• Journal of Advanced Marine Engineering and Technology
• /
• v.19 no.1
• /
• pp.71-81
• /
• 1995

In this paper, a new speed control scheme for induction motor drives that regular sampled PWM and harmonic elimination switching pattern over the full range of output speed is presented. The proposed scheme(hybrid scheme) provides three mode and guarantees smooth voltage boost. A detailed description of the scheme, along with the relalization aspect, is described. Moreover, methods of compensating for dead time and optical transmission system of drive signal are proposed and investigated. Finally, experimental investigation of hybrid scheme is presented.

• The Journal of Korean Academy of Prosthodontics
• /
• v.35 no.3
• /
• pp.517-534
• /
• 1997

It has been held that excessive mechanical forces to the osseous and soft tissues of the TMJ result in joint dysfunction. Understanding the stress pattern on TMJ is very important in TMJ research. But, it is very difficult to measure directly the biomechanical stress distribution in the TMJ when the mandible is loaded. Therefore, stress distribution in the TMJ during functional movement was studied through animal experiment or mathematical model. It was observed and compared the stress distribution occuring in the working and balancing condyle when lower right canine, lower right first molar and lower right second molar were clenched by the three dimensional finite element analysis. Also, stress distribution in the working and balancing condyles were observed and compared when $20^{\circ}$ forward and buccal bite forces were applied to the first molar. The results were as follows : 1. Stress distribution in the condyles during unilateral clenching of the first molar, second molar, canine showed no difference. In the working condyle, tensile force was concentrated on the lateral aspect of the condylar articular surface and condylar neck. And compressive force was concentrated on the anteromedial and lateral aspect of condyle. In the balancing condyle, tensile and compressive forces were concentrated on the lateral aspect of the condylar articular surface and stress transmission to the temporal bone was not observed. 2. When lateral forces were applied to the first molar, tensile forces were concentrated on the medial aspect of the condylar neck and condylar posterior surface in working and balancing condyle. Compressive force was concentrated on the anteromedial and lateral surface of the condyle and stress transmission to the temporal bone was not observed. 3. During unilateral clenching, stress in the working condyle decreased as the occlusal load moved posteriorly while the stress in the balancing condyle increased. when lateral force was applied to first molar, the incremental amount of stress was greater than vertical load. 4. During unilateral clenching, the average balancing/working condyle stress ratio was 2.52. There was a greater concentration of stress in the balancing condyle. The ratio increased as the occlusal load moved posteriorly and decreased considerably when lateral forces were applied to the first molar.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.7 no.4
• /
• pp.611-621
• /
• 1995

The objectives of this study are to find out and to analyze the heat transmission characteristics of the conventional and prefabricated Ondol systems. To compare the thermal characteristics of these Ondol, a real sized Ondol model is set in a chamber. Hot water whose temperature is varied from $45^{\circ}C$ to $60^{\circ}C$ with $5^{\circ}C$ interval is supplied to each Ondol system. At that time the temperature distribution of floor surface, the amount of supplied heat, the heat radiation aspect and the heat loss from the floor to the underground are measured and analyzed simultaneously. As a result, even if the supplied hot water temperature to the prefabricated Ondol panel is lower by about $5^{\circ}C$ than that of the conventional Ondol panel, the net radiant effect is same. Heat radiation efficiency of the prefabricated Ondol panel is over 5% better than that of the conventional Ondol panel. It takes 12 hours for the conventional Ondol and 45 minutes for the prefabricated Ondol, respectively to reach steady state.

• Health Policy and Management
• /
• v.32 no.3
• /
• pp.293-303
• /
• 2022

Background: Coronavirus disease 2019 (COVID-19), which has occurred since the end of 2019, has caused tremendous damage not only in terms of disease and death but also in terms of economy. Accordingly, governments implemented health and quarantine policies to prevent the transmission and spread of COVID-19 and minimize economic effects, and implemented various countermeasures to reduce social and economic damage. However, the damage varies from country to country, and there are differences in the response of each government. Methods: Using 2020 data from the Organization for Economic Cooperation and Development countries, the effectiveness of governments' quarantine and economic policies in response to COVID-19 was calculated, and what factors determine the effectiveness were analyzed. While most of the previous studies analyzed the relationship between the government's quarantine policy and corona transmission and death, this study is characterized by considering the economic aspect in addition. Results: As a result of the analysis, the following results were obtained. First, when economic aspects are not considered, Asian and European countries have similar levels of efficiency, but when economic aspects are taken into account, Asian countries have higher efficiency. Second, population density had a negative effect on the efficiency of each country's policy, and long-term orientation was found to have an important impact when considering the economic aspect. Conclusion: We found that the governance index is an important variable influencing the efficiency, which shows that the effectiveness of government policies in response to the coronavirus depends heavily on the trust relationship between the government and the people.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.7
• /
• pp.741-749
• /
• 2003

In this paper, we investigated the degree of compensation for WDM channel signal distortion due to chromatic dispersion, self phase modulation(SPM) and cross phase modulation(XPM). The considered system is 120 Gbps (3${\times}$40 Gbps) intensity modulation direct detection(IM/DD) WDM transmission system with path-averaged intensity approximation(PAIA) mid-span spectral inversion(MSSI) as compensation method. This system have highly nonlinear dispersion shifted fiber(HNL-DSF) as nonlinear medium in optical phase conjugator(OPC). We use 1 dB eye opening peralty(EOP) in order to evaluate the characteristics of compensation for distorted WDM channels. We confirmed that improvement of transmission distance and performance is achieved by MSSI method to distorted long-haul IM/DD WDM channels due to chromatic dispersion, SPM and XPM. And in the aspect of compensation for distorted pulse due to XPM, the MSSI method is effective to IM/DD WDM transmission system with high fiber dispersion coefficient.

• The Transactions of the Korea Information Processing Society
• /
• v.3 no.6
• /
• pp.1624-1635
• /
• 1996

Palletized color images are the dominant type of the image used on Internet and World-Wide Web. In spite of this, most image compression and progressive transmission algorithm have been designed for continuous-tone images. Pallettize images. Palletized images differ from continuous-tone images in such a aspect that values are lookup table indices a new pyramid structure for compression and progressive transmission of a palletized image. In the proposed pyramid structure, the color of a node at higher level is the one that occupies the most part in 4 sons and each node is represented by a type code and several color codes. Since the proposed method do not exploit spatial correlation in an image, it is ideally applied to lossless compression and progressive transmission of palletized images. We have confirmed this through the experimental results.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.22 no.3
• /
• pp.145-150
• /
• 2022

An analytical model based on a modal transmission-line theory (MTLT) is developed to investigate the optical transmission through metal gratings. This model gives well physical meanings for the transmission as well as for the dispersion relations of the modes responsible for high transmission. These concepts provide accurate information even for real metals used in the visible~near-infrared wavelength range, where surface plasmon polaritons (SPP's) are excited. Furthermore, the dispersion relations allow the nature of the propagation modes to be assessed. The propagation modes are hybrid between Fabry-Pérot like modes and SPP's. It is important to consider different period and aspect ratio of metal gratings in order to determine the nature of the hybrid modes. In this paper, the sensing characteristics and mode propagation phenomena of high-performance plasma bio-sensors that depend on these variables were clearly analyzed.

• Current Research on Agriculture and Life Sciences
• /
• v.31 no.4
• /
• pp.250-255
• /
• 2013

As a renewable nanomaterial, cellulose nanocrystal (CNC) isolated from wood grants excellent mechanical properties in developing high performance nanocomposites. This study was undertaken to compare the reinforcing efficiency of two different CNCs, i.e., cellulose nanowhiskers (CNWs) and cellulose nanofibrils (CNFs) from hardwood bleached kraft pulp (HW-BKP) as reinforcing agent in polyvinyl alcohol (PVA)-based nanocomposite. The CNWs were isolated by sulfuric acid hydrolysis while the CNFs were isolated by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation. Based on measurements using transmission electron microscopy, the individual CNWs were about $6.96{\pm}0.87nm$ wide and $178{\pm}55nm$ long, while CNFs were $7.07{\pm}0.99nm$ wide. The incorporation of CNWs and CNFs into the PVA matrix at 5% and 1% levels, respectively, resulted in the maximum tensile strength, indicating different efficiencies of these CNCs in the nanocomposites. Therefore, these results suggest a relationship between the reinforcing potential of CNCs and their physical characteristics, such as their morphology, dimensions, and aspect ratio.

• (The) Research of the performance art and culture
• /
• no.18
• /
• pp.563-598
• /
• 2009

Gangneung Danoje is a local festival that has its origin in the county festival handed down premodern society. It was designated as an important intangible cultural asset in 1966, and has appreciated as a representative traditional festival of Korea since UNESCO designated it as 'the Oral and Intangible Heritage of Humanity' in 2005. Generally, it is known as a festival which it keeps up the premodern tradition. However, we can know that it is different from the festival performed in the 19 century in its framework and contents if we pay attention to the texts of festival performed in Gangneung today. I think that this change is a result of cultural adaptation by the change of transmission situation, and especially today texts of festival is an result of the pursuit, restoration and reproduction of its traditional form so as to be designated as a cultural asset. In this paper, after I have an accurate grasp of the traditional form of Gangneung Danoje from the present data related to Gangneung Danoje, I will compare its traditional text with the existing text which was reconstructed at the time of being designated as an important intangible cultural asset. To do this work, I verified the composition method of a county festival by investigating a general aspect of county festival in the $Chos{\breve{o}}n$ dynasty, brought out the aspect of its change by comparing its existing text with the procedures and contents of Gangneung Danoje before the Japanese occupation by force, and discussed the matter of its some changes. As a result of my work, I ascertained that the present Gangneung Danoje is very different from the festival transmitted in premodern society in the structure, time and space of festival, and the contents of performance containing the procedures of meeting god, seeing god off, and enjoying god.

• Journal of the Korea Convergence Society
• /
• v.9 no.9
• /
• pp.353-362
• /
• 2018

The purpose of this study is to suggest a professional consensus on the topics that should be dealt with importantly in the movement program for the recovery of cancer patients in Korea. As a result of calculating the importance of the finalized movement program component, First, the opinions about the environment for the promotion of movement were suggested as pleasant facilities, natural lighting, rest room space, facilities aspect of environment friendly space, education about diseases, participation programs, health feedback, information handouts. Second, the opinions on the purpose of the movement program were suggested to promote prevention and early screening of cancer, education, sharing effective treatment methods of cancer patients, cognitive aspect and psychological support for accurate information transmission, stress relief, and improvement of quality of life. Third, the opinions on the consideration of the movement program suggested stress relieving, cancer patient's needs, correct information delivery, quality of life, and participation of cancer patients. Fourth, the problems of the movement program were presented with different physical characteristics, physical inconvenience, the patient side of passive participation, space narrowness and lack, space aspect of program exclusive space etc.