• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.50 no.2
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• pp.70-79
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• 2024

Objectives: The surgical guide is a static computer-assisted device used for implant surgery planning and guidance. By taking an impression and referring to the patients' three-dimensional computed tomography scan of the desired implant site, a surgical guide can be created. During surgery, the surgical guide aids in achieving the designed implant placement position and direction. We examined and evaluated the long-term clinical outcomes of implant surgery using surgical guides. Materials and Methods: This study investigated a total of 15 patients with 32 implants that were placed using surgical guides from 2009 to 2011 with a mean follow-up period extended beyond 10 years. Patient demographics and implant survival rates were recorded. We analyzed marginal bone loss (MBL) by assessing the radiographs acquired at installation, three months after installation, and one month, one, two, and five years after prosthesis delivery. Results: The mean patient age was 57.33 years at implant placement. Of the 32 implants, five implants were placed in the anterior region and 27 implants were in the posterior region. Six implants failed and three of them were replaced, resulting in an 81.25% survival rate. The mean follow-up period was 10 years and nine months. Mean MBL compared to post-installation was significantly higher than at three months after installation, and one month, one, two, and five years after prosthesis delivery. Mean MBL at three months after installation, and one month, one year, and two years were significantly higher compared to the previous visit (P<0.05). However, MBL at five years after prosthesis delivery did not differ significantly compared to at two years. Conclusion: In this study, implant rehabilitation assisted by surgical guides exhibited favorable survival rates. With the limitation of the sample amount in this study, further research and more samples are required to evaluate the long-term clinical effectiveness of surgical guides.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.3
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• pp.393-403
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• 2014

Objectives: Korean Occupational Safety and Health Agency(KOSHA) intended to provide guidance to respirator program administrators on respirator selection. The purpose of this project is to suggest a preliminary respirator selection guide(PRSG) for the final guidance certified by KOSHA for the correct selection of respirators in the workplace. Materials: This PRSG was made on the based of current status of respirator usage including respirators available in Korea, foreign documents search and so on. PRSG was partially modified NIOSH pocket guide to chemical hazards, 3M Respirator Protection Resource Guide(RPRG) and OSHA Assigned Protection Factor(APF) rulemaking. Results: Respirators for chemicals having Korean Occupational Exposure Limits(KOELs) can be recommended in PRSG. For the others chemicals that have no KOELs, PRSG tells you what respirators you can select, using a simple step-by-step approach after health hazard assessment like HSE procedure. Conclusions: PRSG helps you to decide the right level of protection for a given hazardous substance and how to select the right respirators. PRSG is thus expected to reduce significant misuses of respirators for the work environment.

• Journal of Auto-vehicle Safety Association
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• v.14 no.1
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• pp.55-61
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• 2022

Along with global environmental issues, the size of the electric vehicle market has recently skyrocketed. Various efforts have been made to extend mileage, one of the biggest problems of the electric vehicles, and development of batteries with high energy densities has led to exponential growth in mileage and performance. However, proper thermal management is essential because these high-performance batteries are affected by continuous heat generation and can cause fires due to thermal runaway phenomena. Therefore, thermal management of the battery is studied through the optimal design of the guide vanes, while utilizing the existing battery casing to ensure the safety of the electric vehicles. A battery from T-company, one of a manufacturer of the electric vehicles, was used for the research, and the commercial CFD software, ANSYS CFX V20.2, was used for analysis. The guide vanes were derived through optimal design based on a genetic algorithm with flow analysis. The optimized guide vanes show improved heat removal performance.

• International conference on construction engineering and project management
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• 2011.02a
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• pp.93-98
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• 2011

The application of knowledge management concepts as a way to improve project success is an emerging topic for project management researches around the world. The Construction Extension to the PMBOK^® Guide Third Edition documents the knowledge and practices that are generally recognized as good practices for managing engineering and construction projects. However, it is not unusual to see that engineering and construction projects suffer from poor performance. Based on a critical literature review, a theoretical framework is developed for the application of knowledge management in engineering and construction projects. This framework is subsequently applied as a lens to examine the construction extension to the PMBOK^® Guide, aiming to identify the key characteristics of knowledge management in this standard. This research also aims to highlight those aspects of the construction extension to the PMBOK^® Guide that can be improved from the knowledge management perspective. Recommendations are made to improve this standard by means of applying knowledge management concept so that better project outcomes can be achieved.

• Journal of Digital Convergence
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• v.18 no.10
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• pp.437-442
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• 2020

Information boards installed in Seoul subway stations are currently in four languages: Korean, English, Chinese, and Japanese. Informational announcements are provided to inform the main information or operation information through the LCD monitor installed in the train and in Korean. However, users are confused because the subway guide board screen displays advertisements more heavily than driving information As a research method, we grasped the current status and problems of the subway guide board installed on the Seoul subway, and presented an improved new subway guide board drafts. An online survey was conducted on 67 people, ranging from teens to 60s who mainly use the Seoul Metro. As a result of the study, the screen design is different for each boarding route, so it is necessary to unify the subway guide board that provides only necessary information. In particular, since the user transfers the subway several times in order to move from place to place, the subway guide board design should function as an emergency disaster guide or boarding information, not an advertising signboard.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.4
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• pp.419-426
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• 2023

Objectives: This study aims to develop an Occupational Safety and Health (OSH) guide for the safe cleaning of contaminated machinery, equipment, and parts used in the electronics manufacturing process. Methods: A literature review, field investigations, and discussions were conducted. An initial draft of an OSH guide was developed and reviewed by experts with significant experience in maintenance work in the electronics manufacturing process in order to refine the guide. Results: Workers involved in cleaning processes with chemicals, solvents, and abrasive blasting can face exposure to a wide range of chemicals, abrasives, and noise. Identifying potential risks associated with each cleaning technique was an essential first step toward enhancing safety measures. The OSH guide comprises approximately eleven to twelve sections spanning 20-25 pages. It includes engineering and administrative protocols systematically organized to address the necessary actions before, during, and after cleaning tasks, depending on the technique. It is recommended that airline respirator masks be used in conjunction with an air purification system to ensure adherence to air quality standard "D" for atmosphere level. The use of an oil-free air compressor is advised, preferably a stationary model that does not rely on fuel sources like diesel. Conclusions: This OSH guide is designed to protect workers involved in maintenance activity in the electronics industry and aligns with global standards, such as those from the International Organization for Standardization (ISO) and Semiconductor Equipment and Material International, ensuring a higher level of safety and compliance.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.1-15
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• 2004

Due to recent scientific innovations in mulberry cultivation, leaf yield has been increased manifold. However, with successive leaf harvest, a quantum drop in leaf yield and quality has been noted. This inturn has affected the silkworm rearing and farmers suffered by the frequent crop failures. This is mainly due to nutrient deficiencies in mulberry leaf. Moreover, no complete information is available about hunger signs of nutritional disorders, analytical diagnosis and critical levels of nutrients required. The present paper, thus, may serve as an important nutrient guide for identification of hunger signs, leaf nutrients status under deficiency and critical levels of the elements namely N, P, K, Ca, Mg, S, B, Cu, Fe, Mn and Zn requirements for higher leaf yield and quality. The leaf nutrient status provided may help chemist for correcting the soil status. Besides, an integration of mulberry intercropping with legumes and applications of neem and castor oil cakes, VA-mycorrhizal inoculation, biofertilizer and vermicompost are suggested as integrated nutrient management for sustainable sericulture industry. Based on the information described in this paper, a model needs to be framed for maintaining continuous supply of nutrients to obtain desired quantity and quality of mulberry leaf for successful silkworm cocoon crop and increasing overall silk productivity.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.12
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• pp.1281-1286
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• 2013

In this paper, a miniaturized stage with two prismatic-prismatic joints (2-PP) type parallel compliant mechanism driven by piezo actuators is proposed. This stage consists of two layers which are a motion guide layer and an actuation layer. The motion guide layer has 2-PP type parallel compliant mechanism to guide two translational motions, whereas the actuation layer has two leverage type amplification mechanisms and two piezo actuators to generate forces. Since the volume of the stage is too small to mount displacement sensors, the piezo actuators embedding strain gauge sensors are chosen. With the strain gauge-embedded piezo actuators, a semi-control is implemented, which results in hysteresis compensation of the stage. As the results, the operating range of $30{\mu}m$, the resolution of 20 nm, and the bandwidth of 400 Hz in each axis were obtained in the experiments.

• Current Optics and Photonics
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• v.2 no.3
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• pp.269-279
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• 2018

We are currently investigating the feasibility of a 1.6 m telescope with a laser-guide star adaptive optics (AO) system. The telescope, if successfully commissioned, would be the first dedicated adaptive optics observatory in South Korea. The 1.6 m telescope is an f/13.6 Cassegrain telescope with a focal length of 21.7 m. This paper first reviews atmospheric seeing conditions measured over a year in 2014~2015 at the Bohyun Observatory, South Korea, which corresponds to an area from 11.6 to 21.6 cm within 95% probability with regard to the Fried parameter of 880 nm at a telescope pupil plane. We then derive principal seeing conditions such as the Fried parameter and Greenwood frequency for eight astronomical spectral bands (V/R/I/J/H/K/L/M centered at 0.55, 0.64, 0.79, 1.22, 1.65, 2.20, 3.55, and $4.77{\mu}m$). Then we propose an AO system with a laser guide star for the 1.6 m telescope based on the seeing conditions. The proposed AO system consists of a fast tip/tilt secondary mirror, a $17{\times}17$ deformable mirror, a $16{\times}16$ Shack-Hartmann sensor, and a sodium laser guide star (589.2 nm). The high order AO system is close-looped with 2 KHz sampling frequency while the tip/tilt mirror is independently close-looped with 63 Hz sampling frequency. The AO system has three operational concepts: 1) bright target observation with its own wavefront sensing, 2) less bright star observation with wavefront sensing from another bright natural guide star (NGS), and 3) faint target observation with tip/tilt sensing from a bright natural guide star and wavefront sensing from a laser guide star. We name these three concepts 'None', 'NGS only', and 'LGS + NGS', respectively. Following a thorough investigation into the error sources of the AO system, we predict the root mean square (RMS) wavefront error of the system and its corresponding Strehl ratio over nine analysis cases over the worst ($2{\sigma}$) seeing conditions. From the analysis, we expect Strehl ratio >0.3 in most seeing conditions with guide stars.

• Journal of the Korean Society of Safety
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• v.28 no.1
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• pp.117-124
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• 2013

Emergency operating procedures(EOPs) of nuclear power plants should be described considering the cognitive capability and limitation of operators and provide appropriate information in the aspect of human factors. Procedures which doesn't consider cognitive characteristics of operators can become causes of human errors. In previous researches, in order to reduce these problems related to the description of EOP, an improvement suggestion for EOP writer's guide has been proposed, which is reflected human factors aspects that should be considered when describing EOPs. The proposed items, however, have a necessity to be validated because it was listed from various documents such as standards and guidelines without any special validation process. For that reason, in this study, a validation process were performed to show that procedures, which are described in compliance with the requirement items proposed in the improved EOP writer's guide, have positive effects in the aspects of human errors and performance comparing with previous procedures. Experiments were performed to compare the performances of two tasks which are described in compliance with each writer's guide of before and after the improvement During each task was performed in experiments, changes of physiological responses such as EEG and ECG were measured to evaluate the cognitive workload and the stress of operators in each task. And also, as the performance, frequencies of errors and cognition speeds of each task were evaluated. In the results of the experiment, the portions of the ${\beta}$ wave decreased in the tasks overall after the improvement. In the case of ECG, change rates of the mean of R-R interval were decreased in the tasks after improvement. In the results of the performance, the cognition and the response time of the tasks after the improvement were predominant with statistical significancies. Error times in the tasks after improvement were decreased or same to the tasks before improvement. Conclusively, it was validated that the procedures were described in compliance with the improved EOP writer's guide had effects on the reduction of human errors and improvement of performance.