• Journal of Mechanical Science and Technology
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• v.18 no.7
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• pp.1246-1257
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• 2004

The objective of this paper is to characterize dynamic pressure traces measured at self-excited combustion instabilities occurring in two combustion systems of different hardware. One system is a model lean premixed gas turbine combustor and the other a fullscale bipropellant liquid rocket thrust chamber. It is commonly observed in both systems that low frequency waves at around 300㎐ are first excited at the onset of combustion instabilities and after a short duration, the instability mode becomes coupled to the resonant acoustic modes of the combustion chamber, the first longitudinal mode for the lean premixed combustor and the first tangential mode for the rocket thrust chamber. Low frequency waves seem to get excited at first since flame shows the higher heat release response on the lower frequency perturbations with the smaller phase differences between heat release and pressure fluctuations. Nonlinear time series analysis of pressure traces reveals that even stable combustion might have chaotic behavior with the positive maximum Lyapunov exponent. Also, pressure fluctuations under combustion instabilities reach a limit cycle or quasi-periodic oscillations at the very similar run conditions, which manifest that a self-excited high frequency instability has strong nonlinear characteristics.

• Experimental and Molecular Medicine
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• v.50 no.11
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• pp.3.1-3.11
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• 2018

This study aimed to verify the effects of estrogen on the onset and development of adolescent idiopathic scoliosis and the mechanisms associated with these effects by constructing a pubescent bipedal rat model. Experiments were conducted to investigate whether scoliosis progression was prevented by a Triptorelin treatment. One hundred twenty bipedal rats were divided into female, OVX (ovariectomy), OVX + E2, Triptorelin, sham, and male groups. According to a spinal radiographic analysis, the scoliosis rates and curve severity of the female and OVX + E2 groups were higher than those in the OVX, Triptorelin, and male groups. The measurements obtained from the sagittal plane of thoracic vertebrae CT confirmed a relatively slower growth of the anterior elements and a faster growth of the posterior elements between T11 and T13 in the female and OVX + E2 groups than in the OVX and Triptorelin groups. Histomorphometry and immunohistochemistry revealed a significantly longer hypertrophic zone of the vertebral cartilage growth plates that expressed more type X collagen and less type II collagen in the OVX and Triptorelin groups than in the female and OVX + E2 groups. Ki67 immunostaining confirmed an increase in the proliferation of vertebral growth plate chondrocytes in the OVX group compared with the female and OVX + E2 groups. In conclusion, estrogen obviously increased the incidence of scoliosis and curve severity in pubescent bipedal rats. The underlying mechanism may be a loss of coupling of the endochondral ossification between the anterior and posterior columns. Triptorelin decreased the incidence of scoliosis and curve magnitudes in bipedal female rats.

• Korean Journal of Child Studies
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• v.38 no.3
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• pp.75-90
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• 2017

Objective: This study aimed to identify children's cognitive processing and performance characteristics while multiple task performance. It confirmed whether their multiple task performance and psychological refractory period (PRP) varied by task condition (stimulus onset asynchrony [SOA] and task difficulty) and stimulus modality. Methods: Seventy 5-year-olds were recruited. Multi-task tools were developed using the E-prime software. The children were required to respond to two stimuli (visual or auditory) presented with microscopic time difference and their response times (RTs) were recorded. Results: As the SOA increased, the RTs in the first task increased, while the RTs in the second task and PRP decreased. The RTs of the first and second tasks, and the PRP for difficult tasks, were significantly longer than those for easy tasks were. Additionally, there was an interaction effect between the SOA and task difficulty. Although there was no main effect of stimulus modality, task difficulty moderated the modality effect. In the high difficulty condition, the RTs of the first and second tasks and PRP for the visual-visual task were significantly longer than those for auditory-auditory task were. Conclusion: These results inform theoretical discussions on children's multi-task mechanism, and the loss of multiple task performance. Additionally, they provide practical implications and information on the composition of multi-tasks suitable for children in educational environments.

• Journal of Acupuncture Research
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• v.37 no.3
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• pp.161-166
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• 2020

Background: The purpose of this study was to investigate the characteristics and direction of treatment for peripheral facial palsy (PFP) based on medical collaboration between Western and Korean medicine departments. Methods: There were 195 outpatients with PFP identified retrospectively by examining electronic medical records. These patients were treated with Korean and Western medicine from January 1^st, 2018 to December 31^st, 2018 at the Kyung Hee University hospital. Records were analyzed according to the patients' demographic characteristics and clinical features of the collaborative combined treatment. Results: According to the collaborative treatment pathway, the number of patients consulted from Western medicine departments was more than consulted from Korean department for the first time. The time taken by the Western medicine departments to consult with the patients at the Korean center for the first time was 14.9 days from the onset of symptoms. Acupuncture was the most frequently used Korean medicine treatment. The total treatment period for Korean medicine sessions and intervals were 91.9 days, 23 times and 3.6 days, respectively. When the Korean medicine center consulted with Western medicine departments, the time taken until the first consultation was 8.5 days from the onset of symptoms. Medication was the most used treatment, prescribed after 3.1 days. The most frequently used clinical test was an electromyogram, and this was performed after 20.5 days. The total treatment period, sessions and intervals were 21.2 days, 2.8 times and 5 days, respectively. Conclusion: The clinical status of collaborative treatment for PFP was determined including the timing and interval of consultation according to treatments.

• Childhood Kidney Diseases
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• v.21 no.2
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• pp.128-135
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• 2017

Purpose: Extended-spectrum ${\beta}$-lactamase-producing bacteria-induced urinary tract infections are increasing and require more potent antibiotics such as carbapenems. We evaluated the clinical significance of extended-spectrum ${\beta}$-lactamase -urinary tract infection in children younger than 5 years to select proper antibiotics and determine prognostic factors. Differences were compared between age groups. Methods: We retrospectively studied 288 patients with their first febrile urinary tract infection when they were younger than 5 years. Patients were divided into extended-spectrum ${\beta}$-lactamase-positive and extended-spectrum ${\beta}$-lactamasenegative urinary tract infection groups. Clinical characteristics and outcomes were compared between the groups; an infant group was separately analyzed (onset age younger than 3 months). Results: Extended-spectrum ${\beta}$-lactamase urinary tract infection occurred in 11 % patients who had more frequent previous hospitalization (P=0.02) and higher recurrence rate (P=0.045). During the antimicrobial susceptibility test, the extended-spectrum ${\beta}$-lactamase-positive urinary tract infection group showed resistance to third-generation cephalosporins; however, 98% patients responded clinically. In the infant group, extended-spectrum ${\beta}$-lactamase-positive urinary tract infection occurred in 13% patients and was associated with a longer pre-onset hospitalization history (P=0.002), higher C-reactive protein level (P=0.04), and higher recurrence rate (P=0.02) than that in the older group. Conclusion: Extended-spectrum ${\beta}$-lactamase urinary tract infection requires more attention because of its higher recurrence rate. The antimicrobial susceptibility test demonstrated resistance to third-generation cephalosporins, but they can be used as first-line empirical antibiotics because of their high clinical response rate. Aminoglycosides can be second-line antibiotics before starting carbapenems when third-generation cephalosporins do not show bactericidal effects for extended-spectrum ${\beta}$-lactamase urinary tract infection.

• Development and Reproduction
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• v.18 no.4
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• pp.267-274
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• 2014

The immune system in teleost fish is not completely developed during embryonic and larval stages, therefore effective innate mechanisms is very important for survival in such an environment. However, the knowledge of the development of immune system assumed to be restricted. In many species, lysozymes have been considered as important genes of the first line immune defense. The early detection of lysozyme mRNA in previous reports, led to the investigation of its presence in oocytes. As a result, c-type lysozyme mRNA transcripts were detected in unfertilized oocytes indicating maternal transfer. Therefore, we investigated the expression patterns of lysozymes in flounder, including the matured oocyte. In our results, c-type lysozyme mRNA was first detected in unfertilized oocyte stage, observed the significantly decreased until hatching stage, and was significantly increased after hatching stage. On the other hand, g-type lysozyme mRNA transcripts were first detected at late neurula stage, and the mRNA level was significantly increased after 20 dph. It may be suggest that maternally supplied mRNAs are selectively degraded prior to the activation of embryonic transcription. This study will be help in understanding the maturation and onset of humoral immunity during development of olive flounder immune system.

• Clinical and Experimental Pediatrics
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• v.46 no.9
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• pp.889-892
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• 2003

Purpose : This study aimed to evaluate risk factors of the first year relapse in children with nephrotic syndrome(NS) without the need for biopsy. Methods : We reviewed, retrospectively, 78 children diagnosed with steroid responsive nephrotic syndrome between July 1997 and June 2002. Median years to follow up were 4.4 years(range : 1-5 years). We divided the patients into two groups(group I : primary responders with no relapse or with only two relapses in the first year after initial response; group II : initial steroid responders with three or more relapses within the first year). We retrospectively reviewed and compared variables - sex, onset age, serum albumin, serum cholesterol, 24 hours urinary protein, creatinine clearance(Ccr), presence of hematuria and hypertension(HTN), and days from initial attack to remission. Results : Of 78 patients(male : 61(78.2%), female : 17(21.8%), age range 1.1 years to 14 years, median $5.1{\pm}3.0years$), 47(60.3%) were in group I and 31(39.7%) were in group II. There were no statistically significant differences in sex, serum albumin, serum cholesterol, 24 hours urinary protein, Ccr, presence of hematuria or HTN. The median age of onset showed no statistical difference between the two groups. However, if the patients are dividing into two groups according to the age of onset of three-years, patients theree yrs old or less fit into group II, as opposed to patients older than three yrs in age(63.2% vs. 32.2%, P<0.05). The days from initial attack to remission was longer in group II($12.9{\pm}0.5$ vs. $16.2{\pm}1.1$, P<0.05). Conclusion : We may conclude that the age of onset of three yrs old or less, and the longer time remission to initial steroid therapy, are risk factors of the first year relapse.

• Clinical and Experimental Pediatrics
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• v.49 no.6
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• pp.623-629
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• 2006

Purpose : The mortality rate of neonatal sepsis has been decreased, however, the incidence has not significantly decreased because of increased invasive procedures. This study was designed to make guidelines for choosing antibiotics by analyzing the causative microorganisms and their antibiotics sensitivity test according to the onset of neonatal sepsis. Methods : One hundred seven cases of culture proven sepsis in 89 patients admitted to the NICU of Chonnam University Hospital from Jan. 2000 to Dec. 2004, were enrolled. By reviewing the medical records, clinical data, laboratory findings, causative organisms and their antibiotics sensitivity, and mortality were analyzed. Results : The incidence of neonatal sepsis was 1.7 percent and more prevalent in premature and low birth weight infants. 85.4 percent of neonatal sepsis was late onset. Almost all microorganisms(92.9 percent) were gram-positive in early onset, however, two thirds were gram-positive and one third were gram-negative and Candida in late onset. Gram-negative organisms and Candida were more prevalent in patients who had central line. Gram-positive organisms were sensitive to vancomycin, teicoplanin, and gram-negative were sensitive to imipenem, and cefotaxime. Conclusion : Neonatal sepsis was more prevalent in premature and low birth weight infants. More than 90 percent were gram-positive in early onset, however, one third was gram-negative and Candida in late onset. The first choice of antibiotics were a combination of third generation cephalosporin and clindamycin in early onset, and third generation cephalosporin and glycopeptide in late onset. If there is no response to antibiotics treatment, the use of antifungal agents should be considered.

• Pediatric Infection and Vaccine
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• v.3 no.2
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• pp.168-174
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• 1996

Purpose : Aseptic meningitis is relatively frequent in children and caused mostly by enterovirus. The aim of the present study was to determine the effect of early diagnosis (spinal tapping) on symptom duration of childhood aseptic meningitis. Methods : One hundred fifty-three children who were hospitalized due to aseptic menigitis in the Department of Pediatrics St. Benedict Hospital from July 1996 through October 1996 were included in this study. Patients were divided to two groups according to the duration from first symptom onset to diagnosis. Early diagnosis group is diagnosed within 3 days from first symptom onset. Later diagnosis group is diagnosed after 4 days from first symptom onset. Results : 1) The average age of these patients was 4.3 years old in early diagnosis group and 4.1 years old in later diagnosis group. The sex ratio(male: female) was 2.04:1 in early diagnosis group and 2.5:1 in later diagnosis group. 2) The mean duration of diagnosis of this study was 2.04 day in early diagnosis group and 5.12 day in later diagnosis group. 3) The percentage of symptom and sign of the early diagnosis group were fever(100%), headache(88.4%), vomiting(86.9%), abdominal pain(39%), neck stiffness(36.2%), skin rash(18.8%), diarrhea(16.9%) and that of later diagosis group were fever(100%), headache(83.3), vomiting(80.9%), abdominal pain(47.6%), neck stiffness(41.6%), skin rash(29.7%), diarrhea(16.6%). 4) Initial CSF findings revealed leukocyte $146.8{\pm}386.3/mm^3$ with PMNL 38%, protein 32.47mg/dl, sugar 66.23mg/dl in early diagnosis group and leukocyte $458.1{\pm}663.2/mm^3$, protein 31.22mg/dl, sugar 64.21 mg/dl in later diagnosis group. 5) There was no statistically significant differance in the peripheral blood findings between early diagnosis group and later diagnosis group. 6) The duration of disappearance of symptom after spinal tap were 2.3 days in early diagnosis group and 2.24 days in later diagnosis group. Total symptom duration was 4.34 days in early diagnosis group and 7.36 days in later diagnosis group. Conclusions : Our results demonstrate that early diagnosis(early spinal tap) shortened duration of clinical symptoms.

• Pediatric Infection and Vaccine
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• v.22 no.1
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• pp.1-6
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• 2015

Purpose: This study investigated an outbreak of mumps affecting students in a high school (S high school) in Seoul, with an evaluation of the diagnostic utility of the mumps polymerase chain reaction (PCR) assay. Methods: S high school students that presented to health care providers with mumps symptoms between April 2013 and July 2013 were surveyed for the monthly distribution of symptom onset and their grade level. Mumps PCR assays were performed using buccal swabs from some of these students. Results: During the survey period, 77 students presented with suspected cases of mumps. The monthly distribution of symptom onset was as follows: one in April, 17 in May, 54 in June, and five in July. With regard to grade level, 26 students were in their first year, 28 were in their second year, and 23 were in their third year. Of the 18 students tested with PCR assays, five had positive results. Samples were collected within 3 days of symptom onset in 15 of the 18 students, and positive PCR results were obtained in five of these 15 students. The PCR results of the remaining three students from whom samples were collected more than 3 days after the onset of symptoms were negative (P=0.24). Conclusions: We evaluated the epidemiological aspects of an outbreak of mumps in a high school. Mumps PCR might be epidemiologically useful if performed within 3 days of the onset of symptoms in suspected cases.