• Journal of Korean Dental Hygiene Science
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• v.5 no.1
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• pp.13-19
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• 2022

Background: In this study, zirconia copings were fabricated by setting clinically acceptable inner values for prostheses using computer-aided design/computer-aided manufacturing (CAD/CAM). The processed copings were evaluated for the marginal and internal fit of each abutment shape with a CAD program using the silicone replica technique. Methods A total of 20 copings was produced by selecting models commonly used in clinical practice. After injecting the sample, the minimum thickness, internal adhesion interval, and distance to the margin line were set to 0.5, 0.05, and 1.00 mm using a dental CAD program, respectively. It was measured using a 2D section function in a three-way program of the silicon replication technology. Although the positions and number of measurements of the anterior and posterior regions differed, nine parts of each pre-tube were designated and measured by referring to a previous study to compare the two samples. Results As a result, the average margin of the mesial, distal, and buccal (labial) surfaces was 59.90 ㎛ in the anterior region and 60.40 ㎛ in the posterior region. The mean axial wall margin was 67.25 ㎛ in the anterior region and 69.25 ㎛ in the posterior region. In occlusion, the anterior teeth (77.70 ㎛), posterior teeth (77.60 ㎛), and both anterior and posterior regions were within the clinically acceptable range. Conclusion The edge and inner fit of zirconia coping manufactured using the CAD/CAM system showed clinically applicable results. To reduce errors and increase accuracy, materials and machine errors that affect the manufacture of prosthetics should be investigated. Based on our results, the completeness of prosthetics could increase if the inner value and characteristics of the material are adjusted when applied in clinical practice.

• Journal of Advanced Navigation Technology
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• v.27 no.4
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• pp.356-364
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• 2023

Sophisticated Air Navigation System has contributed to enhancing the capacity of airspace capacity, leading to an efficient airspace environment. However, it has acted as a factor increasing the probability of collision. When an aircraft fails to maintain vertical separation and instead exhibits lateral positional errors, it does not necessarily lead to a collision. However, as the lateral positional accuracy increases, the randomness of aircraft positions decrease, resulting in an elevated probability of collisions. Consequently, The International Civil Aviation Organization has introduced Strategic Lateral Offset Procedures(SLOP), intentionally deviating aircraft from the centerline of airways. Likewise, South Korea also operates Offset procedure. The Y579 was operated using the Offset before its conversion to a dual airway and the analysis of the Offset track revealed that it was being operated similarly to a unidirectional dual airway. This paper develops a safety assessment methodology applicable to unidirectional dual airways, and applies it to perform a safety assessment of the Y579 Offset procedure.

• Journal of Hydrogen and New Energy
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• v.34 no.4
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• pp.350-357
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• 2023

In this study, the experimental investigation and theoretical analysis were conducted to verify the cooling capacity of the cryocooler used for pre-cooling of hydrogen gas. The effect of the flow rate on a copper pipe attached to the bottom of the cryocooler, which has a coil shape in a hydrogen line, was investigated. Temperature sensors were strategically placed at various positions on the cryocooler to analyze the temperature variations with respect to the flow rate. In this study, the thermal properties of hydrogen for the pressure and temperature were utilized using REFPROP to analyze the cooling capacity of the cryocooler. Based on the experimental results derived from this study, the cooling capacity of the cryocooler for pre-cooling hydrogen gas was considered by calculating the cooling temperature according to the flow rate through theoretical analysis.

• Structural Engineering and Mechanics
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• v.87 no.6
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• pp.529-540
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• 2023

A novel laminated-hybrid-composite-beam (LHCB) of glass-epoxy infused with flyash and graphene is constructed for this study. The conventional mixture-rule and constitutive-relationship are modified to incorporate filler and lamina orientation. Eringen's non-local-theory is used to include the filler effect. Hamilton's principle based on fifth-order-layer-wise-shear-deformation-theory is applied to formulate the equation of motion. The analogous shear-spring-models for LHCB with multiple-cracks are employed in finite-element-analysis (FEA). Modal-experimentations are conducted (B&K-analyser) and the findings are compared with theoretical and FEA results. In terms of dimensionless relative-natural-frequencies (RNF), the dynamic-response in cantilevered support is investigated for various relative-crack-severities (RCSs) and relative-crack-positions (RCPs). The increase of RCS increases local-flexibility in LHCB thus reductions in RNFs are observed. RCP is found to play an important role, cracks present near the end-support cause an abrupt drop in RNFs. Further, multiple cracks are observed to enhance the nonlinearity of LHCB strength. Introduction of the first to third crack in an intact LHCB results drop of RNFs by 8%, 10%, and 11.5% correspondingly. Also, it is demonstrated that the RNF varies because of the lamina-orientation, and filler addition. For 0° lamina-orientation the RNF is maximum. Similarly, it is studied that the addition of graphene reduces weight and increases the stiffness of LHCB in contrast to the addition of flyash. Additionally, the response of LHCB to moving mass is accessed by appropriately modifying the numerical programs, and it is noted that the successive introduction of the first to ninth crack results in an approximately 40% to 120% increase in the dynamic-amplitude-ratio.

• Journal of Korea Entertainment Industry Association
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• v.13 no.7
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• pp.237-245
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• 2019

Entry of women into the higher positions or professions in the fields of entertainment and performing arts has been expanding gradually. Especially, women working in these fields in New York show a dynamic growth and development. As a result, women surviving in a male-dominated world have raised their voices for their human rights to live free from violence, sexuality, slavery, discrimination, etc.. In the entertainment and performing arts, women have been shouting their voices for a long time through the theme, performance process, and the shows. Their voices influenced politics, society, and culture as a whole. The 'MeToo' movement is the result of condensation from their voices. In other words, it is the result of women's voices against sexual harassment or assault in these fields. Starting in Hollywood, the 'MeToo' movement was rapidly spread out online and strongly supported by female leaders and activists in the world. It had a strong influence on the fields of theater and entertainment industry in Korea as well. By recognizing this phenomenon, the contents of this study suggest how and what to continuously increase the value of the 'MeToo' movement in Korea's entertainment industry.

• The Journal of Korean-Japanese National Studies
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• no.33
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• pp.67-111
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• 2017

This article aims to shed light on the wartime labor mobilization of prisoners on a large scale in/across colonial Korea and beyond during the late wartime period. More specifically, this article reveals the logic and mode of mobilization, and sorts out nationwide mobilization cases in colonial Korea. To this end, this article draws on documents and magazines published by the criminal administration of the Japanese Government-General of Korea, as well as the memoirs of prisoners and prison staff including prison administrators and prison chaplains. With the onset of the wartime system, the labor work in prisons centered on the production of military supplies. In 1943, the labor mobilization began to organize the National Protection Corps and dispatch them to remote workplaces. For example, at the requests of the military, prisoners were selected and sent to Hainan Island, while others were sent to military factories and mining fields in the northern part of the country. The authorities specified and adjusted the criteria for imprisonment based on education, physical strength, and other physical and mental conditions. Unconverted ideological offenders were excluded from the mobilization, and instead put under separate control. In preparation for mobilization, the prisoners trained in military drills, received Japanese language education, and underwent assimilation as imperial subjects through the preaching in prison. In order to induce prisoners to volunteer, a legislation system based on the shortening of the prison terms, including the parole system, was also promoted under the wartime system. As a result, prisoners were forced to work harder and faster even under the lowest of wages, poor food and poor housing conditions, and they also filled vacancies in managerial positions by serving as supervisory assistants. The reward system for them, however, did not function properly towards the end of the war, and the number of escapes and infectious outbreaks, as well as mortality rates rapidly increased under the harsh conditions.

• Korean Medical Education Review
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• v.25 no.1
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• pp.45-54
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• 2023

We investigated the work-life balance of clinical professors in charge of patient care, research, and education at medical schools and the demand for work-life balance support according to position (professor, associate professor, or assistant professor). In total, 163 clinical professors completed the consent form and participated in the study. They filled out an online survey consisting of questions about essential characteristics, a work-life balance test, stress, burnout, work-life satisfaction, and work-life balance support needs. We analyzed the results by analysis of variance and cross-tabulation using IBM SPSS ver. 23.0. Differences were found in work-life balance, stress, burnout, and satisfaction with life and work by position. The requirements for support for work-life balance also varied by professional status. Professors had a higher balance between life and work than associate professors or assistant professors. The specific requirements for work-life balance support were also slightly different for each position. Overall, there was a high demand for work process simplification and efficiency for work support, flexible working hours and sabbatical years for family and leisure, and career management consulting and training support for growth. Assistant professors and associate professors had a lower level of work-life balance than professors, as well as higher levels of stress and burnout. Professors' job satisfaction was also higher than that of the other groups. Based on the results of this study, we hope that a healthy work environment can be established through work-life balance support suitable for clinical professors' positions.

• The Journal of Korea Robotics Society
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• v.18 no.1
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• pp.1-9
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• 2023

This paper presents an optimal path planning strategy for aerial searching and surveying of a user-designated area using multiple Unmanned Aerial Vehicles (UAVs). The method is designed to deal with a single unseparated polygonal area, regardless of polygonal convexity. By defining the search area into a set of grids, the algorithm enables UAVs to completely search without leaving unsearched space. The presented strategy consists of two main algorithmic steps: cellular decomposition and path planning stages. The cellular decomposition method divides the area to designate a conflict-free subsearch-space to an individual UAV, while accounting the assigned flight velocity, take-off and landing positions. Then, the path planning strategy forms paths based on every point located in end of each grid row. The first waypoint is chosen as the closest point from the vehicle-starting position, and it recursively updates the nearest endpoint set to generate the shortest path. The path planning policy produces four path candidates by alternating the starting point (left or right edge), and the travel direction (vertical or horizontal). The optimal-selection policy is enforced to maximize the search efficiency, which is time dependent; the policy imposes the total path-length and turning number criteria per candidate. The results demonstrate that the proposed cellular decomposition method improves the search-time efficiency. In addition, the candidate selection enhances the algorithmic efficacy toward further mission time-duration reduction. The method shows robustness against both convex and non-convex shaped search area.

• Journal of ILASS-Korea
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• v.28 no.1
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• pp.1-9
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• 2023

In the cylinder of gasoline direct injection engines, the spray targeting from injectors is of great significance for fuel consumption and pollutant emissions. The automotive industry is putting a lot of effort into improving injector targeting accuracy. To improve the targeting accuracy of injectors, it is necessary to develop models that can predict the spray targeting positions. When developing spray targeting models, the most used technique is computational fluid dynamics (CFD). Recently, due to the superiority of machine learning in prediction accuracy, the application of machine learning in this field is also receiving constant attention. The purpose of this study is to build a machine learning model that can accurately predict spray targeting based on the design parameters of injectors. To achieve this goal, this study firstly used laser sheet beam visualization equipment to obtain many spray cross-sectional images of injectors with different parameters at different injection pressures and measurement planes. The spray images were processed by MATLAB code to get the targeting coordinates of sprays. A total of four models were used for the prediction of spray targeting coordinates, namely ANN, LSTM, Conv1D and Conv1D & LSTM. Features fed into the machine learning model include injector design parameters, injection conditions, and measurement planes. Labels to be output from the model are spray targeting coordinates. In addition, the spray data of 7 injectors were used for model training, and the spray data of the remaining one injector were used for model performance verification. Finally, the prediction performance of the model was evaluated by R² and RMSE. It is found that the Conv1D&LSTM model has the highest accuracy in predicting the spray targeting coordinates, which can reach 98%. In addition, the prediction bias of the model becomes larger as the distance from the injector tip increases.

• Journal of Korean Clinical Nursing Research
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• v.16 no.2
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• pp.57-67
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• 2010

Purpose: The purposes of this study were to compare the level of perception and to identify factors associated with perception on patient safety culture among health care providers working in an operating room(OR). Methods: A cross-sectional survey design was used. Data were collected conveniently from 154 RNs and 116 physicians working in a tertiary hospital in Seoul. Patient safety culture was measured using "The Hospital Survey on Patient Safety Culture" developed by the Agency for Healthcare Research and Quality (AHRQ). Descriptive statistics, t-test, ANOVA, and Spearman rank correlation coefficients were used for statistical analysis with the SPSS version 17.0. Results: The perception level of nurses and physicians on patient safety culture was "moderate" (3.14). Compared to physicians, nurses showed a significantly lower perception on the items of "teamwork within units" (t=-6.904, p<.001) and "overall perception of patient safety" (t=-4.327, p<.001), but had a higher perception about "frequency of events reported" (t=2.769, p=.006). The physicians' professional positions, years of working experience, age, and working hour per week were identified as factors associated with patient safety culture. Conclusion: Level of perception on patient safety culture may vary among health care providers working in the OR. The study finding suggests that a tailored education and training strategies should be considered to develop an effective safety culture for healthcare professionals working in OR.