• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06a
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• pp.662-667
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• 1994

This paper presents the design and construction details of a soundproof enclosure for housing 20 KVA diesel generator-set. As the generator had to be installed close to the hospital building, it was desirable to reduce the transmission of noise by housing the generator in such an enclosure. The diesel engine being an air cooled one, it was essential to supply fresh air into the enclosure for its cooling. Forced inflow of air is provided through an inlet duct located in such a way that the incoming fresh air is thrown close to the inlet of cooling fan of the engine. The high velocity air stream, which heats up while passing over the engine head, escapes to the atmosphere through a rectangular outlet duct with enlarges inlet that receives hot air from the engine. The air ducts were designed specially and have been provided with acoustic lining for sound absorption. The masonary enclosure has been provided with double glazed fixed windows and double doors. The exhaust pipe of the engine fitted with a muffler has been taken out through the enclosure wall facing away from the hospital. Acoustic performance studies conducted in terms of attenuation provided by the enclosure at different frequencies have also been presented and discussed. The noise control measures adopted for building the sound-proof enclosure have been found to be quite effective as the noise levels inside the hospital building are now within the acceptable limits.

• Journal of Trauma and Injury
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• v.34 no.3
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• pp.203-207
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• 2021

Penetrating brain injury caused by a nail gun is an uncommon clinical scenario reported in the literature. A 36-year-old male presented with a nail that had penetrated through the occipital bone. He was alert and neurologically intact except for visual disturbance. Computed tomography (CT) of the brain showed the nail lodged at the occipital lobe and the parietal lobe, with minimal intracerebral hemorrhage. The nail was placed in the occipital lobe close to the superior sagittal sinus. We removed the nail with craniotomy since the entrance of the nail was close to the superior sagittal sinus. There were no newly developed neurological deficits postoperatively. Immediate postoperative CT showed no newly developed lesions. The patient recovered well without any significant complications. Two weeks postoperatively, magnetic resonance imaging showed no remarkable lesions. The visual disturbance was followed up at the outpatient department. To summarize, we report a rare case of penetrating head injury by a nail gun and discuss relevant aspects of the clinical management.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.48 no.4
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• pp.232-236
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• 2022

A ranula is a pseudocyst that originates from the sublingual gland after trauma. Acute cases of ranulas that progress rapidly and cause respiratory distress are rare. Holoprosencephaly is a complex brain malformation caused by incomplete cleavage of the prosencephalon. Children with holoprosencephaly may experience upper airway obstruction due to the associated dentoalveolar malformations and oromotor dysfunctions. We present the case of an eight-year-old female patient with holoprosencephaly and a plunging ranula that manifested as an acute course due to difficult airway management. She required gastrostomy for oromotor dysfunctions related to feeding and swallowing and difficulty managing oral secretions. The sublingual gland and ranula were removed under general anesthesia. Postoperatively, urgent reintubation and close monitoring in the intensive care unit were required due to upper airway obstruction. We successfully managed the patient with close cooperation of a pediatrician and an anesthetist, and no recurrence was observed at the one-year follow-up. A ranula can be caused by trauma to the floor of the mouth in association with lingually inclined mandibular teeth, a type of dentoalveolar compensation seen in maxillary hypoplasia associated with holoprosencephaly. Careful consideration is needed in such cases since airway management can be difficult due to postoperative swelling and oromotor dysfunctions.

• Computers and Concrete
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• v.33 no.6
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• pp.671-688
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• 2024

The modeling efficiency of concrete meso-models close to real concrete is one of the important issues that limit the accuracy of mechanical simulation. In order to improve the modeling efficiency and the closeness of the numerical aggregate shape to the real aggregate, this paper proposes a method for generating a two-dimensional concrete meso-model based on pixel matrix and skeleton theory. First, initial concrete model (a container for placing aggregate) is generated using pixel matrix. Then, the skeleton curve of the residual space that is the model after excluding the existing aggregate is obtained using a thinning algorithm. Finally, the final model is obtained by placing the aggregate according to the curve branching points. Compared with the traditional Monte Carlo placement method, the proposed method greatly reduces the number of overlaps between aggregates by up to 95%, and the placement efficiency does not significantly decrease with increasing aggregate content. The model developed is close to the actual concrete experiments in terms of aggregate gradation, aspect ratio, asymmetry, concavity and convexity, and old-new mortar ratio, cracking form, and stress-strain curve. In addition, the cracking loss process of concrete under uniaxial compression was explained at the mesoscale.

• Journal of the Korean Society of School Health
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• v.10 no.2
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• pp.241-257
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• 1997

This study identifies a basic framework to analyze specific experiences of examinees so that which nurses are better able to understand reactions of examinees and, further, to provide better nursing treatments to them. This study follows Strauss & Corbin's analysis tool (1990). This basic framework identifies the specific mental reactions in a process away from the "being tightened" state. The main factors explaining this process include the 28 following variables : anxiety, being burdened, being suppressed, lack of agency, being suffocated, term pressure, expectation pressure, grade pressure, firmness, feebleness, helping others, being disturbed, watching others, off ficiousness, staightening on, depending on, getting along with, getting out of, shooting out, giving up, being alone, devoting, bracing up, being industrious, being harassed, being distressed, troubles, and quiting. Twelve variables are factored from the above factors which include pressure, being tighened, terms, expectations, grades, will, friends, family, open-minded confrontation, close-minded confrontation, pursuing, and wandering around. The Examinees' state of being tightened is first developed, watched by others, and finally resolved causing students either to pursue (positive reactions) or to wander around (negative reactions). Based on the theoretical framework, the following sixteen hypotheses are developed : 1. Students are less tightened in the first term. 2. Students are more tightened in the second term. 3. Students with higher grades feel less tightened. 4. Students with lower grades feel more tightened. 5. Students with higher expectations feel more tightened. 6. Students with lower expectations feel less tightened. 7. Students who are less tightened confront open-mindedly. 8. Students who are higher tightened confront close-mindedly. 9. Students with a strong will confront open-mindedly. 10. Students with a weak will confront close-mindedly. 11. Students who have more sincere friends confront open-mindedly. 12. Students who have less sincere frieds confront close-mindedly. 13. Students with family support confront open-mindedly. 14. Students with little family support confront close-mindedly. 15. Students confronting open-mindedly pursue. 16. Students confronting close-mindedly wander. We identify the following four relations from the data analysis : 1. Students with average grades in their first term are more tightened from high expectations and have a tendency to wander if they have less supporting families even if they also have a strong will and sincere friends. 2. Students with low grades in their second term are less tighened because of low expectations and have a tendency to wander if they have a weak will and few sincere friends even if they have strong family support. 3. Students with high grades in their second term are more tightened with high expectations and have a tendency to pursue confrontations open-mindedly if they have supporting families and a strong will even if they have few sincere friends. 4. Students with average grades in their first term are less tightened from fewer expectations and have a tendency to pursue confrontations open-mindedly when they have more supporting families and sincere friends even if they have a weak will. A Student's degree of being tightened are affected by grades, terms, and expectations. Being tightened is resolved positively or negatively based on will, friends, and family. We conclude that will, family support, and sincere friends cause students to confront "being tightened" open-mindedly. We also conclude that practical nursing for students who are tightened have to focus on creating environments in which students are able to confront open-mindedly.

• Archives of Plastic Surgery
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• v.36 no.3
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• pp.344-347
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• 2009

Purpose: Malignant soft tissue tumors, known as sarcomas, are well known to be locally aggressive, frequently metastatic, and highly recurrent. In other hands, intermediate soft tissue tumors often recur locally with adjacent tissue infiltration so the clinical management is difficult as sarcoma. In the present study, we evaluate the clinical course of the intermediate soft tissue tumors and consider the management plan for those. Methods: From March, 1998 to April 2008, total 3 patients of intermediate soft tissue tumors underwent operations. A patient with fibrohistiocytic neoplasm, a free flap reconstruction was performed, and he underwent several more operations because of recurrences. Other patients with desmoids - type fibromatosis showed local invasion and adhesion, and one of them underwent reoperation due to local recurrence. Results: 2 of 3 patients underwent recurrences of tumors and reoperations were performed. In another patient with no recurrence, follow-up period was just 5 months, so there may be recurrence of tumor in long term follow-up. Conclusion: The clinical course of intermediate soft tissue tumors shows high recurrence rate. So clinically, intermediate soft tissue tumors should be considered as sarcomas. The successful management requires wide resection, carefully planned reconstruction, and close follow up with radiologic evaluation.

• Transactions of Materials Processing
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• v.18 no.6
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• pp.465-470
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• 2009

The frictional behaviors of Cermets/Cr-Ceramics and Cu-Al coatings of piston ring were investigated. Friction tests were carried out by pin-on-disk test and materials properties of coating layer were analyzed by nano indentation tester. The effect of surface roughness of cylinder liner on the friction coefficient was analyzed. This study provided tribological data of hard and soft piston ring coatings against cylinder liner. The surface roughness does exert an influence on the average friction coefficient, with smoother surfaces generally yielding lower friction coefficients. In case of hard-coating, the scratch depth, width and pile-up height had close relationship with hardness. So the scratch width, depth and pile-up height increases with decreasing friction coefficient. But in case of soft-coating, the friction coefficients are strongly dependent on the morphological characteristics such as, scratch depth, width, pile-up height and elastic modulus.

• Textile Coloration and Finishing
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• v.7 no.4
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• pp.33-38
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• 1995

In resist-discharge printing of cotton fabrics with reactive/reactive dyes the effects of intermediate drying on the white and the colored resist-dischargeabilities were studied. From the results of resist-discharge printing in case of 75% pick up, it was found that the most effective condition of intermediate drying which could at once prevent bleeding and improve the resist-dischargeability was 11$0^{\circ}C$ x 1min. The drying condition of 10$0^{\circ}C$ x 2min or 12$0^{\circ}C$ x 1min can be also recommended. It is important to pay close attention to the intermediate drying temperature and time. Because in case of 75% pick up when drying was carried on at 11$0^{\circ}C$ or 12$0^{\circ}C$ for more than 1 minute the resist-dischargeability was greatly lowerd by the fast fixation of ground color caused by high temperature, and in case of 100 % pick up the insufficient drying of ground color caused the resist-dischargeability to lower with giving rise to various troubles such as bleeding and smearing.

• International Journal of Advanced Culture Technology
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• v.12 no.1
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• pp.276-280
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• 2024

Recently, many policies and fairs have been made in relation to start-ups. In addition, various start-up education for prospective start-ups is being conducted in various ways. Therefore, these days, the number of prospective start-ups who receive such information and start-up education is increasing. Nevertheless, more and more start-ups are still unsuccessful and close their businesses within months or years. In particular, start-ups who continue to maintain their start-ups also see the unfortunate reality of start-ups that find other jobs in various support systems and related policies and relationships that they cannot quit even if they want to. In this study, based on previous studies, factors for satisfaction with entrepreneurship education will be set and a questionnaire will be conducted for prospective entrepreneurs who have completed education at a startup education center in Seoul. The survey results are intended to verify their reliability and validity through empirical analysis. The SPSS statistical package will be used for analysis, and a total of 200 copies of the questionnaire will be distributed and collected. In this study, it was confirmed that the higher the satisfaction with entrepreneurship education, the better the successful entrepreneurship. In addition, I think that further developing various policies or detailed curriculums for entrepreneurship education will be of great help to prospective entrepreneurs taking entrepreneurship education.

• Journal of Intelligence and Information Systems
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• v.26 no.1
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• pp.119-133
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• 2020

Fama asserted that in an efficient market, we can't make a trading rule that consistently outperforms the average stock market returns. This study aims to suggest a machine learning algorithm to improve the trading performance of an intraday short volatility strategy applying asymmetric volatility spillover effect, and analyze its trading performance improvement. Generally stock market volatility has a negative relation with stock market return and the Korean stock market volatility is influenced by the US stock market volatility. This volatility spillover effect is asymmetric. The asymmetric volatility spillover effect refers to the phenomenon that the US stock market volatility up and down differently influence the next day's volatility of the Korean stock market. We collected the S&P 500 index, VIX, KOSPI 200 index, and V-KOSPI 200 from 2008 to 2018. We found the negative relation between the S&P 500 and VIX, and the KOSPI 200 and V-KOSPI 200. We also documented the strong volatility spillover effect from the VIX to the V-KOSPI 200. Interestingly, the asymmetric volatility spillover was also found. Whereas the VIX up is fully reflected in the opening volatility of the V-KOSPI 200, the VIX down influences partially in the opening volatility and its influence lasts to the Korean market close. If the stock market is efficient, there is no reason why there exists the asymmetric volatility spillover effect. It is a counter example of the efficient market hypothesis. To utilize this type of anomalous volatility spillover pattern, we analyzed the intraday volatility selling strategy. This strategy sells short the Korean volatility market in the morning after the US stock market volatility closes down and takes no position in the volatility market after the VIX closes up. It produced profit every year between 2008 and 2018 and the percent profitable is 68%. The trading performance showed the higher average annual return of 129% relative to the benchmark average annual return of 33%. The maximum draw down, MDD, is -41%, which is lower than that of benchmark -101%. The Sharpe ratio 0.32 of SVS strategy is much greater than the Sharpe ratio 0.08 of the Benchmark strategy. The Sharpe ratio simultaneously considers return and risk and is calculated as return divided by risk. Therefore, high Sharpe ratio means high performance when comparing different strategies with different risk and return structure. Real world trading gives rise to the trading costs including brokerage cost and slippage cost. When the trading cost is considered, the performance difference between 76% and -10% average annual returns becomes clear. To improve the performance of the suggested volatility trading strategy, we used the well-known SVM algorithm. Input variables include the VIX close to close return at day t-1, the VIX open to close return at day t-1, the VK open return at day t, and output is the up and down classification of the VK open to close return at day t. The training period is from 2008 to 2014 and the testing period is from 2015 to 2018. The kernel functions are linear function, radial basis function, and polynomial function. We suggested the modified-short volatility strategy that sells the VK in the morning when the SVM output is Down and takes no position when the SVM output is Up. The trading performance was remarkably improved. The 5-year testing period trading results of the m-SVS strategy showed very high profit and low risk relative to the benchmark SVS strategy. The annual return of the m-SVS strategy is 123% and it is higher than that of SVS strategy. The risk factor, MDD, was also significantly improved from -41% to -29%.