• Journal of the Microelectronics and Packaging Society
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• v.28 no.3
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• pp.33-38
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• 2021

Recently, rollable and foldable displays are attracting great attention in the flexible display market due to their excellent form factor. To predict and prevent the mechanical failure of the display panels, it is essential to accurately understand the mechanical properties of brittle SiN_x thin films, which have been used as an insulating film in flexible displays. In this study, tensile properties of the ~130 nm- and ~320 nm-thick SiN_x thin films were successfully measured by coating a ~190 nm-thick organic nano-support-layer (PMMA, PS, P3HT) on the fragile SiN_x thin films and stretching the films as a bilayer state. Young's modulus values of the ~130 nm and ~320 nm SiN_x thin films fabricated through the controlled chamber pressure and deposition power (A: 1250 mTorr, 450 W/B: 1000 mTorr, 600 W/C: 750 mTorr, 700 W) were calculated as A: 76.6±3.5, B: 85.8±4.6, C: 117.4±6.5 GPa and A: 100.1±12.9, B: 117.9±9.7, C: 159.6 GPa, respectively. As a result, Young's modulus of ~320 nm SiN_x thin films fabricated through the same deposition condition increased compared to the ~130 nm SiN_x thin films. The tensile testing method using the organic nano-support-layer was effective in the precise measurement of the mechanical properties of the brittle thin films. The method developed in this study can contribute to the robust design of the rollable and foldable displays by enabling quantitative measurement of mechanical properties of fragile thin films for flexible displays.

• The Korean Journal of Archival Studies
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• no.12
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• pp.179-235
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• 2005

In this article, the task of evaluating the official documents that were created and issued by the Joseon Governor General office during the Japanese occupation period, with new perspectives based upon the Macro-Appraisal approaches developed by the Canadian scholars and personnel, will be attempted. Recently, the Canadian people and the authorities have been showing a tendency of evaluating the meaning and importance of a particular document with perspectives considering the historical situation and background conditions that gave birth to that document to be a more important factor, even than considering the quality and condition of that very document. Such approach requires the archivists to determine whether they should preserve a certain document or not based upon the meaning, functions and status of the entity that produced the document or the meaning of the documentation practice itself, rather than the actual document. With regard to the task of evaluating the official documents created and issued by the Joseon Governor General office and involved the city plans devised by the office back then, this author established total of 4 primary tasks that would prove crucial in the process of determining whether or not a particular theme, or event, or an ideology should be selected and documents involving those themes, events and ideologies should be preserved as important sources of information regarding the Korean history of the Japanese occupation period. Those four tasks are as follow: First, the archivists should study the current and past trends of historical researches. The archivists, who are usually not in the position of having comprehensive access to historical details, must consult the historians' studies and also the trends mirrored in such studies, in their efforts of selecting important historical events and themes. Second, the archivists should determine the level of importance of the officials who worked inside the Joseon Governor General office as they were the entities that produced the very documents. It is only natural to assume that the level of importance of a particular document must have been determined by the level of importance(in terms of official functions) of the official who authorized the document and ordered it to be released. Third, the archivists should be made well aware of the inner structure and official functions of the Joseon Governor General office, so that they can have more appropriate analyses. Fourth, in order to collect historically important documents that involved the Koreans(the Joseon people), the archivists should analyze not only the functions of the Joseon Governor General office in general but also certain areas of the Office's business in which the Japanese officials and the Koreans would have interacted with each other. The act of analyzing the documents only based upon their respective levels of apparent importance might lead the archivists to miss certain documents that reflected the Koreans' situation or were related to the general interest of the Korean people. This kind of evaluation should provide data that are required in appraising how well the Joseon Governor General office's function of devising city plans were documented back then, and how well they are preserved today, utilizing a comparative study involving the Joseon Governor General office's own evaluations of its documentations and the current status of documents that are in custody of the National Archive. The task would also end up proposing a specialized strategy of collecting data and documents that is direly needed in establishing a well-designed comprehensive archives. We should establish a plan regarding certain documents that were documented by the Joseon Governor General office but do not remain today, and devise a task model for the job of primary collecting that would take place in the future.

• Journal of The Korean Society of Grassland and Forage Science
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• v.39 no.2
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• pp.114-120
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• 2019

This study was carried out to explore the accuracy of near infrared spectroscopy(NIRS) for the prediction of moisture content and chemical parameters on winter annual forage crops. A population of 2454 winter annual forages representing a wide range in chemical parameters was used in this study. Samples of forage were scanned at 1nm intervals over the wavelength range 680-2500nm and the optical data was recorded as log 1/Reflectance(log 1/R), which scanned in intact fresh condition. The spectral data were regressed against a range of chemical parameters using partial least squares(PLS) multivariate analysis in conjunction with spectral math treatments to reduced the effect of extraneous noise. The optimum calibrations were selected based on the highest coefficients of determination in cross validation($R^2$) and the lowest standard error of cross-validation(SECV). The results of this study showed that NIRS calibration model to predict the moisture contents and chemical parameters had very high degree of accuracy except for barely. The $R^2$ and SECV for integrated winter annual forages calibration were 0.99(SECV 1.59%) for moisture, 0.89(SECV 1.15%) for acid detergent fiber, 0.86(SECV 1.43%) for neutral detergent fiber, 0.93(SECV 0.61%) for crude protein, 0.90(SECV 0.45%) for crude ash, and 0.82(SECV 3.76%) for relative feed value on a dry matter(%), respectively. Results of this experiment showed the possibility of NIRS method to predict the moisture and chemical composition of winter annual forage for routine analysis method to evaluate the feed value.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.19 no.1
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• pp.20-25
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• 2019

Very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency (OMIM#201475) is an autosomal recessively inherited metabolic disorder of mitochondrial long-chain fatty acid oxidation. The clinical features of VLCAD deficiency is classified by three clinical forms according to the severity. Here, we report a case of later-onset episodic myopathic form of VLCAD deficiency whose diagnosis was confirmed by plasma acylcarnitine analysis and" multigene panel multigene panel sequencing. A 34-year old female patient visited genetics clinic for genetic evaluation for history of recurrent myopathy with intermittent rhabdomyolysis. She suffered first episode of rhabdomyolysis with acute renal failure requiring hemodialysis at twelve years old. After then, she suffered several times of recurrent rhabdomyolysis provoked by prolonged exercise or fasting. Physical and neurologic exam was normal. Serum AST/ALT and creatinine kinase (CK) levels were mildly elevated. However, according to her previous medical records, her AST/ALT, CK were highly elevated when she had rhabdomyolysis. In suspicion of fatty acid oxidation disorder, multigene panel sequencing and plasma acylcarnitine analysis were performed in non-fasting, asymptomatic condition for the differential diagnosis. Plasma acylcarnitine analysis revealed elevated levels of C14:1 ($1.453{\mu}mol/L$; reference, 0.044-0.285), and C14:2 ($0.323{\mu}mol/L$; 0.032-0.301) and upper normal level of C14 ($0.841{\mu}mol/L$; 0.065 -0.920). Two heterozygous mutation in ACADVL were detected by multigene panel sequencing and confirmed by Sanger sequencing: c.[1202G>A(;) 1349G>A] (p.[(Ser 401Asn)(;)(Arg450His)]). Diagnosis of VLCAD deficiency was confirmed and frequent meal with low-fat diet was educated for preventing acute metabolic derangement. Fatty acid oxidation disorders have diagnostic challenges due to their intermittent clinical and laboratorial presentations, especially in milder late-onset forms. We suggest that multigene panel sequencing could be a useful diagnostic tool for the genetically and clinically heterogeneous fatty acid oxidation disorders.

• Journal of Climate Change Research
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• v.5 no.1
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• pp.1-12
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• 2014

With continued economic growth, Korea has seen an increase in the nighttime activities of its citizens as hours of activity have extended into night. There is an increasing trend in energy consumption related to citizens' nighttime activities. In order to analyze ideas for an efficient replacement of the power consumption of streetlights and for profit generation by applying grid-type solar systems, this study used an RETScreen model. Through energy analysis and cost analysis, the application benefit and viability of grid-type solar street light systems were analyzed. With analysis result of a total weekly power generation of 114 kWh via a grid-connected solar streetlight system, it was shown that the net present value of a grid-connected solar street light system is 155,362 KRW, which would mean a payback period of about 5.2 years, and as such, it was shown that profit could be generated after about 6 years. In addition, if the grid-connected solar power generation system proposed by this study is to be applied, it was shown that 401,935 KRW in profit could be generated after the 20-year useful life set for the solar system. In addition, the sensitivity analysis was performed taking into account the price fluctuations of SMP, maintenance. As a result, a payback period has increased by 1~2 years, and there were no significant differences. Because the most important factor that affect the economic analysis is the cost of supply certification of renewable energy, a stable sales and acquisition of this certification are very important. the Seoul-type Feed in Tariff(FIT) connected to other institutions will enable steady sales by confirming to purchase the certification for 12 years. Therefore, if those issues mentioned above are properly reflected, Central-grid PV system project will be able to perform well in the face of unfavorable condition of solar PV installation.

• Journal of the Korean Orthopaedic Association
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• v.53 no.6
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• pp.540-546
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• 2018

Purpose: The purpose of this study was to suggest a multimodal diagnostic approach to determine the cause of the disease in patients diagnosed with synovitis of the wrist and who underwent synovectomy. Materials and Methods: Twenty-nine patients, who underwent contrast magnetic resonance imaging (MRI) preoperatively and synovectomy from January 2000 to December 2013, were reviewed retrospectively. Among them, 17 patients underwent a $Tc^{99m}$ white blood cell (WBC) scan preoperatively. In patients who met the diagnostic criteria of rheumatoid arthritis (RA), the diagnosis was confirmed as RA if the MRI finding or histology was compatible with RA. If the MRI finding and histology were disparate, the final diagnosis was made based on the histologic finding. Results: Of the nine patients who met the diagnostic criteria of RA, seven patients were finally diagnosed as RA and two patients as tuberculous arthritis. Of the 20 patients who did not meet the diagnostic criteria of RA, the MRI findings and histology were consistent with the same disease in 12 patients. In the remaining eight patients, five were diagnosed with nonspecific chronic synovitis, one with RA, and two with tuberculous arthritis based on the clinical findings, MRI, and histology findings. Conclusion: MRI and a WBC scan are very useful imaging modalities for diagnosing the causative condition of the wrist synovitis. A histology evaluation after synovectomy can also be useful in cases with a difficult diagnosis or are refractory to medications.

• Korean Journal of Heritage: History & Science
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• v.50 no.4
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• pp.148-165
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• 2017

Mural paintings drawn inside ancient tombs are very sensitive to changes in the environment such as temperature and humidity, especially the finish layer of the tomb murals differ in preservability depending on the material properties and humidity conditions. In this study, I examined the mural painting of Songsan-ri Tomb No.6, where the finish layer was made of earth, and identified the physical changes that can occur due to drying, depending on the material properties of the finish layer. I found out through particle size analysis that the finish layer of the mural painting in Songsan-ri Tomb No.6 is about 85.0wt% below silt, about 14.0wt% clay therein, mostly composed of silt and below clay. I also found out through physical property evaluation that surface change rate of samples showed the largest change at 15.5% in reproduced finish layer sample made up of bentonite, followed by 7.8% of reproduced finish layer sample made up of celadon soil, 6.3% of reproduced finish layer sample made up of loess, 6.2% of reproduced finish layer sample composed of white clay and the same order of change in appearance was confirmed in each sample consisted of soil. In addition, it showed the same trend of surface change rate, and the bentonite condition showed the largest change, in the measurement of shrinkage rate and expansion rate. The experiment shows that the finish layer composed of soil is affected by cohesion among particles according to the content of fine parts and the relationship between the agglomeration due to the content of the differentiated part and the stress due to the expansibility depending on the kind of the clay mineral etc. Therefore, it can be concluded that the physical damage occurred in the mural painting finish layer of the Songsan-ri Tomb No.6 is related to the factors such as the material characteristics of the soil and the highly humid environmental change inside the tomb.

• Korean Journal of Ecology and Environment
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• v.52 no.2
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• pp.118-125
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• 2019

Swimming performance of fish is an important factor in the survival of fish. Also, swimming performance of fish is used in the form of habitat, or as a condition to consider when creating a fish ladder. However in Korea, researches in swimming performance of Korean freshwater fish were scarce and inadequate in some part, thus fish ladders were installed without considering their swimming performance. Therefore, in this study, we measured swimming performance of 4 Korean freshwater fish species to consider importance of swimming performance test. The fish used in this study were Carassius auratus, Zacco koreanus, Gnathopogon strigatus, Acheilognathus lanceolata intermedia species which was collected during October to November, 2018 at Geum River, and measurement for swimming speed of each fish was done by using $Loligo^{(R)}$ System, swim tunnel respirometer in January to February of 2019. The average value of the burst critical swimming speed ($U_{crit}$) for each species was $0.8{\pm}0.04m\;s^{-1}$ for C. auratus, $0.77{\pm}0.04m\;s^{-1}$ for Z. koreanus, $0.95{\pm}0.04m\;s^{-1}$ for G. strigatus, $0.73{\pm}0.03m\;s^{-1}$ for A. lanceolata intermedia and the average value of prolonged critical swimming speed was $0.54m\;s^{-1}$ for C. auratus, $0.67m\;s^{-1}$ for Z. koreanus, $0.7m\;s^{-1}$ for G. strigatus, $0.54m\;s^{-1}$ for A. lanceolata intermedia. Since the fish used in this experiment were collected from a small part of the water system in Korea and there were only 4 species, they were not enough to represent the species that inhabit the entire Korean water system. It will be necessary to continue evaluating the swimming performance of other freshwater species in Korea.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.2
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• pp.110-117
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• 2019

Purpose: This study was to evaluate the wear resistance of 3D printed, milled, and conventionally cured provisional resin materials. Materials and methods: Four types of resin materials made with different methods were examined: Stereolithography apparatus (SLA) 3D printed resin (S3P), digital light processing (DLP) 3D printed resin (D3P), milled resin (MIL), conventionally self-cured resin (CON). In the 3D printed resin specimens, the build orientation and layer thickness were set to $0^{\circ}$ and $100{\mu}m$, respectively. The specimens were tested in a 2-axis chewing simulator with the steatite as the antagonist under thermocycling condition (5 kg, 30,000 cycles, 0.8 Hz, $5^{\circ}C/55^{\circ}C$). Wear losses of the specimens were calculated using CAD software and scanning electron microscope (SEM) was used to investigate wear surface of the specimens. Statistical significance was determined using One-way ANOVA and Dunnett T3 analysis (${\alpha}=.05$). Results: Wear losses of the S3P, D3P, and MIL groups significantly smaller than those of the CON group (P < .05). There was no significant difference among S3P, D3P, and MIL group (P > .05). In the SEM observations, in the S3P and D3P groups, vertical cracks were observed in the sliding direction of the antagonist. In the MIL group, there was an overall uniform wear surface, whereas in the CON group, a distinct wear track and numerous bubbles were observed. Conclusion: Within the limits of this study, provisional resin materials made with 3D printing show adequate wear resistance for applications in dentistry.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.2
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• pp.181-189
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• 2021

Purpose: The purpose of this study is to investigate the stress response and sleep state of the new patients who visit the hospital for prosthodontic treatment due to tooth loss to make reference to further treatment direction. Materials and methods: Examinations, consultations, and surveys were conducted on 236 patients (94 males, 142 females, and 24-86 years old), who newly registered at the department of prosthodontics at Pusan national university hospital, for 2 years from 2018. The number of remaining teeth, edentulous arch, possibility of mastication, and future prosthetic treatment directions were recorded. The visual analogue scale (VAS), stress response inventory (SRI) and Insomnia severity index (ISI) were used as tools to measure patient's subjective discomfort, stress response, and sleep status. Results: Among the entire prosthodontic patient group, the average value of 'fatigue' was significantly higher among the 7 items of SRI, and the value of 'aggression' was significantly lower (P<.001). There are a significant difference between the edentulous and full dentition in the oral discomfort value measured by VAS (P=.004). In cases where less than 20 teeth remain, mastication is impossible, and patients who are planning treatment with removable prostheses, VAS value and 'depression' and 'fatigue' values in SRI were higher than those in the reverse case (P<.05). The patients showed severe level in VAS value have high value of 'tension', 'somatization', 'depression', 'fatigue'and 'frustration'in SRI than non-serious patients (P<.05). Clinical insomnia occurred in 11.4% of all patients, and women had significantly lower sleep quality than men (P=.044). Patients with insomnia showed significantly higher scores on the VAS value and all 7 SRI items than those of normal sleepers (P<.05). Conclusion: The new prosthetics had high 'fatigue' value among the 7 items of SRI. The oral condition, number of residual teeth and mastication function and clinical insomnia affected oral discomfort and the stress response.