• Tunnel and Underground Space
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• v.29 no.5
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• pp.281-291
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• 2019

In Overseas case, most tunnels in under are or through the river are constructed with shield TBM and the manufacturer orders of related equipment suitable for the project are mode. Accordingly, the client provides the specifications required for the equipment manufacture. In addition, TBM equipment has been operated by those who have completed the expert training program, which for minimizing the risk of equipment operation in construction field corresponding to the mechanized construction. However, in Korea, such a system related to above the program and specifications has not yet been built, which is causing a lot of difficulties in construction field. Therefore, this study investigated the differences in bidding guides provided by mechanized construction in domestic and abroad, and the professional education programs for expert training being conducted from overseas. Futhermore, we will propose the guidelines of essential equipment specification contained in domestic bidding and provide the necessary manual for the professional education program for TBM as the mechanized construction method.

• Geophysics and Geophysical Exploration
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• v.23 no.1
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• pp.38-49
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• 2020

Full-waveform inversion (FWI) is an optimization process of fitting observed and modeled data to reconstruct high-resolution subsurface physical models. In acoustic FWI (AFWI), pressure data acquired using a marine streamer has mainly been used to reconstruct the subsurface P-wave velocity models. With recent advances in marine seismic-acquisition techniques, acquiring multi-component data in marine environments have become increasingly common. Thus, AFWI strategies must be developed to effectively use marine multi-component data. Herein, we proposed an AFWI strategy using horizontal and vertical particle-acceleration data. By analyzing the modeled acoustic data and conducting sensitivity kernel analysis, we first investigated the characteristics of each data component using AFWI. Common-shot gathers show that direct, diving, and reflection waves appearing in the pressure data are separated in each component of the particle-acceleration data. Sensitivity kernel analyses show that the horizontal particle-acceleration wavefields typically contribute to the recovery of the long-wavelength structures in the shallow part of the model, and the vertical particle-acceleration wavefields are generally required to reconstruct long- and short-wavelength structures in the deep parts and over the whole area of a given model. Finally, we present a sequential-inversion strategy for using the particle-acceleration wavefields. We believe that this approach can be used to reconstruct a reasonable P-wave velocity model, even when the pressure data is not available.

• Nuclear Engineering and Technology
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• v.42 no.6
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• pp.662-669
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• 2010

To develop the manufacturing methods for the blanket first wall (FW) of the International Thermonuclear Experimental Reactor (ITER) and to verify the integrity of the joint, Be/Cu mockups were fabricated and tested at the KoHLT-1 (Korea Heat Load Test facility), a graphite heater facility located at the Korea Atomic Energy Research Institute (KAERI). Since Be and Cu joining is the focus of the present study, the fabricated mockups had a CuCrZr heat sink joined with three Be tiles as an armor material, unlike the original ITER blanket FW, which has a stainless steel structure and coolant tubes. Hot isostatic pressing (HIP) was carried out at $580^{\circ}C$ and 100 MPa for 2 hours as the method for Be/Cu joining. Three interlayers, namely, $1{\mu}mCr/10{\mu}mCu$, $1{\mu}mTi/0.5{\mu}mCr/10{\mu}mCu$, and $5{\mu}mTi/10{\mu}mCu$ were applied as a coating to the Be tiles by a physical vapor deposition (PVD) method. A shear test was performed with the specimens, which were fabricated by the same methods as those used to fabricate the mockups. The average values were 125 MPa to 180 MPa, and the samples with the $1{\mu}mCr/10{\mu}mCu$ interlayer showed the lowest value. No defect or delamination was found in the joints of the mockups by the developed ultrasonic test using a flat-type probe with a 10 MHz frequency and a 0.25 inch diameter. High heat flux (HHF) tests were performed at $1.0\;MW/m^2$ heat flux for each mockup using the given conditions, and the results were analyzed by ANSYS-CFX code. For the test criteria, an expected fatigue lifetime about 1,000 cycles was obtained by analysis with ANSYS-mechanical code. Mockups using the interlayers of $1{\mu}mTi/0.5{\mu}mCr/10{\mu}mCu$ and $5{\mu}mTi/10{\mu}mCu$ survived up to 1,100 cycles over the required number of cycles. However, one of the Be tiles in the other two mockups using the $1{\mu}mCr/10{\mu}mCu$ interlayer was detached during the screening test, and others were detached by discharge after 862 cycles. The integrity of the joints using the proposed interlayers was proven by the HHF test, but the other interlayer requires more study before it can be used for the joining of Be to Cu. Moreover, it was confirmed that the measured temperatures agreed well with the analysis temperatures, which were used to estimate the lifetime and that the developed facility showed its capability of the long time operation.

• Clinical and Experimental Pediatrics
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• v.64 no.9
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• pp.480-488
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• 2021

Background: An adequate large-scale pediatric cohort based on nationwide administrative data is lacking in Korea. Purpose: This study established the National Investigation of Birth Cohort in Korea study 2008 (NICKs-2008) based on data from a nationwide population-based health screening program and data on healthcare utilization for children. Methods: The NICKs-2008 study consisted of the Korean National Health Insurance System (NHIS) and the National Health Screening Program for Infants and Children (NHSPIC) databases comprising children born in 2008 (n=469,248) and 2009 (n=448,459) in the Republic of Korea. The NHIS database contains data on age, sex, residential area, income, healthcare utilization (International Classification of Diseases10 codes, procedure codes, and drug classification codes), and healthcare providers. The NHSPIC consists of 7 screening rounds. These screening sessions comprised physical examination, developmental screening (rounds 2-7), a general health questionnaire, and age-specific anticipatory guidance. Results: During the 10-year follow-up, 2,718 children (0.3%) died, including more boys than girls (hazard ratio, 1.145; P<0.001). A total of 848,048 children participated in at least 1 of the 7 rounds of the NHSPIC, while 96,046 participated in all 7 screening programs. A total of 823 infants (0.1%) weighed less than 1,000 g, 3,177 (0.4%) weighed 1,000-1,499 g, 37,166 (4.4%) weighed 1,500-2,499 g, 773,081 (91.4%) weighed 2,500-4,000 g, and 32,016 (5.1%) weighed over 4,000 g. There were 23,404 premature babies (5.5%) in 2008 compared to 23,368 (5.6%) in 2009. The developmental screening test indicated appropriate development in 95%-98% of children, follow-up requirements for 1%-4% of children, and recommendations for further evaluation for 1% of children. Conclusion: The NICKs-2008, which integrates data from the NHIS and NHSPIC databases, can be used to analyze disease onset prior to hospitalization based on information such as lifestyle, eating habits, and risk factors.

• Phonetics and Speech Sciences
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• v.13 no.3
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• pp.53-64
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• 2021

It is known that the voicing contrast for Japanese word-initial stops is primarily realized as differences in the voice onset time (VOT). However, recent studies have reported that voiced stops are more often produced with a positive VOT than with a negative VOT among the younger generation nationwide. It is also known that post-stop F0 is associated with the stop contrast, but the degree of F0 use differs from region to region. This study explores whether the difference in post-stop F0 functions as a perceptual cue to the stop contrast along with VOT. Fifty-five college students who are native listeners from four different regions participated in two or three perception tests. The results show that VOT is a primary cue to the voiced-voiceless distinction of word-initial stops, but that the effect of post-stop F0 on the stop contrast is marginal. The post-stop F0 is involved in perception only when VOT is ambiguous, such that a sound with high F0 is more often perceived as a voiceless stop, but not vice versa. The results of this study indicate that the acoustic parameters associated with the stop contrast are not the same in production and perception, and suggest that other factors such as context, which is not an acoustic characteristic, may also be involved in the stop contrast.

• KIPS Transactions on Computer and Communication Systems
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• v.10 no.7
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• pp.199-204
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• 2021

Digital substation refers to a substation that digitizes functions and communication methods of power facilities such as monitoring, measuring, control, protection, and operation based on IEC 61850, an international standard for the purpose of intelligent power grids. Based on the intelligent operating system, efficient monitoring and control of power facilities is possible, and automatic recovery function and remote control are possible in the event of an accident, enabling rapid power failure recovery. With the development of digital technology and the expansion of the introduction of eco-friendly renewable energy and electric vehicles, the spread of direct current distribution systems is expected to expand. MVDC is a system that utilizes direct current lines with voltage levels and transmission capacities between HVDCs applied to conventional transmission systems and LVDCs from consumers. Converting existing lines in substations, where most power equipment is alternating current centric, to direct current lines will reduce transmission losses and ensure greater current capacity. The process bus of a digital substation is a communication network consisting of communication equipment such as Ethernet switches that connect installed devices between bay level and process level. For MVDC linkage to existing digital substations, the process level was divided into two buses: AC and DC, and a system that can be comprehensively managed in conjunction with diagnostic IEDs as well as surveillance and control was proposed.

• Cross-Cultural Studies
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• v.40
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• pp.159-183
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• 2015

This study examined the issue of criticism in Korean Chinese literature in 1990's. This is transitional time why China introduced a market economy system. It had an important effect on Korean Chinese society not the cultural climate but also literature. Besides, Diplomatic Relation between Korea and China in 1992 gave an impulsion to changing literature. So this study tried to take note of directionality of Korean Chinese literature through the Korean Chinese magazine Literature and Art(Munhakwayesul) and Zhangbaikshan. First issue of Korean Chinese literature in early 1990's is crisis and restoration of criticism genre. At that time criticism faced with what is modernity. Some critics insisted that criticism should to improve. So it was necessary to accept foreign theory. Then they were concerned postmodernism and deideology tendency. What was important thing is that they would find their culture identity. So few critics tried to communicated with world literature. Especially they emphasized communication with Korean writer who lives in other country. Ultimately they thought that Korean Chines literature must get literal universality and ethnic speciality. For example poet Nam-YoungJeon's totem poetry is representative work. The issues of Korean Chines criticism in 1990's are not directivity of literature but also directivity of culture identity. Korean Chines literature had departed from Socialistic realism little by little and had getting diversity. Above all things criticism aimed for international sense and ethnic culture identity.

• International Area Studies Review
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• v.13 no.3
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• pp.527-549
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• 2009

This paper investigates the relation of invert U-shape between the M/B ratio and leverage ratio by market, firm size, and a level of technology of firm. Our sample consists of 510 manufacturing firms continually listed on the Korea Securities Market and Kosdaq Market from January 1, 2001 to December 31, 2008. The total sample consists of the Korea Securities Market(large firms, high technology industry) sample of 2,248(1,816, 1,704) observations and the Kosdaq Market(small and medium firms, high technology industry) sample of 1,632(2,264, 2,376) observations. The empirical results show that the relation of invert U shape appears on the sample of the Kosdaq Market, small and medium firms, and high technology industry. However, the relation doesn't appear on the sample of the Korea Securities Market, large firms, and low technology industry. These mutually different results may be caused by the relatively low M/B ratio of the latter.

• International Area Studies Review
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• v.22 no.1
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• pp.141-159
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• 2018

The study aims to explore the factors that affect the value perception, satisfaction, and frequency of smart phone taxi applications in Shanghai, China, and commuters. According to a survey conducted on the actual use of taxi application, the majority of the customers responded that they have been using taxi apps for more than one or two years, and the results showed that they use taxi apps once or twice a week. It also showed that the actual use of taxi apps varies depending on their age and academic background. Among the value attributes of smart phone taxi applications, the respondents perceived ease of use as the highest at 4.41 points out of 5 point scale, while the risk perception was the lowest at 3.34 points. Finally, when social demographic characteristics and the nature of taxi app use were controlled, the value perception variables had a significant influence on taxi application satisfaction. The higher the perception of service quality, usefulness, and system usability, the higher the satisfaction levels were. In particular, the impact of perceived usefulness and system usability perception was high.

• International Area Studies Review
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• v.22 no.2
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• pp.41-59
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• 2018

After global financial crisis, policy makers in major countries tried to find a new bank recovery and resolution policy. The new policy intends to normalize the market not by bail-out approach in which public funds should be provided bankrupt banks, but by market discipline approach in which unsecured creditors take part in liquidation process. Bail-in system is a new and dominant financial policy after crisis period in resolution regimes led by the government administration. This study tries to analyze the relationship between bail-in system and pro-cyclicality. Empirical analysis has been done by taking the basis of the 8 year data from 2008 to 2015, which is selected from financial statistics information system of Korea Financial Supervisory Service. Accounting and financial data are collected from the dataguide 5.0 between 2008 and 2015. Through the analysis, the effect of bail-out system and bail-in system on pro-cyclicality of total loans did not show the statistically significant relationship. However the effect of bail-out system on pro-cyclicality of SME loans showed the statistically significant relationship, meanwhile the effect of bail-in system on pro-cyclicality of SME loans did not show the statistically significant relationship. In conclusion, bail-in system can be useful policy which improves the support and promotion of SMEs.