• Composites Research
• /
• v.23 no.2
• /
• pp.1-9
• /
• 2010

This study analyzes the apparent fracture toughness of a thick-walled cylinder with a functionally graded material (FGM) coating at the inner surface of the cylinder. The cylinder is assumed to have a single radial edge crack emanating from its inner surface. The crack surfaces and the inner surface of the cylinder are subjected to an internal pressure. The incompatible eigenstrain developed in the cylinder due to nonuniform coefficient of thermal expansion as a result of cooling from sintering temperature is taken into account. Based on a method of evaluating stress intensity factor introduced in our previous study, an approach is developed to calculate apparent fracture toughness. The approach is demonstrated for a cylinder with a TiC/$Al_{2}O_{3}$ FGM coating and some numerical results of apparent fracture toughness are presented graphically. The effects of material distribution profile, cylinder wall thickness, application temperature, and coating thickness on the apparent fracture toughness are investigated in details. It is found that all of these factors play an important role in controlling the apparent fracture toughness of the cylinder.

• Economic and Environmental Geology
• /
• v.39 no.4 s.179
• /
• pp.441-450
• /
• 2006

The on-land seismic survey in Korea was begun in mid-1960s. Kim et al.(1967) of Korea Geological Survey reported on the result of gravity and seismic reflection surveys conducted in the Pohang area for the period of 1963-64 to assess its possibility of oil entrapment. Hyun and Kim (1966) carried out a refraction survey on the tunnel wall. Since then, the KGS geophysicists had conducted seismic surveys on Kyungsang sedimentary basin as a main project for several years. In 1970s, on-land seismic surveys had been conducted for various purposes such as site investigation for the nuclear power plants and industrial complex, exploration for ground water, mineral resources and underground tunnel. The first reflection survey with CMP acquisition was attempted in 1978 by using a digital recording system. But most of on-land seismic surveys had employed the refraction method until 1980s. In 1990s, high resolution reflection and various borehole seismic surveys such as tomography, uphole, downhole, cross-hole methods have been attempted by universities and engineering companies. The applications of on-land seismic surveys have been enlarged for both academic and industrial purposes such as investigation of geologic structure of the fault and tidal flat area, construction of highway, railroad and dam, geothermal energy and mineral resource exploration, environmental assessment for waste disposal sites and archaeological investigations. In 2002, the first crustal seismic survey was carried out on the profile of 294km length across the whole peninsular. It is expected that the advanced technology and experience acquired through offshore seismic surveys, which have been conducted in continental shelf of Korea and foreign oil fields, will stimulate the more active on-land seismic explorations.

• Korean Journal of Head & Neck Oncology
• /
• v.14 no.1
• /
• pp.46-53
• /
• 1998

Background: Hypopharyngeal cancer represents about one-third the incidence of laryngeal cancer which is the most common cancer in head and neck area. Although there have been numerous reports regarding its clinical and statistical characteristics, more precise and ample data should be collected and analyzed in this country. Objectives: This study was designed to evaluate the pattern and patient's profile of the hypopharyngeal cancer, and we reviewed the treatment outcomes to search for an index of treatment modalities. Materials and Methods: The authors retrospectively analyzed 73 cases of hypopharyngeal cancer treated at Yonsei Medical Center during the 10-year period from 1985 to 1994. Five-year survival rate was calculated according to the primary site, clinical stage and treatment modality. Results: The incidence was predominated in male by 9 to 1 and peak incidence was 6th and 7th decades. Pyriform sinus was the main primary site(80.8%) followed by posterior hypopharyngeal wall(13.7%) and postcricoid area(5.5%). Advanced stage cancers(87.7%) were more common than early stage cancers. Radiotherapy(60.3%) was the most commonly used as primary treatment modality. Neck node metastasis was early occurred even in early stage cancers(61.5%), and overall rate of neck node metastasis was 69.9%. All surgical cases received procedures more than total laryngectomy and partial pharyngectomy. The most common cause of death was primary failure(81.5%) and it was highest in radiotherapy group. Five-year survival rate was significantly high in surgery group(90.9%). The overall 5-year survival rate of hypopharyngeal cancer was 30.3%. Conclusion: High index of suspicion should be required for early diagnosis. Also, surgery may be recommended for the primary treatment modality in advanced stage cancers.

• Journal of Radiation Protection and Research
• /
• v.33 no.1
• /
• pp.35-40
• /
• 2008

A distillation tower is one of the important facilities which separates and refines a crude oil stream according to certain boiling points. Its operation efficiency can affect the productivity of a refinery substantially. The objective of this study is to elucidate some operational information on the internal conditions of a distillation tower from a measurement of density profile by using a sealed gamma-ray source and a radiation detector. Gamma radiation counts were measured by a BGO detector positioned diametrically outside the tower-wall, opposite to the gamma source(Co-60) as the detector and the source were lowered concurrently. From the results, structural abnormality of the trays was not found inside the tower. Considering the flow distribution patterns, however, a vapor phase was dominantly formed at the upper part of the tower and a liquid phase at the lower part. From the gamma scanning of the distillation tower, it is anticipated that the gamma absorption technique can be used as an important tool for confirming the structural soundness of trays and investigating flow distribution in refinery facilities.

• Wind and Structures
• /
• v.16 no.4
• /
• pp.301-322
• /
• 2013

Recent major post-hurricane damage assessments in the United States have reported that the most common damages result from the loss of building roof coverings and subsequent wind driven rain intrusion. In an effort to look further into this problem, this paper presents a full-scale (Wall of Wind --WoW--) investigation of external and underneath wind pressures on roof tiles installed on a low-rise building model with various gable roofs. The optimal dimensions for the low-rise building that was tested with the WOW are 2.74 m (9 ft) long, 2.13 m (7 ft) wide, and 2.13 m (7 ft) high. The building is tested with interchangeable gable roofs at three different slopes (2:12; 5:12 and 7:12). The field tiles of these gable roofs are considered with three different tile profiles namely high (HP), medium (MP), and low profiles (LP) in accordance with Florida practice. For the ridge, two different types namely rounded and three-sided tiles were considered. The effect of weather block on the "underneath" pressure that develops between the tiles and the roof deck was also examined. These tests revealed the following: high pressure coefficients for the ridge tile compared to the field tiles, including those located at the corners; considerably higher pressure on the gable end ridge tiles compared to ridge tiles at the middle of the ridge line; and marginally higher pressure on barrel type tiles compared to the three-sided ridge tiles. The weather blocking of clay tiles, while useful in preventing water intrusion, it doesn't have significant effect on the wind loads of the field tiles. The case with weather blocking produces positive mean underneath pressure on the field tiles on the windward side thus reducing the net pressures on the windward surface of the roof. On the leeward side, reductions in net pressure to a non-significant level were observed due to the opposite direction of the internal and external pressures. The effect of the weather blocking on the external pressure on the ridge tile was negligible.

• Applied Chemistry for Engineering
• /
• v.16 no.6
• /
• pp.794-799
• /
• 2005

With the quantitative growth of the petroleum industry, the pipe facilities that connect each process increased significantly and the corresponding maintenance and repair costs of the pipe facilities increased as well. The diagnosis techniques to check a pipe efficiency while in operation are few in Korea, but in the advanced countries the pipe diagnosis using gramma-ray source was on-going research since 1960's. In this study, field experiments were performed to analyze the reasons for abnormal operation of the pipe connected to a distillation tower, and the degree of abnormality was estimated using a sealed gamma-ray source ($^{137}Cs$). Gamma radiation counts were measured by a detector (NaI) positioned outside the pipe-wall diametrically opposite to the gamma source. The results showed that a gas zone section's distribution pattern was different from the pattern of nearby fluid in a pipe. Th diagnosis technique using a gamma radiation source was proved to be an effective and reliable method, offering the information on the fluid distribution in pipe.

• Food Science of Animal Resources
• /
• v.29 no.6
• /
• pp.695-701
• /
• 2009

This study was performed to evaluate the effectiveness of biological critical control points using the genetic profile of Escherichia coli isolates from pork cutting plants. Samples were collected from carcasses, equipment (knife, table, glove, transport belt, boning and skinning machine), the environment (wall and floor), and meat cuts during the cutting process from two plants. Pulsed-field gel electrophoresis (PFGE) was used to characterize the E. coli isolates. An identical genotype was detected from the carcasses, equipment, environment, and final meat cuts, and showed that the incoming carcasses, which were contaminated during transportation from slaughterhouses, were a major source of E. coli that was spread throughout processing. Also, consistent cross-contamination due to improper cleaning and disinfection procedures was another possibility. As a result, incoming carcasses and cleaning procedures should be considered critical control points in pork cutting plants, since a heating step is not used to inactivate microorganisms. Furthermore, the high rate (59.6%) of E. coli isolation indicates E. coli can be a good indicator in livestock processing plants even though it has genetic diversity.

• Restorative Dentistry and Endodontics
• /
• v.23 no.1
• /
• pp.477-486
• /
• 1998

Recently the development of rotary instrument makes it possible that in root canal treatment operator saves much more time, maintans original curved canal shape and easily prepares continuous tapered root canal. The purpose of this experiment was to examine the smoothness of the internal surface of prepared root canal and the effectiveness of debridement in prepared root canal by SEM for the comparison of hand and Ni-Ti rotary instrument. 25 extracted human teeth were access opened and # 10 K-type file was introduced into canal until it was appeared at the apical foramen. The working length was established by subtracting 0.5mm from this measurement. Group 1. The root canal preparation was done to # 30 with working length and then step-back until # 45 with K-Flexofile (Maillefer, Swiss). Group 2. Root canal preparation was done by Naviflex Ni-Ti file (Brasseler, USA) as the same technique with group 1. Group 3. Canal was prepared by Profile .04 (Maillefer, Swiss) taper until #30. Group 4. With use of Quantec (Tycom, USA) root canal was prepared from file number 1 to 8. In group 1 and 2, the root canal irrigant was NaOCl and the other groups, NaOCl and RC-prep (Premine Dental Products, USA) was used. The prepared teeth were notched with high-speed bur as bucco-lingual direction and fractured with chisel and mallet, then examined with SEM. Group 1 showed smooth internal surface. There were scratches mainly to the axial direction. Group 2 showed similar characteristics to those in group 1. Group 3 showed more smoother and linear cutting surface with bised scratches. Group 4 has the almost same characteristics group 3 and there was no difference in the file design. Ni-Ti rotary root canal instrument prepare the dentinal wall more smoother than hand instrument. The effectiveness of debridement was not fully affected by file design. The isthmus area and accessory canals of the root canal system were not prepared in any group. According to the result, hand and rotary type instrumentation techniques were effective in removal of major amount of tissue from root canal but it was not complete. In the direction of cutting movement there was difference between them.

• Journal of Digestive Cancer Research
• /
• v.6 no.1
• /
• pp.25-31
• /
• 2018

Background: In Korea, stomach cancer is the second most common malignancy and the third leading cause of cancer-related deaths. the time of diagnosis is very important for treatment so early detection and surgery are currently considered the mainstay of treatment, when diagnosed advanced with tumor extension through the gastric wall and direct extension into other organs, with metastatic involvement. Recently, new drugs, drug combinations, and multimodal approaches have been used to treat this disease and In cancers over expressing or amplifying HER2, the combination of cisplatin-fluoropyrimidine-trastuzumab is considered to be the treatment of reference. but At present, the choice of treatment schedule for HER2-negative tumors is based on the medical institution's preferences and adverse effects profile. The aim of this study was to evaluate the effectiveness and safety of using FOLFOX regimen as a first-line therapy or a salvage therapy in the patients with HER2-negative advanced or metastatic gastric cancer. Methods: We retrospective reviewed the patient medical record from March 2012 to July 2017. This study evaluated 113 patients. Sixty-eight patients were treated with the FOLFOX regimen for the first time (first-line group) and 45 patients were treated with the FOLFOX regimen as a second (35 patients) or third (10 patients) chemotherapy (salvage group). Results: In the first-line group, the response rate was 54.9%. In the salvage therapy group, the response rate was 24.4% and The difference was statistically significant (p=0.205). The median TTP of the first-line group was 10.7 months (95% confidence interval [95% CI], 7.8-13.7 months) and that of salvage line group was 6.1 months (95% CI, 3.8-8.4 months). The median OS of the first-line group was 15.8 months (95% CI, 12.7-18.9 months) and that of the salvage therapy group was 10.2 months (95% CI, 8.2-11.9 months). drug toxicity was similar andtolerable between two groups. Conclusion: In patients with unresctable metastatic gastric cancer, after failing to respond to first-line therapy, most patients have no alternative other than second-line therapy because the disease is highly progressive. if the performance status of the patient is good enough to be eligible to treatments beyond best supportive care. FOLFOX regimen can be a considerable therapeutic option for salvage treatment.

• The Korean Journal of Nuclear Medicine
• /
• v.39 no.6
• /
• pp.473-480
• /
• 2005

Purpose: Adenosine myocardial perfusion SPECT has proven to be useful in the detection of coronary artery disease, in the follow up the success of various therapeutic regimens and in assessing the prognosis of coronary artery disease. The purpose of this study is to define the reproducibility of myocardial perfusion SPECT using adenosine stress testing between two consecutive Tc-99m sestaMIBI (MIBI) SPECT studies in the same subjects. Methods: Thirty patients suspected of coronary artery disease in stable condition underwent sequential Tc-99m MIBI SPECT studies using intravenous adenosine. Gamma camera, acquisition and processing protocols used for the two tests were identical and no invasive procedures were performed between two tests. Mean interval between two tests were 4.1 days (range: 2-11 days). The left ventricular wall was divided into na segments and the degree of myocardial tracer uptake was graded with four-point scoring system by visual analysis. Images were interpretated by two independent nuclear medicine physicians and consensus was taken for final decision, if segmental score was not agreeable. Results: Hemodynamic responses to adenosine were not different between two consecutive studies. There were no serious side effects to stop infusion of adenosine and side effects profile was not different. When myocardial uptake was divided into normal and abnormal uptake, 481 of 540 segments were concordant (agreement rate 89%, Kappa index 0.74). With four-grade storing system, exact agreement was 81.3% (439 of 540 segments, tau b=0.73). One and two-grade differences were observed in 97 segments (18%) and 4 segments (0.7%) respectively, but three-grade difference was not observed in any segment. Extent and severity scores were not different between two studios. The extent and severity scores of the perfusion defect revealed excellent positive correlation between two test (r value for percentage extent and severity score is 0.982 and 0.965, p<0.001) Conclusion: Hemodynamic responses and side effects profile were not different between two consecutive adenosine stress tests in the same subjects. Adenosine Tc-99m sestaMIBI SPECT is highly reproducible, and could be used to assess temporal changes in myocardial perfusion in individual patients.