• Structural Engineering and Mechanics
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• v.90 no.3
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• pp.219-232
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• 2024

In current study, for the first time, Nonlinear Bending of a skew microplate made of a laminated composite strengthened with graphene nanosheets is investigated. A mixture of mechanical and thermal stresses is applied to the plate, and the reaction is analyzed using the First Shear Deformation Theory (FSDT). Since different percentages of graphene sheets are included in the multilayer structure of the composite, the characteristics of the composite are functionally graded throughout its thickness. Halpin-Tsai models are used to characterize mechanical qualities, whereas Schapery models are used to characterize thermal properties. The microplate's non-linear strain is first calculated by calculating the plate shear deformation and using the Green-Lagrange tensor and von Karman assumptions. Then the elements of the Couple and Cauchy stress tensors using the Modified Coupled Stress Theory (MCST) are derived. Next, using the Hamilton Principle, the microplate's governing equations and associated boundary conditions are calculated. The nonlinear differential equations are linearized by utilizing auxiliary variables in the nonlinear solution by applying the Frechet approach. The linearized equations are rectified via an iterative loop to precisely solve the problem. For this, the Differential Quadrature Method (DQM) is utilized, and the outcomes are shown for the basic support boundary condition. To ascertain the maximum values of microplate deflection for a range of circumstances-such as skew angles, volume fractions, configurations, temperatures, and length scales-a parametric analysis is carried out. To shed light on how the microplate behaves in these various circumstances, the resulting results are analyzed.

• Publications of The Korean Astronomical Society
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• v.39 no.2
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• pp.39-51
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• 2024

Since the division of the Korean Peninsula in 1948, South and North Korea have independently developed their astronomical almanacs: Ryeokseo at the Korea Astronomy and Space Science Institute in South Korea and Cheonmunryeok at the Pyongyang Astronomical Observatory in North Korea. This study compares Ryeokseo and Cheonmunryeok for the year 2015, focusing on publication systems, content, terminology, and differences in data calculation methods. Additionally, it examines the calendars of South and North Korea from 2018 to 2023, analyzing similarities and differences in the representation of calendrical dates, public holidays, and other related aspects. The findings reveal that while the structure and content of the astronomical almanacs are similar in both countries, notable variances exist in the versions of ephemerides, time scales, and calculation precision. Consequently, identical data points are often recorded with slightly different values in each country's almanacs. Furthermore, approximately 28% of the terms used in North Korea's astronomical almanac are either not utilized in South Korea or have different definitions. Regarding calendar systems, those of South and North Korea are largely similar, resulting in no significant discrepancies in dates. However, there are notable differences in the observance of public holidays. While traditional holidays are common to both, most holidays are distinctively celebrated. Notably, North Korea does not observe religious holidays, and many of its holidays are associated with the regime.

• Monthly Notices of the Royal Astronomical Society
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• v.496 no.4
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• pp.4787-4821
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• 2020

The merging rate of cosmic structures is computed, relying on the ansatz that they can be predicted in the initial linear density field from the coalescence of critical points with increasing smoothing scale, used here as a proxy for cosmic time. Beyond the mergers of peaks with saddle points (a proxy for halo mergers), we consider the coalescence and nucleation of all sets of critical points, including wall-saddle to filament-saddle and wall-saddle to minima (a proxy for filament and void mergers, respectively), as they impact the geometry of galactic infall, and in particular filament disconnection. Analytical predictions of the one-point statistics are validated against multiscale measurements in 2D and 3D realizations of Gaussian random fields (the corresponding code being available upon request) and compared qualitatively to cosmological N-body simulations at early times (z ≥ 10) and large scales (≥5 Mpc h^-1). The rate of filament coalescence is compared to the merger rate of haloes and the two-point clustering of these events is computed, along with their cross-correlations with critical points. These correlations are qualitatively consistent with the preservation of the connectivity of dark matter haloes, and the impact of the large-scale structures on assembly bias. The destruction rate of haloes and voids as a function of mass and redshift is quantified down to z = 0 for a Lambda cold dark matter cosmology. The one-point statistics in higher dimensions are also presented, together with consistency relations between critical point and critical event counts.

• Journal of Climate Change Research
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• v.34 no.16
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• pp.6841-6853
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• 2021

The leading modes of the North Pacific jet (NPJ) variability include intensity changes and meridional shifts in jet position on low-frequency time scales. These leading modes of NPJ variability are closely associated with weather and climate conditions spanning from Asia to the United States. In this study, we investigated changes in the NPJ's role as a conduit for U.S. surface air temperature (SAT) anomalies during the boreal winter across the late 1990s. We found that the leading mode of NPJ variability changed from the NPJ intensity changes to meridional shifts in NPJ position across the late 1990s. It leads to the change in the role of the NPJ as a conduit for U.S. SAT anomalies. Before the late 1990s, the variability of NPJ intensity significantly impacted western U.S. SAT anomalies related to the anomalous surface cyclonic circulation over the North Pacific. After the late 1990s, however, the variability of the NPJ's meridional shift significantly influenced the eastern U.S. SAT anomalies in association with the anomalous surface cyclonic circulation over the northern North Pacific. Further analysis and model experiments revealed that the western to central North Pacific Ocean has been warming since the late 1990s and modulates atmospheric baroclinicity. This phenomenon mainly leads to a northward NPJ shift and implies that the eddy-driven mechanism on the NPJ's formation, which acts to enhance the meridional variability of NPJ position, becomes dominant. We conclude that this northward shift of NPJ could have contributed to enhancing the NPJ's meridional shift variability, significantly influencing the eastern U.S. SAT anomalies since the late 1990s.

• Clinical and Experimental Pediatrics
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• v.50 no.11
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• pp.1061-1066
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• 2007

Purpose : Early identification of developmental disabilities allows intervention at the earliest possible point to improve the developmental potential. The Ages and Stages Questionnaire (ASQ), a parent- completed questionnaire, can be used as a substitute for formal screening tests. The purpose of this study was to evaluate the validity of the Korean version of the ASQ (K-ASQ) as a screening tool for detecting developmental delay of young Korean children in the setting of a busy pediatric outpatient clinic. Methods : Parents completed the K-ASQ in the waiting room of the pediatric outpatient clinic of St. Mary's Hospital, Catholic University Medical College. Out of 150 completed the ASQ, 67 who were born term and had no previous diagnosis of developmental delay, congenital anomalies, or neurological abnormalities were enrolled. The cut-off values of less than 2 standard deviations (SD) below the mean for the ASQ were used to define a "fail", and children who failed in one or more domains tested were classified as "screen-positive". Diagnosis of developmental delay was made when the developmental indices fell below -1 SD of the Bayley Scales of Infant Development-II. Results : (1) The mean age of children was $16.4{\pm}7.4$ months. Ten children (14.9%) were small-for- gestational age infants. The mean birth weight and gestational age were $3.1{\pm}0.6kg$ and $38.8{\pm}1.4$ weeks. Nine children (13.4%) were twins and 33 (49.0%) were male. The mean maternal education in years was $13.6{\pm}2.4$, and 31.3% had full-time jobs. The time for completing the ASQ was $10.2{\pm}3.0$ minutes. (2) Seventeen children (25.4%) were classified as screen-positive, four of them were delayed in development. Among eight children diagnosed with developmental delay, four were screen-positive and the other four were screen-negative by the ASQ. (3) The test characteristics of the ASQ were as follows: sensitivity (50.0%); specificity (78.0%); positive predictive value (23.5%); negative predictive value (92.0%). Conclusion : The high negative predictive value of the K-ASQ supports its use as a screening tool for developmental delay in the setting of a pediatric outpatient clinic.

• Sleep Medicine and Psychophysiology
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• v.24 no.2
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• pp.86-96
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• 2017

Objectives: This study aimed to analyze causality among sleep apnea, depression and cognitive function in patients with obstructive sleep apnea. Methods: We reviewed the medical records of 105 patients with sleep apnea and snoring who underwent overnight polysomnography (PSG). We analyzed various biological data, sleep variables (sleep duration and percentage) and respiratory variables [arousal index (AI), periodic leg movement index (PLM index), snoring Index (SI), mean SpO2, minimum SpO2, apnea-hypopnea index (AHI), and respiratory disturbance index (RDI)]. We also analyzed various data by sleep, cognition, and mood related scales: Pittsburgh sleep quality index (PSQI), Epworth sleepiness scale (ESS), snoring index by scale (SIS), Montreal Cognitive Assessment-Korean (Moca-K), Mini-mental State Examination-Korean (MMSE-K), clinical dementia rating (CDR), and Beck Depression Inventory (BDI). We analyzed causation among sleep, and respiratory, mood, and cognition related scales in obstructive sleep apnea patients. We analyzed the mediating effects of depression on sleep apnea patient cognition. Results: As Duration N1 increased and Total sleep time (TST) decreased, MOCA-K showed negative causality (p < 0.01). As BDI and supine RDI increased, causality was negatively related to MOCA-K (p < 0.01). As PSQI (p < 0.001) and SIS (p < 0.01) increased and as MMSE-K (p < 0.01) decreased, causality was positively related to BDI. BDI was found to mediate the effect of age on MOCA-K in patients with obstructive sleep apnea. Conclusion: Duration N1, total sleep time, BDI, and supine RDI were associated with cognitive function in obstructive sleep apnea patients. Depression measured by BDI partially mediated cognitive decline in obstructive sleep apnea patients.

• Journal of the Korean Arthroscopy Society
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• v.15 no.1
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• pp.1-6
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• 2011

Purpose: The purpose of this prospective study is to compare the results of arthroscopic reconstruction of ACL using autologous hamstring tendon (Group 1) and autologous bone patella tendon bone (Group 2). Materials and Methods: From Jan. 2004 to Dec. 2007, fifty patients were analyzed in this study. A single surgeon performed the ACL reconstruction with autologous hamstring tendon (25 patients) and autologous bone patella tendon bone (25 patients) alternatively each other. The mean follow up period of two groups was 38 months (range 25~58 months). We evaluated the result of Lachman test, Pivot shift test as a physical examination and Lysholm score, Tagner activity scale as patients' satisfaction and functional status and Telometer for anterior instability of each groups at the time of final follow up. Results: In final results, negative or mild positive findings on Lachman test were 24 out of 25 cases (equally) in each groups.) Twenty two cases in the Group 1 and 21 cases in the Group 2 were negative on Pivot shift test. Lysholm scores mark 94.6 points in group 1 and 92.3 points in group 2 at the final follow up and Tegner activity scales mark 8.5 points (Group 1) and 8.1 points (Group 2) at the time of last follow up and there were no differences between the two groups statistically. The numbers of patients who have less than 5 mm of anterior translation of tibia under telometer at 20 degrees of knee flexion are 24 cases in group 1 and 23 cases in group 2. Conclusion: The overall improvements of clinical scores (Lysholm scores and Tegner Activity scales) of the group 1 were a little bit superior to those of the group 2, but there were no significant statistical difference between two groups.

• Journal of Gifted/Talented Education
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• v.21 no.1
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• pp.57-81
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• 2011

The purpose of this study was to explore the quality of life of musically talented students as measured by their external experiences (e.g., activities, companions) and internal experiences (e.g., flow, emotion). The participants in this study were 33 musically talented students (10 males, 23 females) aged 13 to 19. Study data were collected for 7 consecutive days using the Experience Sampling Method (ESM), which employs a cellular-phone as a signaling device. The results were as follows: First, in response to the 1625 random signals, musically talented students reported that 40.9% of their time was spent on productive activities. An additional 33.4% of time was used for maintenance activities and the rest of their time was spent on leisure/social activities. Also, musically talented students reported that 48.5% of their time was spent alone. When they were alone, they spent a lot of time engaging in productive activities (44.3%). Second, in order to measure the flow of their life, two methods were used. One used a 4-channel flow model (i.e. apathy, boredom, flow, anxiety) and the other used 8 dimensions and conditions of the flow experience (i.e. concentration, self-consciousness disappears, action and awareness merge, distorted sense of time, freedom from worry about failure, clear goals, immediate feedback, balance between challenges and skills). According to the former, when engaged in music-related activities, musically talented students usually reported flow (54.0%), while they felt apathy (41.3%) for daily routines activities. According to the latter method, musically talented students experienced flow for most productive activities, while they experienced flow least for maintenance activities. Emotional variables of ESF are comprised of 10 semantic scales (i.e. happy-sad, strong-weak, active-passive, sociablelonely, proud-ashamed, involved-detached, excited-bored, clear-confused, relaxed-worried, cooperative-competitive). Musically talented students reported experiencing the most positive emotion for social activities and experiencing the most negative emotion for maintenance activities. Results of this study assert that musically talented students had to trade off immediate enjoyment for developing their special gifts. They could not afford as much time for socializing with friends, and they had to spend more time alone compared to their peers without such gifts. Consequently, they were found to deprive themselves of the spontaneous good times that teenagers usually thrive on. They were helped in this respect by their autotelic personality traits, especially their strong need for achievement and endurance. The downside, however, is that the moment-to-moment quality of their moods suffered. The argument concerning musically talented students applies for all adolescents. The choices that talented students must make between immediate gratification and long-term development, and between solitude and companionship, are the same choices every young person must make, regardless of her or his level of talent. All of us have gifts that are potentially useful and worthy of being appreciated. But to develop these latent talents we must cultivate them, and this takes time and the investment of mental energy. The lifestyle that musically talented students develop can show us some of the choices all of us must make in order to cultivate our gifts.

• Journal of Food Hygiene and Safety
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• v.15 no.4
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• pp.304-314
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• 2000

Following the recent policy, enlargement of foodservice and contracted management systems of high school foodservices have been accelerated, and the scales of foodservices have been gradually increased. A sudden growth of domestic foodservice companies have remarkably disparated. Yet compared to that of the foodseuice control in advanced countries, domestic foodservice control has a lot more to learn. Due to the characteristics of foodservice establishment serving many people at a time, there is always a high potential of food bone outbreak. The purpose of this study was to evluate hazard factors in the steps of production, holding and assembly and service of fried curry hair-tail, cold seaweed and cucumber, fried pork cutlet, that were served by contracted management in high school foodservice centre, then to suggest method of control with the Hazard Analysis Critical Control Point(HACCP) program. Also we suggested the possibility that the contracted management of foodservice system can be established and utilized to identify the variation of holding temperature among floods up to 6 hours after cooking. The results are as follows; The hazard factors in food product had come from the temperature, time, pH, Aw, equipment and utensils. The critical control point(CCP) of each food product; curry hair-tail, cold seaweed and cucumber and pork cutlet was cooked and held before serving, prepared and held before serving, cooked and held before serving, and prepared, cooked and held before serving, respectively.

• ALGAE
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• v.28 no.3
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• pp.213-231
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• 2013

Amphidinium massartii Biecheler is an epiphytic and toxic dinoflagellate. Prior to the present study, A. massartii has been reported in the waters off the Mediterranean, Australian, USA, and Canadian coasts. We isolated Amphidinium cells from the coastal waters of Jeju Island, Korea and their morphology and rDNA sequences indicated that they were A. massartii. Herein, we report for the first time the occurrence of A. massartii in the waters of the temperate region in the northwestern Pacific Ocean. The large subunit (LSU) rDNA sequences of the Korean strains were 0.7% different from those of an Australian strain of A. massartii CS-259, the closest species, but were 4.1-5.8% different from those of the other Australian strains and the USA strains of A. massartii and from those of Amphidinium sp. HG115 that was isolated from subtropical Okinawan waters. In phylogenetic trees based on LSU, internal transcribed spacer, small subunit rDNA, and cytochrome b sequences, the Korean strains belonged to the A. massartii clade, which was clearly divergent from the A. carterae clade. The morphology of the Korean A. massartii strains was similar to that of the originally described French strain and recently described Australian strain. However, we report for the first time here that scales were observed on the surface of the flagella. In conclusion, the Korean A. massartii strains have unique rDNA sequences, even though they have a very similar morphology to that of previously reported strains. This report extends the known range of this dinoflagellate to the temperate waters of the northwestern Pacific Ocean.