• Earthquakes and Structures
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• v.26 no.5
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• pp.363-382
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• 2024

In India's north-eastern region, low-strength autoclaved aerated concrete (AAC) blocks are widely used for constructing masonry structures, making them susceptible to lateral forces due to their low tensile and shear strengths and brittleness nature. The absence of earthquake-resistant attributes further compromises their resilience during seismic events. An economically viable solution to enhance the structural integrity of these masonry structures involves integrating steel wire mesh within the masonry mortar joints. This study investigates the in-plane shear behaviour of AAC masonry by employing two approaches: incorporating steel wire mesh within the masonry bed joint "BJ" and the masonry bed and head joint "BHJ". These approaches aim to augment strength and ductility, potentially serving as earthquake-resistant attributes in masonry structures. Three distinct variations of steel wire mesh and three reinforcing arrangements, i.e. (-), (L) and (Z) arrangement were employed to reinforce the two approaches. The test result reveals a significant enhancement in structural performance upon inclusion of steel wire mesh in both reinforcing approaches, with the "BHJ" approach outperforming the "BJ" approach and the unreinforced masonry, along with increase in capacity as the wire mesh size increases. Furthermore, the effectiveness of the reinforcing arrangement is ranked with the (Z) arrangement showing the largest performance, followed by the (L) and (-) arrangement.

• Korean Journal of Ecology and Environment
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• v.43 no.2
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• pp.190-198
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• 2010

This study was conducted to examine the effects of dams on benthic macroinvertebrate communities in Korean streams and rivers. Four low-head dams and three large dams were studied throughout South Korea. Sampling was taken at immediately upper (impoundment), lower (riffle area), and control (riffle area) sites from the dams during 2004-2007. The upper sites, of which substrate heterogeneity and velocity were relatively low, showed a lower degree of species richness, density, and diversity indices, which is very different from the lower and control sites. Heavily polluted streams showed a lesser degree of community differences between the upper and lower sites. In the large dams, the upper and lower sites showed very low values of species diversity indices and very high values of dominance indices compared to the control sites. In the low-head dams, however, the difference of degree of the values was relatively smaller. Compositions of the functional feeding groups and the habitat orientation groups were relatively simpler at the upper sites than at the lower sites and the degree of difference was greater in the large dams. Species richness and community indices of benthic macroinvertebrates were more significantly affected by habitat characteristics than water quality at the upper sites; however, those were more significantly related with water quality at the lower sites. In conclusion, large and low-head dams could simplify stream habitats particularly at the upper sites (impoundment), and they negatively affected on the benthic macroinvertebrate communities inhabited the habitats. The impact was larger in the large dams than in the low-head dams.

• Fire Science and Engineering
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• v.31 no.3
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• pp.54-62
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• 2017

The aim of this study is to find out the water spray features of in-rack sprinklers for rack storage. This study conducted cold water flow test, measurement of spray angle and densities by angles for sprinkler head manufactured by a Korean company and a U.S. company. Korean sprinkler head had a wide angle of water spary. The water spray angle of a U.S. sprinkler head was narrow compared to the Korean sprinkler. In comparison of the Korean head with U.S. head of the same K80, the Korean head can send water to parts that are difficult to directly spray, but the spraying density by angle was low. U.S. head can send more water than Korean head at a narrow angle. In conclusion, for flammable materials placed in two or more rows in a rack storage, a zigzag arrangement with face sprinklers will be effective.

• Korean Journal of Head & Neck Oncology
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• v.33 no.2
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• pp.89-93
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• 2017

Background. Ever since the first report of deltopectoral flap in pharyngo-esophageal reconstruction in 1965, various methods of flap reconstruction have been introduced, allowing surgical eradication of tumors that were once thought to be inoperable. Despite these advancement, many literatures emphasize distant metastasis and second primary malignancies as the most important factors that contribute to the low 5-year survival rate of the patients. Specific consensus about defining second primary cancer is still debatable, due to small number of reports regarding second primary tumors arising in flaps used for reconstruction of defects in the head and neck region. Case. We report a case of a 72-year-old male patient who, under the diagnosis of hypopharyngeal cancer, underwent total laryngectomy with partial pharyngectomy, extended right radical neck dissection with extended left lateral neck dissection, right hemithyroidectomy and radial forearm free flap reconstruction on June 16, 2003. After 37 cycles of radiation therapy, the patient exhibited no sign of recurrence. The patient revisited our department on June 14, 2016 with chief complaint of dysphagia that started two months before the visit. Radiologic studies and histology revealed squamous cell carcinoma in neopharynx, one that had been reconstructed with forearm free flap. Conclusion. Until now, only a handful of reports regarding patients with second primary cancer in reconstructed flaps have been described. Despite its rarity, diagnostic criteria for second primary cancer should always kept in consideration for patients with recurred tumor.

• Korean Journal of Head & Neck Oncology
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• v.25 no.2
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• pp.123-127
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• 2009

Objectives : The aim of this study was to investigate immunohistochemical expression of CK7, CK19, CK20, SMA and Ki-67 in Adenoid cystic carcinoma(ACC) of the Head and Neck. Material and Methods : Sixteen patients who were treated in Chungbuk National University Hospital from 1992 to 2004, were included in this study. Ten ACCs, 3 MECs, 1 Salivary duct carcinoma, 1 Adenocarcinoma(NOS), and 1 cacinoma ex pleomorphic adenoma were analyzed immunohistochemically for CK7, CK19, CK20, SMA, and Ki-67. Results : CK7 was expressed in 100% of the adenoid cystic carcinoma and 75% of the other tumors. CK19 was expressed in 75% of the adenoid cystic carcinoma and 100% of the other tumors. CK20 was not expressed in all tumors. SMA was expressed in 88.9% of the adenoid cystic carcinoma and not expressed in the other tumors. Ki-67 was expressed in low level in the adenoid cystic carcinoma. Conclusion : The Ki-67 index could explain the natural course of tumor. Immunohistochemistry of CK7, CK19, CK20, SMA and Ki-67 expression in Adenoid cystic carcinoma may provide useful information to diagnosis.

• Korean Journal of Head & Neck Oncology
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• v.15 no.2
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• pp.166-171
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• 1999

Background and Objectives: The aim of our study was to describe the appearance of recurrent and residual lesions in the head and neck tumors, and to evaluate the usefullness of CT and MRI. Materials and Methods: CT(n=42) and MRI(n=4) of 44 patients with recurrent head and neck tumors were reviewed retrospectively. Primary tumor sites were larynx/hypopharynx in 15, oral cavity/floor of mouth in 13, base of tongue/tonsil in 5, nasopharynx in 4, palate in 2, and others in 5 patients. Therapeutic modalities included sugery and radiotherapy in 23, radiotherapy in 11, surgery in 5, chemotherapy and radiotherapy in 4, and chemotherapy in 1 patient. Results: The patterns of tumor recurrence were nodal recurrence(n=17), primary tumor bed recurrence combined with nodal recurrence(n=12), primary tumor bed recurrence(n=10) and residual primary tumors(n=5). The most common appearance of residual/recurrent primary tumor on CT was focal or diffuse heterogenous mass with or without surrounding fat or muscle infiltration(25/27). On MRI, the recurrent lesions showed intermediate signal intensity on T1 weighted image and high signal intensity on T2 weighted image with heterogenous enhancement in the most cases(n=3). 38 out of 44 nodal recurrences(86%) which had been pathologically or clinically proved were more than 1 cm in diameter or contained central low density on CT scan. Conclusion: Although CT and MRI findings of recurrent and residual tumors of the head and neck were nonspecific, in the majority the lesions manifested as a mass at primary tumor bed and/or nodal disease including contralateral side of the neck. And CT and MRI are valuable for revealing above lesions.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.216-227
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• 2005

The head penetrations for control rod drive mechanism and instrumentation systems are installed at the reactor pressure vessel head of PWRs. Primary coolant water and the operating conditions of PWR plants can cause cracking of these nickel-based alloy through a process called primary water stress corrosion cracking (PWSCC). Inspection of the head penetrations to ensure the integrity of the head penetrations has been interested since reactor coolant leakages were found at U. S. reactors in 2000 and 2001. The complex geometry of the head penetrations and the very low echo amplitude from the fine, multiple flaws due to the nature of the see made it difficult to detect and size the flaws using conventional pulse-echo UT methods. Time-of-flight-diffraction technique, which utilizes the time difference between the flaw tips while pulse-echo does the flaw response amplitude from the flaw, has been selected for this inspection for it's best performance of the detection and sizing of the head penetration see flaws. This study defines the limits of the detectable and accurately sizable minimum flaw size which can be detected by the General TOFD and the Delta TOFD techniques for circumferentially and axially oriented flaws respectively. These results assures the reliability of the inspection techniques to detect and accurately size for various kind of flaws, and will also be utilized for the future development and qualifications of the TOFD techniques to enhance the detecting sensitivity and sizing accuracy of the flaws of the reactor head penetrations in nuclear power plants.

• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
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• v.61 no.12
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• pp.681-685
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• 2018

Background and Objectives This study was performed to evaluate the long-term effect of adenotonsillectomy on childhood growth by examining preoperative growth status and presenting symptoms. Subjects and Method One hundred and four patients who underwent adenotonsillectomy from January to December 2009 were enrolled in this study. Clinical data were collected from medical record reviews and through the administered questionnaire. We investigated symptoms and growth changes during 5 years following the surgery. Results The mean age of patients was $6.0{\pm}1.94$ years (range, 3-10), with the male to female ratio of 62:42. Pre-operative symptoms were significantly improved after the surgery. The mean pre-operative height and weight percentiles were $53.6{\pm}27.4$ and $59.6{\pm}29.2$ at initial evaluation, and $67.1{\pm}26.4$ and $59.6{\pm}28.6$ at 5 years post adenotonsillectomy (p<0.001, p=0.989), respectively. An increase in height percentile was more prominent in patients whose pre-operative height percentile was less than 50 compared to those with a percentile of 50 or more (p<0.001). Weight percentile was significantly increased in those with the pre-operative weight percentile of less than 50 and decreased in patients with a percentile of 50 or more. Conclusion Adenotonsillectomy has a positive effect on height growth in children with adenotonsillar hypertrophy, especially in patients whose height percentile is less than 50. Weight gain also can be expected in preoperative low-weight children.

• IEMEK Journal of Embedded Systems and Applications
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• v.17 no.4
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• pp.199-208
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• 2022

Korean is an agglutinative language, and one or more morphemes are combined to form a single word. Part-of-speech tagging method separates each morpheme from a word and attaches a part-of-speech tag. In this study, we propose a new Korean part-of-speech tagging method based on the Head-Tail tokenization technique that divides a word into a lexical morpheme part and a grammatical morpheme part without decomposing compound words. In this method, the Head-Tail is divided by the syllable boundary without restoring irregular deformation or abbreviated syllables. Korean part-of-speech tagger was implemented using the Head-Tail tokenization and deep learning technique. In order to solve the problem that a large number of complex tags are generated due to the segmented tags and the tagging accuracy is low, we reduced the number of tags to a complex tag composed of large classification tags, and as a result, we improved the tagging accuracy. The performance of the Head-Tail part-of-speech tagger was experimented by using BERT, syllable bigram, and subword bigram embedding, and both syllable bigram and subword bigram embedding showed improvement in performance compared to general BERT. Part-of-speech tagging was performed by integrating the Head-Tail tokenization model and the simplified part-of-speech tagging model, achieving 98.99% word unit accuracy and 99.08% token unit accuracy. As a result of the experiment, it was found that the performance of part-of-speech tagging improved when the maximum token length was limited to twice the number of words.

• Korean Journal of Head & Neck Oncology
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• v.22 no.1
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• pp.36-39
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• 2006

The Neurofibroma is a benign neoplasm originating from neural tissue such as Schwann cell, fibroblast and peripheral fibroblast, which rarely converts to malignancy. About 25-45% of neurofibroma are located in head and neck, and the most common sites are lateral cervical region and mouth. Because of its high vascularity and invasion to the adjacent organs, surgical resection may be confronted and limited, moreover large neurofibroma can cause large defect that needs various kinds of flap. The factors related to clinically suspected malignancy are painlessness, abrupt increase in size, firm fixation, and central ulceration, although the malignancy rate of neurofibroma is low. The complete resection was failed several times at local clinic, the patient was transferred to our hospital. We have successfully removed the retroauricular neurofibroma using transposition flap & free skin graft on its large defects.