• Korean Journal of Audiology
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• v.24 no.1
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• pp.10-16
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• 2020

Background and Objectives:The blockage of adenosine receptors by caffeine changes the levels of neurotransmitters. These receptors are present in all parts of the body, including the auditory and vestibular systems. This study aimed to evaluate the effect of caffeine on evoked potentials using auditory brainstem responses (ABRs) and cervical vestibular-evoked myogenic potentials (cVEMPs) in a double-blind placebo-controlled study. Subjects and Methods: Forty individuals (20 females and 20 males; aged 18-25 years) were randomly assigned to two groups: the test group (consuming 3 mg/kg pure caffeine powder with little sugar and dry milk in 100 mL of water), and the placebo group (consuming only sugar and dry milk in 100 mL water as placebo). The cVEMPs and ABRs were recorded before and after caffeine or placebo intake. Results: A significant difference was observed in the absolute latencies of I and III (p<0.010), and V (p<0.001) and in the inter-peak latencies of III-V and I-V (p<0.001) of ABRs wave. In contrast, no significant difference was found in cVEMP parameters (P13 and N23 latency, threshold, P13-N23 amplitude, and amplitude ratio). The mean amplitudes of P13-N23 showed an increase after caffeine ingestion. However, this was not significant compared with the placebo group (p>0.050). Conclusions: It seems that the extent of caffeine's effects varies for differently evoked potentials. Latency reduction in ABRs indicates that caffeine improves transmission in the central brain auditory pathways. However, different effects of caffeine on auditory- and vestibular-evoked potentials could be attributed to the differences in sensitivities of the ABR and cVEMP tests.

• Korean Journal of Clinical Laboratory Science
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• v.54 no.3
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• pp.173-178
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• 2022

The majority of the children experience milder coronavirus disease 2019 (COVID-19) symptoms. Children represent a significant source of community transmission. Children under 18 years of age account for an estimated 4.8% of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections globally. However, no conclusive statements pertaining to the multi-fold aspects of the virus in children could be drawn due to the lower prevalence of pediatric cases. The present study was conducted to identify the indirect impact of SARS-CoV-2 infections on developing herd immunity among children in the age group 3 to 18 years by investigating their antibody levels. In the study, 240 children aged 3~18 years were recruited by the Department of Pediatrics, Government Medical College and Hospital, Amritsar, India, and quantification of the antibodies was performed at the Viral Research and Diagnostic Laboratory (VRDL), Government Medical College (GMC), Amritsar, India. Out of the 240 serum samples, 197 (82.08%) showed seropositivity, while 43 (17.92%) were seronegative. When stratified, it was observed that in the age group 3~6 years, 22.33% of children were found to have anti-SARS-CoV-2 antibodies while in the age groups 7~10 years, 11~14 years, and 15~18 years, respectively, 37.06%, 30.46%, and 10.15% were seropositive. Although there was seroconversion among children which was useful for predicting the next wave, no differences in seropositivity were observed between adults and children.

• Journal of Preventive Medicine and Public Health
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• v.56 no.3
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• pp.221-230
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• 2023

Objectives: The second wave of coronavirus disease 2019 (COVID-19) cases in Indonesia, during which the Delta variant predominated, took place after a vaccination program had been initiated in the country. This study was conducted to assess the impact of COVID-19 vaccination on unfavorable clinical outcomes including hospitalization, severe COVID-19, intensive care unit (ICU) admission, and death using a real-world model. Methods: This single-center retrospective cohort study involved patients with COVID-19 aged ≥18 years who presented to the COVID-19 emergency room at a secondary referral teaching hospital between June 1, 2021 and August 31, 2021. We used a binary logistic regression model to assess the effect of COVID-19 vaccination on unfavorable clinical outcomes, with age, sex, and comorbidities as confounding variables. Results: A total of 716 patients were included, 32.1% of whom were vaccinated. The elderly participants (≥65 years) had the lowest vaccine coverage among age groups. Vaccination had an effectiveness of 50% (95% confidence interval [CI], 25 to 66) for preventing hospitalization, 97% (95% CI, 77 to 99) for preventing severe COVID-19, 95% (95% CI, 56 to 99) for preventing ICU admission, and 90% (95% CI, 22 to 99) for preventing death. Interestingly, patients with type 2 diabetes had a 2-fold to 4-fold elevated risk of unfavorable outcomes. Conclusions: Among adults, COVID-19 vaccination has a moderate preventive impact on hospitalization but a high preventive impact on severe COVID-19, ICU admission, and death. The authors suggest that relevant parties increase COVID-19 vaccination coverage, especially in the elderly population.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.26 no.4
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• pp.193-200
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• 2023

Purpose: Crohn's disease (CD) is a chronic, idiopathic bowel disorder that can progress to partial or complete bowel obstruction. At present, there are no reliable diagnostic tests that can readily distinguish between acute inflammatory, purely fibrotic and mixed inflammatory and fibrotic. Our aim is to study the utility of contrast enhanced ultrasound (CEUS) in combination with shear wave elastography (SWE) to differentiate fibrotic from inflammatory strictures in children with obstructive CD of the terminal ileum. Methods: Twenty-five (19 male) children between 2016-2021 with CD of the terminal ileum were recruited into the study. Among these patients, 22 had CEUS kinetic measurements of tissue perfusion, including wash-in slope (dB/sec), peak intensity (dB), time to peak intensity (sec), area under the curve (AUC) (dB sec), and SWE. In total, 11 patients required surgery due to bowel obstruction. Histopathologic analysis was performed by a pathologist who was blinded to the CEUS and SWE test results. Results: Patients that underwent surgical resection had significantly higher mean area under the curve on CEUS compared to patients responsive to medical therapy (p=0.03). The AUC also correlated with the degree of hypertrophy and the percent fibrosis of the muscularis propria, as determined by histopathologic grading (p<0.01). There was no difference in the mean elastography measurements between these two patient groups. Conclusion: CEUS is a useful radiological technique that can help identify pediatric patients with medically refractory obstructive fibrotic strictures of the terminal ileum that should be considered for early surgical resection.

• Restorative Dentistry and Endodontics
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• v.48 no.4
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• pp.36.1-36.15
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• 2023

Objectives: This study aimed to compare the effectiveness of a single-file reciprocating system (WaveOne Gold, WOG) and a multi-file rotary system (ProTaper Universal Retreatment, PTUR) in removing canal filling from severely curved canals and to evaluate the possible adjunctive effects of XP-Endo Finisher (XPF), the Self-Adjusting File (SAF), and an erbium, chromium: yttrium, scandium, gallium garnet (Er,Cr:YSGG) laser using microcomputed tomography (µCT). Materials and Methods: Sixty-six curved mandibular molars were divided into 2 groups based on the retreatment technique and then into 3 based on the supplementary method. The residual filling volumes and root canals were evaluated with µCT before and after retreatment, and after the supplementary steps. The data were statistically analyzed with the t-test, Mann-Whitney U test, analysis of covariance, and factorial analysis of variance (p < 0.05). Results: PTUR and WOG showed no significant difference in removing filling materials (p > 0.05). The supplementary techniques were significantly more effective than reciprocating or rotary systems only (p < 0.01). The supplementary steps showed no significant differences in canal filling removal effectiveness (p > 0.05), but XPF showed less dentin reduction than the SAF and Er,Cr:YSGG laser (p < 0.01). Conclusions: The supplementary methods significantly decreased the volume of residual filling materials. XPF caused minimal changes in root canal volume and might be preferred for retreatment in curved root canals. Supplementary approaches after retreatment procedures may improve root canal cleanliness.

• The Journal of the Acoustical Society of Korea
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• v.28 no.8
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• pp.774-780
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• 2009

This paper proposes a transmitted power saving method for underwater acoustic sensors considering the acoustic wave propagation characteristic that propagation loss increases more rapidly in higher frequency band. In the proposed scheme, sensor nodes are divided into a few groups based on the distance between sink node and the sensor node, and each group uses its own frequency band. The node group with longer distance uses lower frequency and the node group with shorter distance uses higher frequency. By means of such a distance-dependent frequency allocation, all sensor nodes are able to maintain a certain target signal-to-noise ratio (SNR), but also save transmitted power. In addition, the optimum size of node group is obtained, and also a frequency allocation algorithm is proposed accordingly. Numerical results show that the proposed scheme saves transmitted power by more 10 dB comparing non-grouping methods.

• Korean Circulation Journal
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• v.53 no.9
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• pp.621-631
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• 2023

Background and Objectives: The morphology-voltage-P-wave duration (MVP) electrocardiography (ECG) risk score is a newly defined scoring system that has recently been used for atrial fibrillation (AF) prediction. The aim of this study was to evaluate the ability of the MVP ECG risk score to predict AF in patients with an implantable cardioverter defibrillator (ICD) and heart failure with reduced ejection fraction in long-term follow-up. Methods: The study used a single-center, and retrospective design. The study included 328 patients who underwent ICD implantation in our hospital between January 2010 and April 2021, diagnosed with heart failure. The patients were divided into low, intermediate and high-risk categories according to the MVP ECG risk scores. The long-term development of atrial fibrillation was compared among these 3 groups. Results: The low-risk group included 191 patients, the intermediate-risk group 114 patients, and the high-risk group 23 patients. The long-term AF development rate was 12.0% in the low-risk group, 21.9% in the intermediate risk group, and 78.3% in the high-risk group. Patients in the high-risk group were found to have 5.2 times higher rates of long-term AF occurrence compared to low-risk group. Conclusions: The MVP ECG risk score, which is an inexpensive, simple and easily accessible tool, was found to be a significant predictor of the development of AF in the long-term follow-up of patients with an ICD with heart failure with reduced ejection fraction. This risk score may be used to identify patients who require close follow-up for development and management of AF.

• The Journal of the Korea Contents Association
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• v.20 no.7
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• pp.127-138
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• 2020

This study aims to analyze influences of self-perceived health, participation in social activities on life satisfaction and mediating effect of participation in social activities of the elderly by age group. For this, Structural Equation Model(SEM) was implemented by using data of the 6th wave of KLoSA with 2,106 young-olds and 2,219 old-olds. The results are as follows: The young-old elderly had higher level of self-perceived health, higher participation in social activities, and higher life satisfaction than the old-old elderly, and the mediating effect of participation in social activities was founded only in the young-old elderly. As a result of multi-group analysis, the influence of self-perceived health on life satisfaction was confirmed by no difference between both groups and the influence of self-perceived health on the participation in social activities was relatively higher in the old-old elderly. In the path of participation in social activities on the life satisfaction, the young-old elderly were found to have a significant effect. Through above results, the intervention plan considering the differences between groups was discussed in order to improve the elderly's life satisfaction.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.2
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• pp.182-197
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• 1993

Algal community on the subtidal rocky zone of the South Sea of Korea was divided into two or three sequencing zones. The upper subtidal zone was characterized by the wave exposure-tolerant surf wrack(Pachymeniopsis, Gigartina), which formed dense swirling carpet. Its vertical range was from the surface to $3{\sim}5$ meters in depth, and more deeply extended in turbid waters including Sorido, Yokchido, Pijindo, Manjedo. The mid subtidal zone ranging from 5 to 25 meters in depth was characterized by a large brown algal forest (Ecklenia, Sargassum). But it was generally unrecognizable in that turbid waters, in which the vertical limit of vegetation was at most $10{\sim}15$ meters in depth. The low subtidal zone was characterized by a general lack of algal species and was not easily distinguished from the mid or sometimes from the upper zone. There was a distinct difference in abundance of vegetation between turbid waters and clear waters including Munsom, Kwantaldo, Yosodo, Hongdo, Ch'ujado. In turbid waters the vegetation was much poorer because the tubidity caused from the muddy sediment inhibited an algae to settle down and to grow up. On the basis of the phytogeographical methods using UPGMA, the 10 studied islands were classified into two groups, Munsom and the others. This floristic discontinuity between the two groups might be caused from the difference of water temperature.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.5
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• pp.545-566
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• 1999

The use of pure titanium and titanium alloys have been increased recently in fixed, removable prosthodontics and implant fields as a framework. But when they were used for superstructures of implant or metal framework of removable prosthesis, welding is necessary to reconnect the fracture site to control the casting distortions. To overcome the difficulties in soldering the titanium due to high oxidation property, much effort have been devoted. In this study, some of mechanical properties were compared between pure titanium and Ti-6Al-4V alloy by using after welding, electron beam welding technique and tungsten arc welding. Mechanical properties such as tensile strength, yield strength, elongation and microhardness were measured. And, in order to compare the effect of welding site and surrounding metal tissue according to the welding condition, SEM photographs were taken and element distribution was observed by Wave Dispersion Spectroscopy. Through analyses of the data, following results were obtained; 1. In items such as tensile strength, yield strength and elongation according to the welding techniques of pure titanium, only tungsten arc welded group showed significant lower value than other groups(P<0.05). 2. In items such as tensile strength and yield strength according to the welding techniques of Ti-6Al-4V alloy, control group and tungsten arc welded group showed significant difference among all the groups(P<0.05). 3. Ti-6Al-4V alloy exhibited significantly greater elongation than control group when the laser welding method and electron beam welding method were used, and elongation showed increasing tendency. 4. Pure titanium specimens exhibited increasing tendency of microhardness regardless of the weld-ing technique applied, and especially tungsten arc welded group demonstrated a great increase of microhardness than parent metal. 5. There was no hardness change in laser welded group and electron beam welded group of Ti-6Al-4V alloy, but in tungsten arc welded group, hardness changed greatly from parent metal to weld seam. 6. Through the metallographic examination and scanning electron microscopy, laser welding caused central fusion and recristallizations were formed and tungsten arc welding caused localized fusion to 0.3-0.7mm from the surface.