• Tunnel and Underground Space
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• v.16 no.3 s.62
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• pp.241-250
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• 2006

Ice ring formation, one of the core techniques in LNG storage in a lined rock cavern, is investigated through hydro-thermal coupled analysis. An ice ring acts as a secondary barrier in case of leakage of cryogenic liquid and as a primary barrier for groundwater intrusion into an LNG cavern. Therefore, the thickness and location of the ice ring are crucial factors for the safe operation of an LNG storage cavern, especially for maintaining the integrity of a primary barrier composed of concrete, PU foam, and steel membrane. Through numerical analyses, the position and thickness of the ice ring are estimated, and the temperature and groundwater level are compared with measured values. The temperature md groundwater level by numerical analyses show good agreement with the field measurements when temperature-dependent properties and phase change are taken into account. The schemes used in this paper can be applied for estimation of ice ring formation in designing a full-scale LNG cavern.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.3
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• pp.271-277
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• 2019

Objectives: A 46-year-old woman who had worked on cleaning stainless steel containers with Initially unknown powders died from acute silicosis. To determine whether the acute silicosis was related to his work environment, we conducted exposure assessment the level of exposure to respirable crystalline silica(RCS) during cleaning stainless steel containers with unknown powders. Methods: The exposure assessment of RCS were undertaken according to the National Institute for Occupational Safety and Health(NIOSH) method 7500. The components of the unknown powder were analyzed using X-ray Diffraction. Results: The unknown powder was found to be natural diatomaceous earth, which contained 12% and 9% quartz and cristobalite, respectively, crystalline silica. In the case of cleaning stainless steel containers with diatomaceous earth powder, the primary measurement resulted in 1.3 times higher occupational exposure limit of MOEL(in sum of quartz and cristobalite concentration) and 3.9 times higher in secondary measurement. The workbench was equipped with a local exhaust system, but because there was no hood at the end of the duct, the wind speed at the opening of the duct was 12 m/sec, whereas the controlled wind speed at the working position was only 0.3 m/sec below the legal standard. Conclusions: There is an urgent need to install the hood, conduct safety and health education for employers and workers, and periodically monitoring and manage the working environment.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.42
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• pp.21.1-21.6
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• 2020

Background: Fibula free flap mandible reconstruction is the standard procedure after wide resection of the mandible. Establishment and maintenance of normal occlusion are important in mandible reconstruction both intraoperatively and after surgery. However, scar formation on the surgical site can cause severe fibrosis and atrophy of soft tissue in the head and neck region. Case presentation: Here, we report a case of severe soft tissue atrophy that appeared along with scar formation after mandibular reconstruction through the fibular free flap procedure. This led to normal occlusion collapse after it was established, and the midline of the mandible became severely deviated to the affected side that was replaced with the fibula free flap, leading to facial asymmetry. We corrected the malocclusion with a secondary operation: a sagittal split ramus osteotomy on the unaffected side and a sliding osteotomy on the previous fibula graft. After a healing time of 3 months, implants were placed on the fibula graft for additional occlusal stability. Conclusion: We report satisfactory results from the correction of malocclusion after fibula reconstruction using sliding fibula osteotomy and sagittal split ramus osteotomy. The midline of the mandible returned to its original position and the degree of facial asymmetry was reduced. The implants reduced difficulties that the patient experienced with masticatory function.

• Cross-Cultural Studies
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• v.39
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• pp.329-354
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• 2015

The major goals of this paper are to identify the degree into which the meanings of 'see' verb can be extended, focusing on the extended meanings shown in the expressions that denote our instinctive actions for survival, such as eating or drinking, etc., and to clarify the doubt on whether any syntactic pattern can be associated with the meaning in the process of meaning extension of 'see' verb. For doing this task, this paper picked out 2,000 examples randomly from COCA (Corpus of Contemporary American English), in which the verb 'see' is used. This paper classified the sentences into thirteen different sentence types, according to the syntactic patterns. This research showed that these thirteen syntactic types lead us to figure out the process of the meaning extension of the verb 'see'. With this result, this paper made an attempt to provide the four steps toward the meaning extension of verb 'see'. The verb 'see' in the first step denotes the meaning of purely seeing the visualized objects. This verb in the second step expresses the shifted function, under which the agent in the subject position takes the seeing action as a secondary task in order to carry out other main task. The verb in the third step denotes the extended meanings irrelevant to the seeing action, because the sentences on this step do not contain any visualized objects. In the last step this verb functions as conventional implicature whose meaning does not contribute to the whole meaning of a sentence. In addition, this paper identified that the syntactic properties are deeply associated with the process of meaning extension of the verb 'see', and tried to formalize this relationship between the syntax and semantics within the framework of Construction Grammar based on A. Goldberg.

• Journal of The Korean Astronomical Society
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• v.51 no.6
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• pp.207-214
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• 2018

A coelostat is often used for solar observations, because it corrects the image rotation automatically by guiding sunlight into a fixed telescope with two plane mirrors. For the purposes of education and spectroscopic observation, the solar group at Seoul National University (SNU) plans to develop the SNU coelostat (SNUC) and install it in the SNU Astronomical Observatory (SAO). Requirements of the SNUC are < 1" positioning accuracy with 30 cm beam size on the entrance pupil in the compact dome. To allow for installation in the small dome, we design a compact slope type coelostat with a 45 cm primary plane mirror and a 39 cm secondary plane mirror. The motion of the SNUC is minimized by fixing the position of the slope frame. Numerical simulations of the available observational time of the designed coelostat shows that the sun can be observed ay all times from June to early August and at least three hours in other months. Since the high accuracy driving motors installed in the SNUC can be affected by external environment factors such as humidity and temperature variations, we design a prototype to test the significance of these effects. The prototype consists of a 20 cm primary plane mirror, a 1 m slope rail, a direct drive motor, a ballscrew, a linear motion guide, an AC servo motor, a reduction gear and a linear encoder. We plan to control and test the accuracy of the prototype with varying atmospheric conditions in early 2019. After testing the prototype, the SNUC will be manufactured and installed in SAO by 2020.

• Korean Medical Education Review
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• v.21 no.1
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• pp.41-50
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• 2019

The aim of this study is to analyze the current status and performance evaluation systems of faculty in Korean medical colleges and professional graduate medical schools (called medical schools). We developed a research tool based on previous studies and distributed it to 40 medical schools from July to October 2017. The response rate was 100%. We calculated the number of faculty members and analyzed the faculty evaluation systems and awareness according to national and private medical schools. As of 2017, the number of medical faculty in Korea was 11,111 (4,973 faculty were employed by their alma mater, which is 44.76% of the total), with non-medical doctor faculty accounting for 754 of the total. The medical schools reflect research achievements as most important for re-appointment and screening to promote faculty, and the area of education is secondary excepting clinical faculty of private medical schools. However, important issues in the faculty evaluation deal with the relevance of research achievement and the need for qualitative assessment. Some medical schools revised or have been revising the faculty evaluation system in areas such as minimum standards of education for promotion and separation of promotion and tenure review. Opening non-tenure track lines for faculty show positive effects such as increasing the number of positions for hire and easing the financial burdens of medical schools. Downfalls include inconsistencies between the responsibilities and actual practices of tenure not being available and the instability of faculty's status. In conclusion, medical schools need to prepare a faculty evaluation system that fits the position of faculty members and attempt to establish a reasonable compensation system.

• Journal of Home Health Care Nursing
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• v.27 no.3
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• pp.356-371
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• 2020

Purpose: This study was conducted to assess the working conditions of home health nurses in hospital-based home health institutions nationwide. Methods: A secondary data analysis study was conducted based on the survey data on the working conditions of home health nurses, jointly conducted by the Korean Home Health Care Nurses Association and the Academic Society of Home Health Care Nurses in September 2020. Results: Of the home health nurses respondents, 82.4% worked in tertiary hospitals and general hospitals. Most of the working hours of home health nurses were 40 hours a week. Traffic accidents accounted for a significant proportion of accidents experienced by the home health nurse while performing their duties. Most of welfare and benefits systems applicable to home health institutions were in place. The time allocated to provision of home health nursing services was usually more than 30 minutes but less than 1 hour. The type of position of the individual in charge of home health care differed according to the type of medical institution. Conclusion: It is recommended that continuous investigation and analysis be conducted in order to establish a direction for improvement of home health nurses' working conditions, based on the related accumulated data.

• Journal of Microbiology and Biotechnology
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• v.31 no.6
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• pp.882-889
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• 2021

In order to use an enzyme industrially, it is necessary to increase the activity of the enzyme and optimize the reaction characteristics through molecular evolution techniques. We used the error-prone PCR method to improve the reaction characteristics of LipCA lipase discovered in Antarctic Croceibacter atlanticus. Recombinant Escherichia coli colonies showing large halo zones were selected in tributyrin-containing medium. The lipase activity of one mutant strain (M3-1) was significantly increased, compared to the wild-type (WT) strain. M3-1 strain produced about three times more lipase enzyme than did WT strain. After confirming the nucleotide sequence of the M3-1 gene to be different from that of the WT gene by four bases (73, 381, 756, and 822), the secondary structures of WT and M3-1 mRNA were predicted and compared by RNAfold web program. Compared to the mean free energy (MFE) of WT mRNA, that of M3-1 mRNA was lowered by 4.4 kcal/mol, and the MFE value was significantly lowered by mutations of bases 73 and 756. Site-directed mutagenesis was performed to find out which of the four base mutations actually affected the enzyme expression level. Among them, one mutant enzyme production decreased as WT enzyme production when the base 73 was changed (T→ C). These results show that one base change at position 73 can significantly affect protein expression level, and demonstrate that changing the mRNA sequence can increase the stability of mRNA, and can increase the production of foreign protein in E. coli.

• Biomolecules & Therapeutics
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• v.30 no.1
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• pp.19-27
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• 2022

Epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase widely expressed in many cancers such as non-small cell lung cancer (NSCLC), pancreatic cancer, breast cancer, and head and neck cancer. Mutations such as L858R in exon 21, exon 19 truncation (Del19), exon 20 insertions, and others are responsible for aberrant activation of EGFR in NSCLC. First-generation EGFR tyrosine kinase inhibitors (TKIs) such as gefitinib and erlotinib have clinical benefits for EGFR-sensitive (L858R and Del19) NSCLC patients. However, after 10-12 months of treatment with these inhibitors, a secondary T790M mutation at the gatekeeper position in the kinase domain of EGFR was identified, which limited the clinical benefits. Second-generation EGFR irreversible inhibitors (afatinib and dacomitinib) were developed to overcome this T790M mutation. However, their lack of selectivity toward wild-type EGFR compromised their clinical benefits due to serious adverse events. Recently developed third-generation irreversible EGFR TKIs (osimertinib and lazertinib) are selective toward driving mutations and the T790M mutation, while sparing wild-type EGFR activity. The latest studies have concluded that their efficacy was also compromised by additional acquired mutations, including C797S, the key residue cysteine that forms covalent bonds with irreversible inhibitors. Because second- and third-generation EGFR TKIs are irreversible inhibitors, they are not effective against C797S containing EGFR triple mutations (Del19/T790M/C797S and L858R/T790M/C797S). Therefore, there is an urgent unmet medical need to develop next-generation EGFR TKIs that selectively inhibit EGFR triple mutations via a non-irreversible mechanism.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.790-798
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• 2008

Counter-rotating axial flow fan(CRF) consists of two counter-rotating rotors without stator blades. CRF shows the complex flow characteristics of the three-dimensional, viscous, and unsteady flow fields. For the understanding of the entire core flow in CRF, it is necessary to investigate the three-dimensional unsteady flow field between the rotors. This information is also essential to improve the aerodynamic characteristics and to reduce the aerodynamic noise level and vibration characteristics of the CRF. In this paper, experimental study on the three-dimensional unsteady flow of the CRF is performed at the design point(operating point). Flow fields in the CRF are measured at the cross-sectional planes of the upstream and downstream of each rotor using the $45^{\circ}$ inclined hot-wire. The phase-locked averaged hot-wire technique utilizes the inclined hot-wire, which rotates successively with 120 degree increments about its own axis. Three-dimensional unsteady flow characteristics such as tip vortex, secondary flow and tip leakage flow in the CRF are shown in the form of the axial, radial and tangential velocity vector plot and velocity contour. The phase-locked averaged velocity profiles of the CRF are analyzed by means of the stationary unsteady measurement technique. At the mean radius of the front rotor inlet and the outlet, the phase-locked averaged velocity profiles show more the periodical flow characteristics than those of the hub region. At the tip region of the CRF, the axial velocity is decreased due to the boundary layer effect of the fan casing and the tip vortex flow. The radial and the tangential velocity profiles show the most unstable and unsteady flow characteristics compared with other position of rotors. But, the phase-locked averaged velocity profiles of the downstream of the rear rotor show the aperiodic flow pattern due to the mixture of the front rotor wake period and the rear rotor rotational period.