• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.5
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• pp.397-405
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• 2003

Heat and fluid flow in a compressor into which liquid refrigerant is injected for the purpose of reducing discharge gas temperature in a heat pump system has been numerically studied. A mechanistic approach encompassing liquid jet breakup and droplet evaporation has been performed to investigate the effects of liquid injection on the spacial and temporal variation of the gas temperature and pressure inside the compressor cylinder. Various parameters, such as liquid injection mass, time, duration and droplet size, are considered in the present study to elucidate the flow field inside the compressor. As the injection mass is increased, discharge gas temperature is decreased, while the pressure is increased due to the added mass of the injection. For the injected liquid mass corresponding to 15% of the total vapor mass in the cylinder, the discharge gas temperature drops by 22.4 K. It is observed that the droplet size plays a major role in the evaporation rate of the droplets that determines the degree of the discharge temperature drop.

• Journal of the Institute of Convergence Signal Processing
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• v.16 no.1
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• pp.29-34
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• 2015

The ECG(Electrocardiograph) ambulatory test as called Holter is performed usually to diagnose several heart diseases causing different arrhythmias. This paper exposes the insights of the design of a 10-lead ambulatory ECG recorder. Reducing the size and minimizing the power consumption of the ECG recorder are crucial to allow long recording time without causing discomfort to the patient. This paper proposes lower hardware design and differential compression algorithm to extend the maximum 72 hours recording time in consideration of smaller and light-weighted recorder size. The performance results by newly introduced compression algorithm are shown and discussed.

• Korean Journal of Remote Sensing
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• v.38 no.4
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• pp.375-386
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• 2022

The city of Khartoum, the capital of Sudan, was heavily damaged by the flood of the Nile in 2020. Classification using satellite images can define the damaged area and help emergency response. As Synthetic Aperture Radar (SAR) uses microwave that can penetrate cloud, it is suitable to use in the flood study. In this study, Random Forest classifier, one of the supervised classification algorithms, was applied to the flood event in Khartoum with various sizes of the training dataset and number of images using Sentinel-1 SAR. To create a training dataset, we used unsupervised classification and visual inspection. Firstly, Random Forest was performed by reducing the size of each class of the training dataset, but no notable difference was found. Next, we performed Random Forest with various number of images. Accuracy became better as the number of images in creased, but converged to a maximum value when the dataset covers the duration from flood to the completion of drainage.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.1540-1547
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• 2009

Steel frame factories were surveyed in this study in order to explore the possibility of shortening the construction time and save on construction cost through overlapping at the stages of design or construction. In the survey, construction professionals were interviewed in order to collect quantitative data. Hypotheses were then formulated, and the data was thereby analyzed using the simulation technique in order to analyze the effects of the concurrent engineering method on shorter construction time and cost saving. In addition, actual cases were analyzed to determine the overlapping rates of major processes in terms of shorter construction time and cost saving and to analyze the relationship between time and cost due to overlapping.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.05a
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• pp.706-709
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• 2008

With the increasing popularity of P2P file sharing and advancement of mobile technologies, mobile P2P has revealed its attraction. Anonymity has become an increasing requirement in mobile networks. To reduce receiving garbage files, file validation and filtering are other requirements in the mobile P2P environment. If there are effective file filtering and validation mechanism, nodes' battery duration will be saved. In this paper, we do an analysis of security and anonymity in P2P file sharing and exchange system in mobile ad hoc environment, and propose a new efficient anonymous protocol, which can provide anonymity by broadcasting with a probabilistic algorithm and hiding real hop count information, the file validation by the file's special hash value and file filtering mechanism through the collaboration of middle nodes.

• International conference on construction engineering and project management
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• 2011.02a
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• pp.407-412
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• 2011

Recently, the Malaysian government had been developing new technologies to the construction industry and one of them is the Industrialised Building System (IBS). The government urged that IBS is 100% utilized in all construction projects. It is believed that the application of IBS helps in reducing construction duration and cost, solving the problems of overflow of foreign workers in the site and improving performance and appearance of a structure. However, there are some parties like the contractor who feel reluctant to utilize this system because there are risks. They worry that their trades will be affected as IBS construct a structure using components which are manufactured in a factory and assemble on site. Therefore, this research is to find out whether IBS benefits the country's economy by focusing on the business created by investing in IBS. A comprehensive supply chain for IBS will be developed to compare with the traditional construction supply chain as to determine businesses or trades created and eliminated. This paper is looking at the theoretical framework about business opportunities due to the Government policy on embarking IBS.

• Phonetics and Speech Sciences
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• v.13 no.4
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• pp.75-87
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• 2021

The purpose of this study was to investigate, longitudinally, interruption behavior which children who do stutter (CWS), children who do not stutter (CWNS) and their mothers and relationship with disfluency of children showed during interactions with their mothers. Subjects for this study consisted of 2-5 year old CWS (male 2 and female 4), an age-matched group of CWNS (male 3 and female 3), and their mothers. Frequencies of normal disfluency (ND) and abnormal disfluency (AD) in children group and frequency of interruption and simultalk duration in children and mothers group were measured two times (initial visit and 12 months later) over the course of one year. As a result, no significant difference was observed in frequency of interruption and simultalk duration both between two mother groups and between two child groups at initial visit and 12 months later. However, frequency of interruption increased significantly over the course of one year in CWS group. A significant group difference was found in frequency of interruption of mothers but, no significant difference was observed in simultalk duration of mothers at initial visit. In the CWS·mothers group, no factors were related with disfluency of children at initial visit and 12 months later. These findings suggest that interruption is not just negative behavior, and that reducing interruption should be considered in child·parent interaction therapy for CWS.

• Journal of Oral Medicine and Pain
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• v.21 no.1
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• pp.173-182
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• 1996

This study was performed to provide the information on the clinical characteristics of the most common paroxysmal pain disorder in maxillofacial region, trigeminal neuralgia, and the effects and side effects of carbamazepine. The patients who visited Orofacial Pain Clinic, Dept. of Oral Diagnosis, Seoul National University Dental Hospital for treating paroxysmal pain were studied by history taking, clinical examination, and radiography. Sixty-two patients(male 20, female42) without any clinical and radiological abnormalities were Included. The change of pain, blood tests, and side effects were investigated periodically after administration of carbamazepine. The obtained results were as follows : 1. Almost all patient with trigeminal neuralgia were over the age of forties and it was more common in women. 2. Trigeminal neuralgia was more right sided and the involved nerve was in the order of maxillary n., mandibular n., and ophthalmic n. 3. The mean duration of suffering was 20.7 months. Eighty percent of patients had apparent trigger area. 4. The duration of pain attack was in the older of several seconds, 1 min. to 5 min., more than 10 min., and 5 min. to 10 min. The frequency of pain attack was in the order of more than 10 per day, 6-10 per day, and 1-5 per day. 5. The clinic the patients had visited for reducing neuralgic pain was in the order of dental clinic, neurology, oriental medicine, otolaryngology, and pharmacy. 6. Unnecessary dental treatments for reducing neuralgic pain were performed in 41.9% of the patients. Almosit all treatments were irreversible ones such as endodontic treatment and tooth extraction. 7. The initial mean VAS was 8.6, but it was decreased to 3.8 after 1 month, to 2.7 after 2 months. Almost all patients showed decreased pain with 200-600mg/day of carbamazepine to 6 months. 8. WBC counts, especially neutrophil counts, was decreased in 1 week after administration of carbamazepine but reached initial level after 1 month. SGOT, SGPT, and creatinine did not show any significant change. 9. Blood pressure was not changed significantly after administration of carbamazepine. 10. Almost patients did not show any apparent side effects, but drowsiness, dizziness, skin itching, constipation, and gastric irritation were occurred in some patients.

• Journal of Korean Public Health Nursing
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• v.20 no.1
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• pp.39-56
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• 2006

Objectives: To investigate the drinking and smoking habits among the community residents of a city. Methods: We surveyed 1.973 adults from October 1, 2005 to November 16, 2005. The data collected on alcohol drinking habits involved frequency, age of initiation, amount of alcohol consumed, number of attempts to reduce consumption and reasons for reducing it. The data collected on smoking habits involved amount, age of initiation, duration, situations, and the number of attempts to quit smoking. These were analyzed with frequency, percentage, mean, standard deviation, $x^2$-test, t-test and ANOVA. Results: The rate of drinking was 67.4%; 83.1% among males, and 52.5%among females. Among all drinkers, the largest group (29.8%) drank once or twice a week. The mean age of initiation was 21.2 years; 19.9 among males, and 22.8 among females. The average consumed amount was 5.8 glasses; males consumed 7.4 glasses, and females 3.3 glasses. The consumption was the highest among those in fifties. The rate of attempts to reduce drinking was 33.4%, mainly for health reasons. The rate of smoking was 38.0%; 72.4% among males, and 5.5% among females. Among all smokers, the largest group (44.1%) smoked between 11 and 20 cigarettes per day. The mean of the age of initiation was 20.7 years; 20.3 among males, 25.6 among females. The mean smoking duration was 20.9 years; 21.3 years among males, and 16.2 years among females. The main reason for the initial attempt was curiosity. The most common situation for smoking was after dinner. The rate of attempts to quit smoking was 77.1%, mainly out of concern for one's health. Alcohol consumption among smokers was higher than among any other group of nonsmokers. Also, the age of drinking initiation among smokers was lower than among any other group of nonsmokers. Conclusion: This study highlighted the actual data on drinking and smoking habits among community residents. The study can be utilized for creating programs aiming at reducing the consumption of alcohol and tobacco or stopping it altogether. Therefore, it is now possible to assess the indicators for interventions in each population group. Finally, the groups of heavy drinkers and smokers are expected to be given priority for intervention program.

• Geotechnical Engineering
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• v.13 no.6
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• pp.25-36
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• 1997

A degree of consolidation at any time can be evaluated by using cone penetration test after soil improvement. In this case, after stopping the penetration of a piezocone, pore pressure dissipation(PPD) best is carried out until the pore pressure remains constant. Since the hydraulic conductivity of soft ground is very small, it takes very long time to finish the PPD test. This research is performed to develop a method overcoming this problem of the PPD test and reducing the test time. The analyses are carried out in the following ways : an equilibrium pore pressure can be determined by using pore pressure measured in the middle of the test, which is predicted by hyperbolic, Asaoka and Hoshino methods. And this equilibrium pore pressure is compared with the one measured in a test of long duration. As a result of the study, it is found that Hoshino method is the best way to predict the equilibrium pore pressure in a teat of short duration. And it is proposed as a methodology to fond a minimal time in which we can get an equilibrium pore pressure.