• Textile Coloration and Finishing
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• v.32 no.4
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• pp.239-244
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• 2020

Polyethylene (PE) micro-fiber have been prepared at different hot air temperature (60, 80 and 100 ℃) and different pressure (20, 40, 60 and 80 kPa) by melt centrifugal spinning technique. The parameters of melting centrifugal spinning including polymer contents, rotational velocity, temperature of hot air and pressure were optimized for the fabrication process. The study showed that 8000 rpm rotational velocity, 80 ℃ heated hot air and 40 kPa air pressure are the best condition to obtain uniform and strong PE fiber. The prepared PE fibers were analyzed by field emission scanning electron microscope and universal testing machine and found that fibers with reduced diameter and improved tensile strength are obtained at hot air condition.

• Bulletin of the Korean Chemical Society
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• v.19 no.3
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• pp.349-353
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• 1998

Solvolysis rates of substituted 2-aryl-1,1-dimethylethyl bromides (1) were determined in a variety of solvents such as aqueous mixtures of ethanol, acetone, 2,2,2-trifluoroethanol, and also mixtures of ethanol and TFE at 25 ℃, 35 ℃, and 45 ℃. The solvent effects were analyzed in terms of Winstein-Grunwald equation. The solvent effects of 1-4-MeO failed to give a single linear correlation against either Y or YCl (YBr), but exhibited a wide split pattern which could not be related to the solvent nucleophilicity. On the other hand 1-4-CH3 and 1-H gave a fairly good linearity. In the case of 1-4-MeO, a fairly good linearity was observed against YΔ defined from the solvolysis of 4-methoxyneophyl tosylate. It is assumed that resonance interaction between reaction site and aryl-π-system operates to give charge delocalization regardless of the different solvolysis mechanisms. The Hammett-Brown treatment of the solvolytic rate constant of compounds 1 was obtained non-linear two separated lines of - 1.06 to - 1.46, suggesting of mechanistic changeover from kc-ks to kΔ on going from electron-withdrawing to electron-donating substituents as a basis of 4-CH3 group.

• Korean Journal of Metals and Materials
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• v.49 no.5
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• pp.406-410
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• 2011

ZnO nanorods were prepared by the electrodeposition route on conductive Au/Si substrates. The effects of deposition time on the microstructural evolution and optical properties of ZnO nanorods were investigated. With increasing deposition time from 1 h to 20 h, the diameter and length of the ZnO nanorods increased gradually to about 328 nm and 6.55${\mu}m$, respectively. The ZnO nanorods were dense and vertically well-aligned. The photoluminescence (PL) peaks corresponding to the near band edge of ZnO were observed. With increasing deposition time, the intensity of PL peaks increased with nanorod growth up to 4 h and then decreased. This might be due to the degradation of crystal quality caused by merging of nanorods.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.5
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• pp.125-134
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• 2008

A great number of RFID authentication protocols have been proposed for the secure RFID system. These are typically divided into three types according to primitive that they use : Hash-based, Re-encryption based, and XORing-based protocol. The well-known attacks in RFID system are eavesdropping. impersonating, location tracking, and so on. However, existing protocols could not provide security against above attacks, or it was not efficient to search for tags on database. Therefore, in this paper we present a protocol which is secure against above attacks by using hash function and makes Database search tags easily by attaining the state information of previous session through the shared values with all tags and database.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.32 no.1
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• pp.43-47
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• 2021

Voice therapy is effective in many voice and speech disorders. However, patients have low accessibility to therapeutic facilities due to disease-unrelated reasons such as lack of time and pandemic of COVID-19. Contactless voice therapy could be an alternative and may helpful to all patients with voice and speech problems. We developed contactless voice and speech therapy program on the necessity of improving accessibility. Herein, we report the first case of voice therapy to 30 year-old female patient who complained voice change after total thyroidectomy using contactless voice and speech therapy service platform in Korea.

• Journal of architectural history
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• v.31 no.1
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• pp.51-60
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• 2022

In the 16~17th centuries, the construction of T-shaped pavilion in Gyeongsangbuk-do was centered on the families of the Goseong-Lee clan and Andong-Kwon clan, who had a lot of exchanges with each other near Andong. It can be presumed that the complex structure of the T-shaped pavilion was intended to represent the technology, economic power, and social influence of the clan. After the 18th century, construction areas spread and construction subjects were diversified, but the number of new constructions decreased. It can be seen that T-shaped pavilion was erected and used for public purposes rather than personal reasons in terms of layout or flat scale. The roof of the T-shaped pavilion is very diverse depending on the wooden structure, the height of the roof and the configuration of the apex. The T-shaped pavilion, which combines two parts, has been developed in a way that strengthens not only the appearance but also the structural bonding force. The bonding strength is strengthened through the process of "roof aligning", "roof bonding", "structure connection", and "structure integration", which shows a similar tendency to the age of actual cases.

• Textile Coloration and Finishing
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• v.34 no.1
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• pp.10-19
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• 2022

Humectants are chemical compounds which added to water based pigment inks for DTP (Digital Textile Printing) to prevent evaporation of water. The humectants usually have diol or triol type chemical structures and their -OH groups have possibility to react with functional groups of the binder polymers, such as ester, carboxylic acid, and urethane groups, acting as a crosslinking agent. The crosslinking reactions between polymer binders and humectants in inks can affect touch of the printed fabrics. In this regard, this study aims to investigate effect of chemical structures and added amounts of humectants in pigment ink on touch of dyed fabrics by using 1,6-hexanediol, ethylene glycol, diethylene glycol, and 1,4-buthanediol with various amounts added to the mixture of a black pigment and a polyurethane type binder. Then, color, rubbing strength, touch of the fabrics dyed with the prepared pigment inks were evaluated.

• Journal of Science Education
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• v.45 no.3
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• pp.326-335
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• 2021

In this study, we developed an experimental apparatus to study the principle of rainbow formation. The rainbow is formed through the dispersion, reflection, and refraction of light on water droplets. However, the rainbow cannot be made from a single drop of water. Thus, we devised an apparatus to observe the principle behind the rainbow formation caused by light rays on many water drops. This we deemed would help students understand the formation of the rainbow. We used glass beads as water drops to reproduce the rainbow phenomena. We also materialized the rainbow by changing various variables such as the position of the observer and the height of the light source, etc.

• Journal of Biomedical Engineering Research
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• v.43 no.6
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• pp.399-408
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• 2022

Because arrhythmia occurs irregularly, it should be examined for at least 24 hours for accurate diagnosis. For this reason, this paper developed firmware software for arrhythmia detection and prevented consumption of temporal and human resources and enabled continuous management and early diagnosis. Prior to the experiment, the interval between the R peaks of the QRS Complex was calculated using the Pan-Tompkins algorithm. The developed firmware software designed and implemented an algorithm to detect arrhythmia such as tachycardia, bradycardia, ventricular tachycardia, persistent tachycardia, and non-persistent tachycardia, and a data transmission format to monitor the collected data based on BLE. As a result of the experiment, arrhythmia was found in real time according to the change in BPM as designed in this paper. And the data quality for BLE communication was verified by comparing the sensor's serial communication value with the Android application reception value. In the future, wearable devices for real-time arrhythmia detection will be lightweight and developed firmware software will be applied.

• Journal of the Korean Orthopaedic Association
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• v.56 no.4
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• pp.357-360
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• 2021

The incidence of postoperative ileus (POI) after colonic and abdominal surgery is high. On the other hand, the reported incidence after lower extremity reconstruction ranges from 0.3% to 4.0%. This paper reports an 81-year-old woman who expired due to POI at six days after primary total knee arthroplasty. The risk factors, diagnosis, preventive methods, and treatment of POI were also investigated through literature reviews.