• Korean Journal of Clinical Laboratory Science
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• v.43 no.2
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• pp.82-88
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• 2011

Mandibular advancement devices (MAD) are therapeutic options for obstructive sleep apnea (OSA). The aim of study was to investigate treatment outcomes of before and after insertion of MAD in OSA patients. We retrospectively selected a total of 13 patients who were diagnosed with OSA syndrome. All sleep-related parameters including apnea-hypopnea index (AHI), oxygen desaturation index (ODI), wake after sleep onset (WASO), total arousal were measured by before and after MAD. The use of MAD proves to be efficient in reducing snoring, apnea-hypopne index ($17.2{\pm}14.6$ vs $20.9{\pm}14.6$), WASO ($27.4{\pm}28.8$ vs $47.9{\pm}43.6$), oxygen desaturation index ($9.0{\pm}11.6$ vs $16.4{\pm}11.7$), stage N3 ($54.8{\pm}45.2$ vs $36.6{\pm}22.0$), REM sleep times ($73.3{\pm}19.4$ vs $66.0{\pm}31.0$) and increases sleep efficiency ($92.6{\pm}6.6$ vs $87.2{\pm}11.2$). The decreases in apnea index based on a reduction in the overall and supine AHI values after MAD therapy were significantly greater for the positional OSA than nonpositional OSA patients. The use of MAD proves to be efficient in snoring, WASO, sleep efficiency, reduced AHI and associated with good compliance of patients.

• Tunnel and Underground Space
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• v.24 no.4
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• pp.325-333
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• 2014

Hydraulic fracturing is the key technology for production of shale gas, which is one of the major unconventional resources. Brittleness index is one of the most important mechanical properties which determine the efficiency of hydraulic fracturing. It was required that the production of shale gas increases with more brittle behavior. Confusingly, there are numerous definitions available for brittleness of rock. This paper summarizes various definitions of brittleness index, and presents correlation analysis of the brittleness indices by using the laboratory experimental results of 48 shale specimens in Korea. Generally, it shows a very weak positive correlation between the brittleness index ($B_1$) which is the ratio of uniaxial compressive strength to tensile strength and the brittleness index ($B_3$) which is calculated by using the Youngs modulus and Poisson's ratio. In addition, the role of Poissons ratio is not clear in defining brittleness indices. In conclusion, standardization of definition for brittleness index is required to apply it to hydraulic fracturing as a parameter for predicting the efficiency.

• Journal of Korean Society for Quality Management
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• v.38 no.3
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• pp.393-407
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• 2010

The purpose of this study is to analysis relative efficiency and efficiency in process of time. Thus we use panel data of 34 local public medical centers between 2003 and 2005 to use DEA and Malmquist analysis. The result of our this study is as flow; first, The results of static efficiency of 34 local public medical centers show 10 CCR model and 23 BCC model which is difference of efficiency by economic of scale. Second, a cause of increased efficiency is not only change of technology but also change of efficiency to management system index show between 2003 and 2005 by Malmquist analysis and contracting-out is higher than direct management between 2004 and 2005. That means efficiency of local public medical centers is their own effort and innovation not government subsidies.

• The Journal of Korea Robotics Society
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• v.13 no.2
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• pp.86-91
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• 2018

This paper presents about design efforts of a human-sized quadruped robot leg for high energy efficiency, and verifications. One of the representative index of the energy efficiency is the Cost of Transport (COT), but increased in the energy or work done is not calculated in COT. In this reason, the input to the output energy efficiency should be also considered as a very important term. By designing the robot with customized motor housing, small rotational inertia, and low gear ratio to reduce friction, high energy efficiency was achieved. Squatting motion of one leg was performed and simulation results were compared to the experimental results for validation. The developed 50 kg robot can lift the weight up to 200 kg, and during squatting, it showed high energy efficiency. The robot showed 71% input to output energy efficiency in positive work. Peak current during squatting only appears to be 0.3 A.

• Journal of Oral Medicine and Pain
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• v.35 no.2
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• pp.135-147
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• 2010

In this study, the objective masticatory efficiency of two groups of temporomandibular disorder patients, pain and sound groups, was compared with that in a normal group using the MAI (mixing ability Index). The subjective chewing ability was evaluated using questionnaires, such as the Food Intake Ability Index (FIA) and Visual Analogue Scale (VAS). The Oral Health Impact Profile (OHIP)-49K of the patients was also examined to measure the oral health-related quality of life. The results were as follows: 1. The MAI, FIA and VAS in the pain group were significantly lower than in the normal and sound groups. This shows that the chewing efficiency of the pain group was lower than the normal and sound groups (P<0.05). However, there was no significant difference between the sound and normal groups. 2. The OHIP-49K for the oral health-related quality of life showed a significant increase in both the pain and sound groups compared with normal group. This means that the oral health-related quality of life was lower in both the pain and sound groups. 3. There was a correlation between the MAI, FIA and VAS (P<0.01) in all subjects (71 persons). The OHIP-49K was associated with the FIA and VAS. 4. There was a correlation between the FIA and VAS (P<0.05) in the sound group but no correlation in the other groups. 5. There was a correlation between the FIA and VAS in all groups. 6. The VAS was increased significantly in the pain group according to the level of pain reduction after treatment (P<0.05). However, there was no significant increase in the MAI, even though there was an improvement in masticatory efficiency. In addition, there was no difference in the FIA and OHIP-49K according to the level of pain reduction after treatment. In this study, it is believed that pain is a main factor decreasing the masticatory efficiency in patients with temporomandibular disorders. Moreover, TMJ sounds decrease the quality of life but do not decrease the masticatory efficiency. Therefore, it is important to control the pain in order to improve the masticatory efficiency in temporomandibular disorder patients. Moreover, managing both pain and sound can improve the quality of life.

• The Journal of the Korea Contents Association
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• v.10 no.5
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• pp.303-313
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• 2010

The purpose of this study is to evaluate the performance efficiency and productivity change of the regional public hospital in Korea. We use DEA(Data Envelopment Analysis) for CCR, BCC model, and MPI(Malmquist Productivity Index). DEA is a useful nonparametric technique for measurement of efficiency of a DMU(Decision Making Unit) and MPI is a evaluation method to measure DMU's productivity change. We utilize 34 regional public hospital's time-series data over 6 years from 2003 to 2008.The results of this study were as follows. First, technical efficiency(TE) shows that approximately 3.6% of inefficiency exists on the regional public hospitals and it reveals that the cause for technical inefficiency is due to scale inefficiency. Second, MPI's results show that regional public hospital made effort to improve total factor productivity change to raise technical efficiency. In order to raise efficiency, the regional public hospitals should deploy internal innovation and the government should support welfare policies.

• Journal of Korea Port Economic Association
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• v.34 no.1
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• pp.51-64
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• 2018

The purpose of this paper is to analyze the productivity change of the Korean shipbuilding industry between 2001-2008 and 2008-2015 by using MPI(Malmquist Productivity Index) to decompose the sources of total factor productivity growth into technical efficiency change, scale efficiency change, pure efficiency change, technical change. The empirical results are as follows. In the first half of the year (2001-2008), productivity increased by 2.8%, which was due to technological advances rather than technical efficiency. In the second half (2008-2015), productivity change declined by -3.4%. This is attributable to the technical efficiency deterioration and technological degeneration caused by a decrease in shipbuilding orders due to the global economic downturn after the global financial crisis and the rise of Chinese shipbuilding industry. In the first half of the period, productivity change was higher than in the second half. Especially, the difference between the two periods is attributed to the technical change and it was proved by statistical verification. The policy implications of this paper suggest that the government and each DMU need to develop new technologies to cope with changes in the global shipbuilding industry environment and strategies to eliminate inefficiencies in order to increase productivity in the future.

• Journal of Digital Convergence
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• v.20 no.4
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• pp.529-539
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• 2022

This study analyzed the index change in efficiency and productivity for the tax reorganization project of the regional headquarters of Korea Asset Management Corporation using panel data for 3 years from 2017 to 2019 using the DEA-Malmquist analysis model. According to the DEA analysis result, the average of the efficiency by the CCR model of the regional headquarters tax reorganization project of the Korea Asset Management Corporation was 0.671 in 2017, 0.772 in 2018, and 0.699 in 2019, and the average of the efficiency by the BCC model was 0.798 in 2017, 0.851 in 2018 and 0.771 in 2019. As a result of analyzing the Malmquist productivity index, the time series average productivity index MPI increased by 4.5%. These results appear to be attributable to the increase in technological efficiency, technological change, and scale-efficiency change rather than the decrease in net efficiency change. Looking at the change in MPI by year, it decreased by 14.6% in 2017-2018, but increased significantly to 27.8% in 2018-2019. Through the results of DEA analysis of specific tax projects of public corporations, each regional headquarters of Korea Asset Management Corporation will be able to contribute to reinforcing business capabilities through mutual benchmarking.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.307-308
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• 2009

We have proposed an index matching film to improve the emitting efficiency of green OLED. Here, SiO2 and TiO2 were selected to coat the green OLED. The structures of index matching film were designed in G1ass/TiO2/SiO2/ITO and SiO2/TiO2/Glass/ITO. Then, these materials were deposited by ion-assisted deposition system. Transmittances of deposited devices were 86.14 and 85.07 %, respectively.

• Journal of Korea Technology Innovation Society
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• v.8 no.3
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• pp.1175-1198
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• 2005

The objective of the study is to verify the relationship between technology valuation indexes and corporate's performance in ventures by business operating periods. The result of the study is expected to be useful in loan evaluation, investment decision, internal management decision making and business improvement. The results of study is as follows. First, in early stage ventures, we find that three major valuation index(technology feasibility, economic efficiency, productivity) are significant ex-ante variables which are discriminating between firms' going concern and firms' failure. Second, in growth stage ventures, we find that three major valuation index(business feasibility, general marketability, technology marketability) are significant ex-ante variables which are discriminating between firms' going concern and firms' failure. Third, in early stage ventures, we find that at least thirty-eight minor valuation index elements are significant ex-ante variables which are discriminating between firms' going concern and firms' failure and in growth stage ventures, thirty-one minor valuation index elements are significant in various analysis' results.