In modern society, the delivery service market has grown explosively due to rapid changes in social structure and the recent COVID-19 pandemic. Therefore, various problems such as injury to workers and an increase in human accidents are occurring due to the loading and unloading of parcels. In order to solve this problem, domestic company n is developing a “robot-based cargo loading and unloading system”. In developing a new technology system, quantitative reliability targets should be set for efficient operation and development. In this paper, reliability analysis was conducted through field data for the pneumatic gripper of the “robot-based cargo loading system”. The reliability of the failure data was analyzed to estimate the distribution parameters and MTTF. Random data was derived for the probability of occurrence of a failure with the estimated value. By repeating the simulation to predict the number and year of failures according to the estimated parameters of the probability distribution, it was proposed as a method that reflects realistic probabilities rather than calculating with simple arithmetic using the average MTTF previously used in the field.

With the restriction of foreigners’ entry into Korea due to the COVID-19 pandemic, the fishery industry faced significant challenges in supplying migrant workers. In response to this, there is growing interest in methods that could facilitate the stable employment of migrant workers. This paper investigates whether the current system used for the employment of migrant workers in the fishery industry, which is highly dependent on them, adequately performs its function of providing a stable and skilled workforce amid the intensified labor shortage resulting from decreasing numbers of households with employment in the fishery and the aging Korean fishermen. To this end, past studies and government documents pertaining to the current system were analyzed, and a survey targeting the owners of offshore fishing boats that employ migrant workers was conducted. A total of 147 owners of fishing boats responded to the survey, and the data of 499 migrant workers employed by them were used for the analysis. The analysis indicated that the migrant fishermen had difficulty in acquiring minimum scores for the change of visa status according to the criteria for the Skilled Worker Points System. Furthermore, distinct differences were found between the characteristics and working conditions of migrant workers employed through the Employment Permit System (EPS) and the Foreign Seamen System. Based on this result, this paper suggests the reorganization of the skilled migrant worker system in the fishery industry and the expansion of the regional specialized visa pilot project.

PURPOSES : Recently, increasing number of local governments are introducing on-demand public transportation service in real time to improve the management efficiency of public transportation. In preparation for the autonomous driving era, the “autonomous public transportation mobility on-demand service in real time” is being developed in the public transportation sector to introduce on-demand public transportation. For this service to become the public transportation of the future, it must receive publicity. Therefore, in this study, indicators were selected to evaluate the publicity of the autonomous public transportation mobility on-demand service in real time, and a survey was conducted among the general public to examine the validity of the indicators. METHODS : To secure the publicity of on-demand public transportation in real time, the goal of the service was first set. Second, the keywords of the service were analyzed to define the publicity requirements of this service. Based on the analyzed keywords and definition of publicity, service indicator types were classified, and the indicators were defined by type. A user satisfaction survey was conducted on the final selected indicators to improve the degree of completion of indicator development. The user survey was conducted by presenting selected publicity indicators to respondents responding on a five-point scale to determine whether each indicator could satisfactorily evaluate publicity. RESULTS : When examining various previous research cases and the contents required for autonomous public transportation mobility on-demand service in real time, the required items of publicity indicators were found to be “safety” in terms of “autonomous driving” and “convenience” in terms of “demand response.” Publicity indicators were developed according to these three items. Thirty-one indicators were developed, and a satisfaction survey was conducted on the general public for each indicator. In the survey, most of the indicators scored 3.5 points or higher, indicating that the indicators were generally well defined. Users gave the highest score to “fairness” among the three items, and “reasonable fairness” was found to be a necessary item as a publicity indicator. CONCLUSIONS : In this study, evaluation indicators were selected to secure the publicity of autonomous public transportation mobility on-demand service in real time, and a satisfaction survey was conducted for each indicator. Most of the indicators showed a score of 3.5 or higher, indicating that they were generally well defined. However, this study has a limitation in that it surveys the general population. In future, experts should be included in the survey to increase the degree of completeness of the public indicators.

PURPOSES : In this study, high-viscosity grout for increasing ground stiffness is developed using industrial byproducts. METHODS : Based on literature review, the viscosity and viscosity expression time of domestic and foreign anti-washout admixture underwater were evaluated. In addition, grout was prepared by mixing 5% to 40% of fly ash (FA) in a standard mixture. Flow, setting time, and compressive strength tests were conducted to evaluate the quality of the grout. RESULTS : Experimental results show that the viscosity required is 35,000 to 40,000 cps, whereas the viscosity expression time required exceeds 300 min. As the amount of FA used for grouting increases, the physical and mechanical performances deteriorate. The strength of a test specimen manufactured underwater is lower than that of a test specimen manufactured under air, and the decrease on day 28 is lower than that on day 3. The FA applied to the grout should be less than 20%. CONCLUSIONS : Although industrial byproducts, which exhibit high viscosity, offer excellent mechanical performance and are thus suitable as a solidifying agent for strengthening grout, their application in the field must be evaluated.

Recently, considerable attention has been given to nickel-based superalloys used in additive manufacturing. However, additive manufacturing is limited by a slow build rate in obtaining optimal densities. In this study, optimal volumetric energy density (VED) was calculated using optimal process parameters of IN718 provided by additive manufacturing of laser powder-bed fusion. The laser power and scan speed were controlled using the same ratio to maintain the optimal VED and achieve a fast build rate. Cube samples were manufactured using seven process parameters, including an optimal process parameter. Analysis was conducted based on changes in density and melt-pool morphology. At a low laser power and scan speed, the energy applied to the powder bed was proportional to and not . At a high laser power and scan speed, a curved track was formed due to Plateau-Rayleigh instability. However, a wide melt-pool shape and continuous track were formed, which did not significantly affect the density. We were able to verify the validity of the VED formula and succeeded in achieving a 75% higher build rate than that of the optimal parameter, with a slight decrease in density and hardness.

PURPOSES : Roller-compacted concrete pavement (RCCP) is a superstiff-consistency concrete pavement that exhibits excellent strength development owing to a hydration reaction and interlocking aggregates owing to the roller compaction. A zero-slump concrete mixture is generally used. Hence, it is important to control the consistency of the RCCP mixture to prevent the deterioration of the construction quality (such as material separation during paving). The workability of the RCCP is characterized by its consistency and controlled by the Vebe time, whereas a conventional concrete pavement is controlled based on the slump test. The consistency of the RCCP changes over time after concrete mixing owing to delivery, construction time delays, etc. Thus, it is necessary to use the optimum Vebe time to achieve the best construction quality. Therefore, this study aims to develop a Vebe time prediction model for efficiently controlling the consistency of RCCPs according to random time variations. METHODS : A Vebe time prediction model was developed using a multiple linear regression analysis. A dataset of 131 samples was used to develop the model. The collected data consisted of variables with large potential effects on the consistency of the RCCP, such as the water-cement ratio (W/C), sand/aggregate ratio (S/a), water content (ω), water content per unit volume (W), cement (C), fine aggregate (S), coarse aggregate (G), water reducing admixtrue (PNS), air-entraining admixture (AE), delay time (T), air temperature (TEM), and humidity (HUM). In the multiple linear regression analysis, the mentioned parameters were used as the independent variables, and the Vebe time was the dependent variable. The Vebe time prediction models were evaluated by considering the adjusted R2 and p-values. The selection of the model was based on the largest R2 value and an acceptable p-value (p<0.05). RESULTS : The Vebe time prediction model achieved an adjusted R2 value of 64.14% with a significance level (p-value) of less than 0.05. This shows that the predictive model is adequately described for the dependent variable, and that the model is suitable for Vebe time predictions. Moreover, the significance level of the independent variables is less than 0.05, indicating significant effects on the Vebe time (i.e., the dependent variable). CONCLUSIONS : The Vebe time prediction model developed in this study can be used to estimate Vebe times with an R2 of 63.33% between the measured and predicted values. The proposed Vebe time prediction model is expected to be effectively utilized for the quality control of RCCP mixtures. Moreover, it is expected to contribute to achieving good RCCP construction quality.

The development of technology related to the Fourth Industrial Revolution and the growth of the online market due to pandemic are continuing the growth of the logistics market for product delivery. If it is difficult to deliver the product directly to the customer during delivery, storage and delivery using the unmanned courier box are being carried out. However, existing storage boxes are not actively used due to lack of usability even though they have the advantage of storing goods and delivering non-face-to-face. In addition, existing courier boxes are not prepared for cold chain transportation. The unmanned delivery storage device with ICT cold chain technology should be developed to prepare for the transition to non-face-to-face society, to improve logistics efficiency and meet user's requirements. Also, it is necessary to consider the measures to reduce the safety problems that may occur during the use and maintenance of the automatic system.This study conducted a model-based analysis for the development of unmanned delivery storage devices with ICT cold chain technology, and conducted a study to derive the system development specifications that meet the requirements and secure safety and apply them to the development process.

In order to manufacture a mask to prepare for infectious diseases such as COVID-19 and yellow dust, it is manufactured through the process of input, fusion, cutting, band attachment, defect inspection, and packaging. Domestic mask producers introduced Chinese facilities to keep up with explosive demand due to the rapid spread of COVID-19 in 2020, but serious problems arise in durability. Therefore, domestic processing and tooling companies have developed and supplied molds, but since supply is not smooth compared to demand, research on the development of mask molds with durability reliability is urgently needed to supply masks stably. This technology development aims to supply a mask with excellent quality to a market by applying dots capable of welding and re-painting to a mold for cutting applied to a mask manufacturing process and developing dots optimized for paper angles.

해사 분야의 대표적 안전법인 ｢해사안전법｣은 2011년 전부개정을 통하여 (구)｢해상교통안전법｣에서 제명을 변경하고, 해사안전 분야의 기본법으로 재편 된 바 있다. 그럼에도 불구하고 여전히 ｢해사안전법｣은 해사안전 전반을 아우 르는 기본법적 기능을 하지 못하고 있으며, 해상교통 환경변화에 긴밀하게 대 응하는데도 한계가 있어 ｢해사안전법｣의 기능 제고가 필요한 상황이다. 특히 급격한 해양공간의 활용방식의 변화, 해사안전기술의 발전 등은 기존의 해사안 전법제의 변화는 물론 확장까지도 요구하고 있다. ｢해사안전법｣이 기본법으로 전부개정되고 10여년이 경과한 지금, ｢해사안전법｣의 체계적·내용적 문제점을 전반적으로 분석하고 법 전반에 걸친 입법적 개선방향을 모색하는 것은 매우 중요하다. 본 논문에서는 2011년 전부개정 이후의 ｢해사안전법｣의 발전연혁과 최근의 입법동향을 분석한다. 이후 ｢해사안전법｣의 기본법적 기능의 한계가 나타날 수 밖에 없는 법체계적인 문제점을 검토하고, 해사안전법체계 개편의 필요성을 도 출하였다. 또한 ｢해사안전법｣의 규율사항에 대해 규제법적 차원에서 각 제도가 적절한 형태로 입법되어 있는지를 검토하고 정비가 필요한 대표적인 항목을 제 시하였다. 이러한 논의를 바탕으로 향후 해사안전 확보를 위하여 ｢해사안전법｣ 체계 개편의 필요성과 분법방안은 물론, 해사안전 분야에서 가장 시급한 사항 에 대한 법제정 필요성 등 입법적 과제를 제안하였다. 구체적으로 ｢해사안전법 ｣은 ‘(가칭)해사안전기본법'과 ‘(가칭)해상교통안전법'으로 분법할 필요가 있으 며, 새로운 환경변화에 따라 장기적 기반조성 차원에서 ’(가칭)해상교통로 구축 및 관리에 관한 법률’제정이 필요하다. 이와 함께 ｢해사안전법｣ 분법(안)과 제 정법(안)에 포함되어야 하는 사항도 함께 제시하였다. 이러한 논의들은 해사안 전법체계 전반에 걸친 체계를 정립하며, ｢해사안전법｣의 기능을 제고하고, 해 사안전을 위한 정당하고 합리적인 규제가 이루어질 수 있게 하고, 해사안전에 필요한 새로운 법적 기반을 효과적으로 구축하는 데 기여할 수 있을 것이다.

본 연구에서는 아시아·태평양전쟁 시기 대한민국 임시정부의 군사외교를 통한 대외적 자율성 확보 정책을 분석하였다. 아시아·태평양전쟁은 임시정 부의 활동 공간을 확장시켰다. 전쟁이 발발하자 임시정부는 중국으로부터 한국광복군에 대한 자주성을 회복하고, 미국·영국 등 연합국과 군사합작을 통해 전후 승전국의 지위를 얻고자 하였다. 미국과 영국은 정치적으로는 임시정부를 승인하지 않았으나 군사적으로는 임시정부와 협력관계를 유지 하고자 하였다. 임시정부에서 추진했던 군사외교활동이 국가의 대외적 자 율성 확보 측면에서 갖는 함의는 다음과 같다. 첫째, 대외적 자율성 확보 를 위해서는 대내적 환경의 안정성이 선결되어야 한다. 둘째, 대외환경의 변화는 대외적 자율성을 추구하기 위한 기회이자 위협요인으로 작용할 수 있다. 셋째, 강대국과의 이해관계가 일치되는 요소는 대외적 자율성 확보 에 유리하게 작용한다. 임시정부는 아시아·태평양전쟁이라는 기회를 활용 하여 최종적으로 임시정부에 대한 연합국의 승인을 얻어내고자 하였다.

황해는 유엔해양법협약 제123조에서 다루는 반폐쇄해로 한국-중국-북한이 주요 연안국이다. 황해는 UN이 지정하는 66개의 광역해 양생태계 중 하나로 자원적 가치가 큰 해역이다. 동 협약 제194조에 따라 자원의 사용 및 수익에 관한 연안국의 권리행사는 국가들 간 직접적 또는 지역기구를 통한 간접적 형식의 협력을 통하여 해양환경보호 및 보전에 관한 권리의무를 이행하는 범위 내에서 이뤄져야 한다. 따라서 월경성 환경오염원의 방지대책에 대한 연안국 사이의 법적 공백은 시의성 있게 다뤄져야 할 사안이다. 이와 관련하여 황해광역해양생태계 (YSLME)는 유엔개발계획(UNDP)의 프로젝트로 2기 사업까지 진행되어왔다. 이 과정에서 황해연안생태계에 대한 한·중 공동과학조사를 통한 월경성진단분석(TDA) 그리고 TDA를 바탕으로 한 전략활동계획(SAP) 수립이라는 성과도 있었지만 북한의 참여가 보장되지 못하였고 SAP의 이행에 관한 실효성 있는 관리체제의 부재라는 한계가 있었다. 이에 본 논문에서는 제3기 YSLME 프로젝트가 나아가야 할 방향으로 연안국 간 구속력 있는 조약체결 방안에 관한 연구를 목적으로 한다. 본 연구는 기존 와덴해 삼국 지역협정 성공요소 분석을 통해 한·중·북 지역협력체의 설립과 운영에 관한 단계적 조약화 방안의 타당성을 검증하였다. 단계적 방안을 살펴보면 선행적으로 삼국 공동선언을 통한 ‘황해삼국협력 위 원회의 설립’, ‘황해삼국협력관리 협정(trilateral treaty) 체결’, 골격조약(umbrella convention)을 모(母)조약으로 하는 ‘이행협정(Implementing Arrangement) 체결’의 3단계로 구분하여 볼수 있다. 단계적 입법을 통해 민감한 정치적 변수가 발생하여도 북한의 안정적 참여 유도와 사회 전 계층의 자발적 참여를 통해 황해해양오염 방지 및 대응에 관한 조약의 지속성 및 일관성을 담보할 수 있을 것이라 기대된다.

In this study, the Euro NCAP-based AEB system evaluation simulation was conducted by applying the calculated corrected TTC by road condition estimation of scenarios (CPFA, CPNC, CPLA) of the V2P situation scenario using PC-Crash, a program used for traffic accident analysis. The scenario was evaluated in consideration of the two road conditions. the low-speed conditions among every scenarios avoided collision, but in the medium and high-speed conditions has been collided with pedestrian. It was confirmed that the time point at recognizing pedestrian was lower than set TTC at which AEB system was operated, even though the AEB was operated immediately, a collision occurred due to insufficient braking distance. As in this study, if studies such as V2V, V2P, and V2B considering road friction are actively conducted, it is expected to be useful data for automobile accident prevention and accident analysis.