PURPOSES : Snow removal is one of the principal components in winter road maintenance. The two commonly used methods are mechanical removal and chemical removal. Mechanical removal pushes accumulated snow off the roadway using snow plows. Chemical removal involves the application of chemicals such as NaCl2 (salt), CaCl2, MgCl2, etc., to liquefy the snow on the road. However, chemicals are known to pose negative effects on the environment and road infrastructure, so it is emphasized that only an appropriate amount of chemicals should be applied. Hence, in this study, extensive field experiments were performed to determine the appropriate amounts of chemicals required for each road surface temperature group. METHODS : The experiments were carried out at a road weather proving ground, located in Yeoncheon where road weather (including snowfall) can be artificially created. Four surface temperature groups were predetermined, according to the characteristics of de-icing chemicals on snow. For each temperature group, four different amounts of pre-wetted salt were applied to find the optimal rate for each group. RESULTS : As a consequence, the amount of recommended chemicals for each temperature group was found to be an average of 27.2g/ m2, which is 7.7g/m2 (22%) lower than the corresponding amount presented in the current Korean guidelines. CONCLUSIONS : Applying the results of this study to snow and ice control tasks enables the minimization of the negative impacts of de-icing chemicals, but still maintaining road safety and mobility.

For the smooth implementation and success of smart city projects, it is necessary to recognize that there is a difference in the perception of value judgments or strategic goals among major stakeholders in the planning process. And it is necessary to aim the values and goals of smart cities through reconciliation of these differences. The two major stakeholders in the smart city development project are citizens group and government officials group. Government officials are in charge of establishing and implementing policies for smart city projects, and their value judgments and perceptions influence the policy direction. In these respects, government officials can be an important stakeholder group. Citizens are a group that includes ordinary residents and business owners who live in smart cities and are the ultimate users of infrastructure and facilities. This study investigated the importance perceptions of citizens and government officials, who are the major stakeholders, about the core values and strategic goals that the smart city project aims. Responses were collected using a structured questionnaire to which the AHP methodology was applied. And the priority of perceptions for constituent items was compared for each stakeholder group. Through the comparative analysis results, it was empirically confirmed that there is a difference in the values and goals pursued by the smart city project between stakeholder groups. As an empirical study on the stakeholders of the smart city project, this study is meaningful in contributing to the theoretical development in that it suggests that the conceptual structural model of the smart city strategy system presented in previous studies can be applied in practice.

This study investigated the responses of Eremogone juncea flowering characteristics to exogenous 6-benzylaminopurine (BAP) and gibberellic acid3 (GA) treatments. Overwintered E. juncea plants were sprayed with seven treatments: no hormones; 200, 400, and 800 mg·L-1 BAP; and 200, 400, and 800 mg·L-1 GA. All treatments showed 100% flowering, and the exogenous BAP and GA treatments did not affect the time to flowering, whereas the hormone treatments influenced floral organ development. BAP significantly decreased the floret diameter and inflorescence length with increasing BAP concentration, although the 400 and 800 mg·L-1 BAP treatments showed similar values. BAP also caused abnormal flowers with a large gynoecium and stamens with small anthers and short filaments. However, GA significantly increased the floret diameter and inflorescence length, although 800 mg·L-1 GA treatment did not affect the floret diameter. In the vegetative parameters, the leaf length tended to increase as the GA concentration increased. These results indicate that BAP and GA affect the flowering quality of E. juncea and can enhance the value of cut flowers, such as flower size and inflorescence length, by making the flowers larger overall.

The Army, Navy, and Air Force are currently making various efforts to apply defense IoT technology by reflecting the characteristics of each military. However, there are concerns that comprehensive collection, management, and analysis may be limited because each military has no overlapping system or guaranteed interoperability of data, and there are inefficient aspects in terms of using and investing a limited defense budget. In this study, evaluation items and priorities for pilot projects were selected by applying Delphi technique and AHP method to determine which projects are preferentially effective when commonly applied in terms of Army, Navy, and Air force. As a result of the analysis, the project basis and driving force, project feasibility, performance and ripple effect, redundancy and connection were identified in the order of IoT-based small detachment units and unmanned base construction, intelligent smart unit, smart ground ammunition depot, and smart training management system. According to the comprehensive results reflecting the weights of each evaluation item, the fact that small detachment units and unmanned base construction project are recognized as the first project to be applied to the Army, Navy, and Air Force is a valid approach to be effective while each military is burdened with personnel management because of the reduction of manpower. Through the research results, it is expected that the direction of application to the policy of the defense IoT project can be confirmed in terms of efficient use of limited budgets.

This study is a follow-up paper on “Development of flipped learning class model for nail beauty education” published by Seol (2022). This model was conducted from March to June 2022 for 70 students taking the “Nail color design 1” course. After 15 weeks of class, a survey of the students’ perceptions of flipped learning and their self-evaluation of goal achievement was conducted, which was composed of questionnaires using a 5-step Likert scale. 15 questions were designed to evaluate the students’ satisfaction with their experience and class operations; 4 questions to evaluate whether the class goal had been reached through flipped learning; and 9 questions to evaluate the students’ perceptions of flipped learning. As a result of applying this model to theoretical and practical nail beauty classes, it was confirmed that flipped learning helped students better understand the content and had a positive effect on learning, while the subject’s educational goals were also achieved. By evaluating the students’ perceptions of flipped learning, we may conclude that they experienced learning satisfaction and perceived the approach positively. Moreover, they have expressed a desire for additional flipped learning. This study is thus meaningful in confirming the procedure’s effectiveness by applying the flipped classroom model to theoretical and practical subjects with a focus on the nail beauty field, and showing how it achieved students’ positive perceptions and educational goals.

Various optical devices are utilized to fire artillery in Korean Army. To transport and store the optical devices, some cases are made up for a set. The covers of cases are made of Glass Fiber Reinforced Plastic(GFRP) and resin. Because of materials of case, it has a disadvantage in productivity for manufacturing covers and assembling components. In this study, ABS resin is presented for alternative and verify possibility through FEM analysis. Comparing with GFRP, max stress-ratio of ABS is decreased 19.6% for bottom, 8.2% for side and 25.4% for edge. Also each strain is changed 17.3%, 180.3% and 17.7%. According to the research results, ABS resin is considered possible for alternative. And the number of components is decreased for around 73.8%.

Failure to comply with the performance test requirements for the centrifugal pumps at power plants often results in performance dissatisfaction as a result of field tests. This study proposed a method of reducing the uncertainty of the field test results by evaluating the systematic error in the measurement system caused by failure to follow the test requirements using the computational fluid dynamics(CFD) technique. As a result of the evaluation of the systematic error and reflecting it in the performance test data, it was confirmed that the error occurred at a constant rate with respect to the flowrate and that the pump, which showed a difference in performance actually had the same performance.

Dimethoxymethane, also known as methylal, is an oxygenated additive that contains approximately 42% oxygen content and is soluble in diesel fuel. Experiments were conducted by using the five kinds of blended fuels with different volumetric percentage of DMM in a diesel fuel. The test engine was used four stroke, single cylinder, DI diesel engine. Also, data was collected at 24 kinds of various engine speed-load conditions. The aim of this study was to examine the effects of the addition of oxygenated additive to diesel fuel on the emissions and the performance. Smoke emissions of all DMM blended fuels were reduced substantially in comparison with diesel fuel. In addition, this study showed that simultaneous reduction of NOx and smoke emissions could be achieved by oxygenated additive and EGR method that was applied to decrease smoke emissions increasing with NOx emissions reduction.

The study was aimed to investigate the operational meal costs by kindergarten size in Seoul and to analyze recognition for optimal meal prices. A survey (31.6% recovery rate) was conducted on all kindergartens (779 kindergartens) in Seoul on April 2021 using descriptive analysis, t-test, and dispersion method. A price sensitivity measurement (psm) method was used to determine optimal meal prices. Result showed an average food cost for kindergartens of 2,647 won, an average labor cost of 605 won, an average operating cost of 146 won, and the total meal cost of 3,506 won. Total meal cost decreased with increasing kindergarten size (p<0.001). On the other hand, kindergartens with more students decreased the ratio of food cost to total meal cost, and operating cost and labor costs (p<0.001) increased. The optimal price of kindergarten operators' meal cost (OPP) was KRW 3,673. Furthermore, the analysis showed the sensitivity of operators' meal costs to kindergarten size was insignificant.