• Nuclear Engineering and Technology
• /
• v.54 no.11
• /
• pp.4102-4110
• /
• 2022

Aiming at high-power and long-pulse operation up to 1000 s, some improvements have been made for both 2.45 GHz and 4.6 GHz lower hybrid (LH) systems during the recent 5 years. At first, the guard limiters of the LH antennas with graphite tiles were upgraded to tungsten, the most promising material for plasma facing components in nuclear fusion devices. These new guard limiters can operate at a peak power density of 12.9 MW/m². Strong hot spots were usually observed on the old graphite limiters when 4.6 GHz system operated with power >2.0 MW [B. N. Wan et al., Nucl. Fusion 57 (2017) 102019], leading to a reduction of the maximum power capability. With the new limiters, 4.6 GHz LH system, the main current drive (CD) and electron heating tool for EAST, can be operated with power >2.5 MW routinely. Long-pulse operation up to 100 s with 4.6 GHz LH power of 2.4 MW was achieved in 2021 and the maximal temperature on the guard limiters measured by an infrared (IR) camera was about 540 ℃, much below the permissible value of tungsten material (~1200 ℃). A discharge with a duration of 1056 s was achieved and the 4.6 GHz LH energy injected into the plasma was up to 1.05 GJ. Secondly, the fully-active-multijunction (FAM) launcher of 2.45 GHz system was upgraded to a passive-active-multijunction (PAM), for which the density of optimum coupling was relatively low (below the cut-off value). Good coupling with reflection coefficient ~3% has been achieved with plasma-antenna distance up to 11 cm for the new PAM. Finally, in order to eliminate the effect of ion cyclotron range of frequencies (ICRF) wave on 4.6 GHz LH wave coupling, the location of the ICRF launcher was changed to a port that is located 157.5° toroidally from the 4.6 GHz LH system and is not magnetically connected.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.11
• /
• pp.61-70
• /
• 2008

Load settlement behaviors and load transfer characteristics of rock-socketed pile subjected bi-directional load at pile tip were investigated using bi-directional pile load tests (BD PLT) performed on ten large-diameter drilled shafts at four sites. Based on test results, additional pile-toe displacement ($w_{bs}$) by coupled soil resistance was analyzed, and thus equivalent top loaded load-settlement curve of pile subjected bi-directional load was proposed by taking into account the coupled soil resistance. Through comparisons with field case studies, it is found that for test piles there exists effect of coupled soil resistance, which is represented by wbs, and thus an equivalent curve obtained by existing uncoupled methods can overestimate bearing capacity of piles by BD PLT. On the other hand, the analysis by the proposed method with soil coupling effect has a considerably larger settlement when compared with the results by uncoupled load transfer method and estimates reasonable load-settlement behaviors of test piles. In case of pile socketed in high strength rocks, however, effects of coupled soil resistance can be neglected.

• Journal of the Korea Society of Computer and Information
• /
• v.14 no.3
• /
• pp.1-11
• /
• 2009

XQuery query proposed by W3C is one of the standard query languages for XML data and is widely accepted by many applications. Therefore the studies for efficient Processing of XQuery query have become a topic of critical importance recently and the optimization of XQuery query is one of new issues in these studies. However, previous researches just focus on the optimization techniques for a specific XML data management system and these optimization techniques can not be used under the any XML data management systems. Also, some previous researches use predefined XML data structure information such as XML schema or DTD for the optimization. In the real situation, however applications do not all refer to the structure information for XML data. Therefore, this paper analyzes only a XQuery query and optimize by using itself of the XQuery query. In this paper, we propose 3 kinds of optimization method that considers the characteristic of XQuery query. First method removes the redundant expressions described in XQuery query second method replaces the processing order of operation and clause in XQuery query and third method rewrites the XQuery query based on FOR clause. In case of third method, we consider FOR clause because generally FOR clause generates a loop in XQuery query and the loop often rises to execution frequency of redundant operation. Through a performance evaluation, we show that the processing time for rewritten queries is less than for original queries. also each method in our XQuery query optimizer can be used separately because the each method is independent.

• Journal of the Korean Society of Food Culture
• /
• v.25 no.1
• /
• pp.100-107
• /
• 2010

This study was performed to compare the dietary intake and food sources of zinc (Zn), using a database of Zn composition developed in this study, between elementary schoolchildren in a remote rural area (RA, n=58, $9.9{\pm}1.7\;yrs$) and those in an urban area (UA, n=60, $9.4{\pm}1.8\;yrs$) in Chungnam province in Korea. A dietary survey for three days by food record method was performed. All kinds of foods (n=273) consumed by subjects were collected by aliquot sampling method, and the Zn content of these foods were analyzed by wet technique. The results showed that the daily mean intakes of energy, calcium, iron, and vitamin C from diet in the RA were in the range of 49-88% of the Korean DRI (KDRI), while those in the UA were similar to or greater than the KDRI, except for calcium and iron. The daily mean intake of Zn from the RA diet was $7.0{\pm}0.5\;mg/d$ ($114.1{\pm}8.4%$ of the KDRI), and $16.0{\pm}1.0\;mg/d$ ($258.3{\pm}16.3%$ of the KDRI) in that of the UA (p<0.001). The percentage of dietary intake of Zn less than 2/3 of the KDRI was 19.0% in the RA, in comparison to 1.7% in the UA. Those in the RA consumed Zn from plant foods more often than did those in the UA (p<0.001). Beef rib stew was the food source with highest Zn amount for the total subjects, followed by beef rib meat, roasted; and beef soup w/seasoned red pepper sauce. These results showed that some children in the RA had poor Zn nutrition based upon low intakes and poor food sources of Zn, while overall, children in the UA had good Zn nutrition. Therefore, those in RAs should have their Zn nutrition improved through government policy and nutrition education.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.4A
• /
• pp.565-571
• /
• 2008

Recently, the evaluation technique using NDT (Nondestructive Technique : NDT) is widely utilized because it makes little damage on RC (Reinforced Concrete : RC) structures. The techniques using electromagnetic properties (EM properties) are also attempted for the evaluation of the performance of concrete which is nonmetallic. For the economic manufacturing of concrete material, sea-sand is often used as aggregate, however, chloride ion in concrete has direct effects on steel corrosion and EM properties. In this study, OPC mortar specimens with 5 different chloride amount (0.0, 0.6, 1.2, 2.4, and $3.6kg/m^3$) and 3 different water-cement ratios (45%, 55%, and 65%) are prepared in order to investigate the EM properties corresponding to concrete properties. The EM properties of conductivity and dielectric constant are measured in the frequency range over 0.2~20 GHz. To facilitate the comparison of EM properties with chloride content, average values are taken respectively for the conductivity and dielectric constant measured over the 5~20 GHz frequency range. According to the results of this experiment, dielectric constant and conductivity are increased with lower W/C ratio and larger amount of chloride content.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.4 no.1
• /
• pp.21-32
• /
• 1994

$CaF_2$ crystals were grown with various growth rates by Bridgman method, and the electrical properties of these were studied to examine the changes of ionic conductivities with growth rates by AC Impedance Analyzer. As the growth rates were higher, $CaF_2$ crystals were grown to polycrystals from single crystal. And as grain boundaries and various defects were altered, the ionic conductivities were changed dramatically. $YF_3$ added to $CaF_2$ for disorderizing $CaF_2$ structure and improving the number of $F^-$ carriers and vacancies in $CaF_2$ crystals. Then $Ca_{1-x}Y_XF_{2+X}$ crystals were gained. And the ionic conductivities of $Ca_{1-x}Y_XF_{2+X}$ crystals were investigated with $YF_3$ addition. The ionic conductivities of $CaF_2$ and $Ca_{1-x}Y_XF_{2+X}$ crystals with temperatures were compared. In addition, the effects of clusterings and defects on the electrical properties of solid electrolytes were researched.

• Journal of Practical Agriculture & Fisheries Research
• /
• v.19 no.1
• /
• pp.39-49
• /
• 2017

The present study conducted a comparison on tree growth and productivity of high-density apple orchards by several orchard management systems: making scaffolds by heading-back and thinning out pruning (T-1), maintaining scaffolds upward and bearing shoots downward (T-2), managing branches slightly upward without heading-back (T-3), keeping leaders downward and shoots pending (T-4), maintaining leaders high and branches horizontal with severe pinching (T-5), making leaders with lower branches vigorous and upper shoots pending (T-6), and controlling very high planting density with bending branches (T-7). In conclusion, the orchards of (T-5) and (T-6) management systems showed a superior performance in controlling tree growth, productivity, and quality of fruits. Also, superior management efficiency was obtained in the orchards of (T-5) and (T-6).

• Korean Journal of Radiology
• /
• v.22 no.6
• /
• pp.994-1004
• /
• 2021

Objective: To extract pulmonary and cardiovascular metrics from chest CTs of patients with coronavirus disease 2019 (COVID-19) using a fully automated deep learning-based approach and assess their potential to predict patient management. Materials and Methods: All initial chest CTs of patients who tested positive for severe acute respiratory syndrome coronavirus 2 at our emergency department between March 25 and April 25, 2020, were identified (n = 120). Three patient management groups were defined: group 1 (outpatient), group 2 (general ward), and group 3 (intensive care unit [ICU]). Multiple pulmonary and cardiovascular metrics were extracted from the chest CT images using deep learning. Additionally, six laboratory findings indicating inflammation and cellular damage were considered. Differences in CT metrics, laboratory findings, and demographics between the patient management groups were assessed. The potential of these parameters to predict patients' needs for intensive care (yes/no) was analyzed using logistic regression and receiver operating characteristic curves. Internal and external validity were assessed using 109 independent chest CT scans. Results: While demographic parameters alone (sex and age) were not sufficient to predict ICU management status, both CT metrics alone (including both pulmonary and cardiovascular metrics; area under the curve [AUC] = 0.88; 95% confidence interval [CI] = 0.79-0.97) and laboratory findings alone (C-reactive protein, lactate dehydrogenase, white blood cell count, and albumin; AUC = 0.86; 95% CI = 0.77-0.94) were good classifiers. Excellent performance was achieved by a combination of demographic parameters, CT metrics, and laboratory findings (AUC = 0.91; 95% CI = 0.85-0.98). Application of a model that combined both pulmonary CT metrics and demographic parameters on a dataset from another hospital indicated its external validity (AUC = 0.77; 95% CI = 0.66-0.88). Conclusion: Chest CT of patients with COVID-19 contains valuable information that can be accessed using automated image analysis. These metrics are useful for the prediction of patient management.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.30 no.1
• /
• pp.63-72
• /
• 2024

Poly (butylene adipate-co-terephthalate) (PBAT) is one of the representative biodegradable polymers with high ductility and processability to replace petroleum-based polymers. Many investigations have been conducted to broaden the applications of PBAT in a variety of industries, including the food packaging, agricultural mulching film, and logistics and distribution fields. Foaming process is widely known technique to generate the cell structure within the polymer matrix, offering the insulation and light weight properties. However, there was no commercially feasible foam product based on biodegradable polymers, especially PBAT, and maintaining a proper melt viscosity of the polymer would be a key parameter for the foaming process. In this study, chemical foaming agent and cross-linking agent were introduced to PBAT, and a compression molding process was applied to prepare a foam sheet. The correlation between cell morphological structures and mechanical and physical properties was evaluated. It was found that PBAT with foam structures effectively reduced the density and thermal conductivity, allowing them to be suitable for applications such as insulation and lightweight packaging or cushion materials.

• Clinics in Shoulder and Elbow
• /
• v.26 no.4
• /
• pp.357-365
• /
• 2023

Background: The purpose of this study was to evaluate the effect of concomitant open distal clavicle excision (DCE) on postoperative clinical outcomes and incidence of acromial and scapular stress fractures (ASFs) in patients with symptomatic acromioclavicular joint osteoarthritis (ACJ OA) undergoing reverse total shoulder arthroplasty (RTSA). Methods: A single-surgeon retrospective cohort study was conducted including patients who underwent primary elective RTSA with or without DCE from 2015 to 2019 with a minimum 6-month follow-up period. Shoulder active range of motion (AROM) and visual analog scale (VAS) pain were recorded preoperatively and postoperatively. ASFs and other adverse events were identified using postoperative notes and/or radiographs. Characteristics and outcomes were compared between the RTSA and RTSA-DCE groups. Results: Forty-six RTSA patients (mean age, 67.9±8.7 years; 60.9% male; mean follow-up, 24.9±16.6 months) and 70 RTSA-DCE patients (mean age, 70.2±8.9 years; 20.0% male; mean follow-up, 22.7±12.9 months) were included. There were no significant intergroup differences in rates of ASF (RTSA, 0.0% vs. RTSA-DCE, 1.4%; P=1.00), stress reactions (RTSA, 8.7% vs. RTSA-DCE, 11.4%; P=0.76), reoperation, revision, or infection (all P>0.05), or in pre-to-postoperative reduction in VAS pain (P=0.17) at latest follow-up. However, the RTSA-DCE group had greater pre-to-postoperative improvement in flexion AROM (RTSA, 43.7°±38.5° vs. RTSA-DCE, 59.5°±33.4°; P=0.03) and internal rotation (IR) AROM (P=0.02) at latest follow-up. Conclusions: Concomitant DCE in RTSA improves shoulder flexion and IR AROM, alleviates shoulder pain, and does not increase the risk of ASFs. Level of evidence: III.