directly to the sites where meat grilling restaurants are located to effectively contribute to the simultaneous reduction of particulate matter and odor.

Biodiesel is a traditional energy field that can replace low-quality marine fuels for ships and various studies have been conducted. Since the 2000s, Korea has introduced a mandatory supply system of biodiesel for domestic vehicle diesel, gradually raising the blending ratio from 0.5% to 3.5%, and is expected to raise the mandatory blending ratio to about 8.0% by 2030. Therefore, in this study attempted to blend high-quality samples that meet the biodiesel quality standards manufactured by domestic companies with MGO in ratios ranging from 0 to 60%. We utilized a 1-ton combustion chamber to compare and analyze the exhaust gas emissions characteristics. As a result, in the BD60 condition, which represents the maximum range in this study, the O2 increased by approximately 1.5%p, and CO2 tended to decrease by 1.1%p. NOx decreased by approximately 18.2%p from 34.1 ppm to 27.9 ppm. In the case of SOx, a very low concentration of 0.08 ppm was detected under the BD0 condition, and it was undetectable under all other conditions containing biodiesel. This suggests that MGO itself has excellent low-sulfur oil quality and can implement zero SOx through biodiesel mixing. Furthermore the combustion efficiency decreased by approximately 1.91%, from 72% to 70.2%, and the exhaust gas temperature also decreased by about 4.5%p. However despite the lower calorific value of biodiesel compared to MGO, it demonstrated relatively close thermal output per unit content. This indicates sufficient potential for biodiesel to serve as a viable alternative fuel for ships in the future.

The purpose of this study intends to development of a lap scale 1-ton standard combustion chamber. The manufactured standard combustion chamber analyzes pilot combustion tests and emission standard data of MGO fuel oil. The actual capacity of the standard combustion chamber is about 900L, total weight of 265kg. As a result of the pilot combustion test, the O2 was about 8.01% and the CO2 was about 9.34%. In the case of NOx, it was about 33.50 ppm, and SOx (SO2) was about 0.76ppm. The combustion efficiency was about 72.41%, the exhaust gas temperature was 366.7℃, and the combustion chamber internal temperature was about 448.0℃.

This study intends to use the possibility of an eco-friendly alternative fuel to be applied to ships as a sample manufacturing method for ship MGO and bioethanol mixed fuel oil as basic evidence. The components of the manufactured mixed fuel oil were analyzed using the ISO-8217 standard testing method. As a result of analysis showed that in the lower calorific value decreased to 43030J/g at BE0 fuel and 37010J/g at BE30 fuel. The high calorific value decreased to 46.065MJ/kg at BE0 fuel and 39.460MJ/kg at BE30 fuel. The density decreased to 840.8kg/m3 at BE0 fuel and 837.0kg/m3 at BE30 fuel. In the case of flash point it was 67.5℃ when BE0, and decreased to less than 40.0℃ when BE10 to BE30. Finally the Kinematic Viscosity was 3.011mm2/s at BE0 and decreased to 2.502mm2/s at BE30.

Since ships are exposed to noise and vibration for a long time in seas isolated from land, the stress of workers is high, requiring studies on the improvement of the problem. In addition, the health of crew members on fishing vessels, unlike commercial ships, carrying out fishing activities is closely related to fishing performance. However, considering that most of IMO's guidelines apply to merchant ships, provisions should be made for vibration in accommodation areas of fishing vessels. Accordingly, this study, applying the revised ISO 20283-5:2016 standard and through experiment, investigated the vibration characteristics of the accommodation area for each operating conditions of a 1000-ton trawler fishing vessel. Within the scope of the study and the full-ahead mode, the vibration was highest in the engine control room (4.17mm/s) while the acceptable standard was satisfied sufficiently in all conditions. Application of the merchant vessel vibration standard to fishing vessel is expected to improve the working environment of fishing vessel crew members.

We conducted research on the removal performance of various odor substances using a deodorizing agent, hypochlorite ion (OCl-), in odor emission sites where various odor-causing substances occur simultaneously. In experiments treating odor gases containing mixtures of aldehydes (acetaldehyde, n-butyl aldehyde, iso-valeraldehyde, propionaldehyde), sulfur compounds (hydrogen sulfide, methyl mercaptan, and dimethyl sulfide), and nitrogen compounds (ammonia and trimethyl amine), it was demonstrated that the introduced odor substances could be simultaneously removed when electrolyzed water was used. The overall removal efficiency was found to be significantly higher than when water alone was used. Particularly, it showed simultaneous effectiveness against acidic, neutral, and alkaline odor substances such as ammonia and hydrogen sulfide. Considering the positive aspects with regard to chemical safety, the use of salt instead of chemicals, and the continuous regeneration of the oxidizing agent, this environmentally friendly deodorization technology is expected to contribute to securing excellent odor removal capabilities and wide-ranging deodorization applications.

Recently, the International Maritime Organization is strengthening regulations for ships operating in polar regions. Hence, insulated multi-core tubes as components for vessels operating in extreme cold need to be investigated in various aspects. Furthermore, the demand for research on electric propulsion vessels is also increasingly growing. Thus, to utilize a 4-core insulated multi-core tube with glass wool as insulation, which was previously developed for ships operating in polar regions, as a water-cooled electrical cable, this study conducted an experiment on the temperature change when water at normal temperature 25℃ was supplied as a coolant under the overcurrent varied from 10A to 25A. As a result, the temperature increase of the core in 10A condition was 3.3℃, but it increased to 13.05℃ in the 25A condition. This showed that a temperature difference of approximately 9.75℃ occurred according to the overcurrent load. However, the coolant inlet and outlet temperatures were relatively uniform around 1℃ in all conditions. This suggests that increasing the residence time by proper control of the coolant flow in the future could achieve a higher cooling effect.

In this study, in order to confirm the machining characteristics of AISI 1020 CD-Bar, cutting was performed after strength measurement, and surface roughness analysis was performed according to cutting conditions. Tensile strength was reduced by about 27.7% compared to AISI 1045 material, and Rockwell hardness HRC was reduced by 46.7%. The surface roughness measurement after cutting was divided into roughing, semi-finishing and finishing turning. In particular, in finishing machining, the best surface roughness was confirmed when the cutting speed was 150m/min and the depth of cut was 0.6mm based on the feed rate of 0.05mm/rev.

The fuel oil used for ships has the viscosity higher than the fuel used for general vehicles and contain impurities, so it’s exhaust gas results in the environment pollution. There have been studies actively conducted to examine alternative fuels for improving the quality of the marine fuel oil. It is, however, necessary to test the quality of fuel for mega ships, by conducting the simulation test using reduced-size models, before the demonstration step, because it takes too much cost and time to directly perform the demonstration of alternative fuels. This study, therefore, developed a 30-liter small-size boiler similar to the ship system and performed an initial fuel test by applying MGO to it. The findings show that the amount of nitrogen oxide to which 4% of the standard oxide level was applied was about 24.69ppm, when the oxide level was 10.02%, with the CO2 of 8.02%, the exhaust gas temperature of 291.15℃ and the combustion efficiency of about 74.53%, indicating that it will be necessary to conduct various studies through the ratio control in the future.

Environmental noise occurring on ships has various negative impacts on sailors’ health conditions such as hearing loss, sleep disturbance, psychological stress, etc., so regulations on them are required, but the ship noise regulations are usually applied to only large merchant ships. Although regulations on fishing boats with strong fishing and work intensity are determined to be necessary, there has been little relevant research. This study, therefore, attempted to measure the environmental noise of coastal composite fishing vessels less than two tones and provide the results of basic research on the noise regulations for fishing vessels. It measured them by setting the measurement zones as after side, midship and fore side, and based on the criterion of IMO MSC 337(91). The findings showed that the noise of them often exceeded 75dB(A), the criterion of the open deck noise in the zones in which the load of main engines was increased. In particular, the noise of the stern was as high as 92.2dB(A) during the full ahead. Hence, hearing loss may be caused by such a noise, so a variety of regulations on it are determined to be necessary.

Korea is a country where the population is concentrated in metropolitan areas that have undergone rapid industrial development. As of 2020, more than 43% of the total population lives in large cities, and about 18.5% of the total population lives in Seoul. A basic human need living in such a metropolis is a pleasant environment. In this study, complex odors and designated odors were evaluated at the boundary areas and at the outlets for 15 public environmental facilities selected from among odor sources in Seoul. As a result of measuring the complex odor intensity was 3 ~ 6 times at the boundary areas and 100 ~ 4,481 times at the outlets. In food waste treatment facilities, incineration facilities, and waste transfer station facilities, the compound making the largest contribution to odor is acetaldehyde, which was recorded at 46%, 25%, and 32% respectively. At a sewage treatment facility and agro-fisheries wholesale market, hydrogen sulfide was the largest contributing compound at 71% and 29% respectively.

Complaints about foul odors are emerging as an issue, and the number of complaints is steadily increasing every year. Biofiltration is known to remove harmful or odorous substances from the atmosphere by using microorganisms, and full-scale biofilters are being installed and operated in various environmental and industrial facilities. In this study, the current status and actual odor removal efficiency of full-scale biofilters installed in publicly owned treatment facilities such as sewage, manure, and livestock manure treatment plants were investigated. In addition, the effects of design and operating factors on their efficiency were also examined. As a result, it was found that odor prevention facilities with less than 30% odor removal efficiency based on complex odors accounted for 40%-50% of the biofilters investigated. In investigating the appropriate level of operating factors on odor removal efficiency, it was found that compliance with the recommended values p lays a significant role in improving odor removal efficiency. In the canonical correlation analysis for the on-site biofilter operation and design data, residence time and humidity were found to be the most critical factors. The on-site biofilter operation and design data were analyzed through canonical correlation analysis, and the residence time and humidity maintenance were found to be the most important factors in the design and operations of the biofilter. Based on these results, it is necessary to improve the odor removal efficiency of on-site biofilters by reviewing the effectiveness of the operation factors, improving devices, and adjusting operating methods.