• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2381-2386
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• 2000

Surface replication is playing an important role in the assessment of creep damage and remaining life of high temperature components. As the replication procedures, however, have not been standardized in domestic industry, its standardization is proposed in this study. For this purpose, the 2.25Cr-IMo steel was heat treated(5 min at 1,300 0C and oil quenched) to produce a simulated HAZ microstructure, and crept in air at 575 0C and under 120 MPa to produce artificial cavities. Then, the effect of surface preparation procedures on the quality of replicas was investigated using this sample. As a result, it was demonstrated that the presence of cavities may be observed readily or missed depending on the surface preparation procedures followed. Therefore it is essential to repeat three polishing/etching cycles at least in order to reveal cavitation damage accurately, even though it may be tedious or time-consuming.

• International Journal of Automotive Technology
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• v.8 no.1
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• pp.67-73
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• 2007

This study analyzes the interior noise that is generated during acceleration of a passenger car in terms of car body structure and panel contribution. According to the transfer method, interior noise is classified into structure-borne noise and air-borne noise. Structure-borne noise is generated when the engine's vibration energy, an excitation source, is transferred to the car body through the engine mount and the driving system and the panel of the car body vibrates. When structure-borne noise resonates in the acoustic cavity of the car interior, acute booming noise is generated. This study describes plans for improving the car body structure and the panel form through a cause analysis of frequency ranges where the sound pressure level of the rear seat relative to the front seat is high. To this end, an analysis of the correlation between body attachment stiffness and acoustic sensitivity as well as a panel sensitive component analysis were conducted through a structural sound field coupled analysis. Through this study, via research on improving the car body structure in terms of reducing rear seat noise, stable performance improvement and light weight design before the proto-car stage can be realized. Reduction of the development period and test car stage is also anticipated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.2 s.95
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• pp.161-168
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• 2005

The absorbing material is mostly used to changing the acoustic energy to the heat energy in the passive control, and that consists of the porous media. That controls an air borne noise while the stiffened plates, damping material and additional mass control a structure borne noise. The additional mass can decrease the sound by mass effect and shift of natural frequency, and damping material can decrease the sound by damping effect. The passive acoustic control using these kinds of control materials has an advantage that is possible to control the acoustic in the wide frequency band and the whole space at a price as compared with the active control using the various electronic circuit and actuator. But the space efficiency decreased and the control ability isn't up to the active control. So it is necessary to maximize the control ability in the specific frequency to raise the capacity of passive control minimizing the diminution of space efficiency such an active control. Therefore, the characteristics of control materials and the optimum layout of control materials that attached to the boundary of structure-acoustic coupled cavity were studied using sequential optimization on this study.

• Food Science and Biotechnology
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• v.14 no.5
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• pp.621-627
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• 2005

Halitosis is mainly caused by the presence of volatile sulfur-containing compounds (VSC's) produced by proteolytic periodontopathic bacteria in the oral cavity. Various mouth-rinses have been offered on the market as solutions to reduce halitosis. The aim of this study was to find a potent substance for the prevention of halitosis. The halitosis prevention substance (HPS) from cumin seed powder was purified by solvent extraction, silica gel column chromatography and preparative TLC to yield an oil phase (0.98%). Instrumental analysis such as FT-IR, $^1H$-NMR and $^{13}C$-NMR showed that HPS contained an -OH group, -HC=CH-, -COO-, and long chain acyl group. HPS was therefore determined to be 2-hydroxyethyl-${\beta}$-undecenate. HPS inhibited the growth of Fusobacterium nucleatum and Porphyromonas gingivalis, by 72.44% and 64.37% at $1{\times}10^{-2}\;M$, and by 99.85% and 91.62% at $5\;{\times}\;10^{-2}\;M$, respectively. It also inhibited the activity of L-methionine-${\alpha}$-deamino-${\gamma}$-mercaptomethane-lyase (METase), which was produced by oral microbes. Furthermore, the VSC production by oral microbes in the human mouth air decreased with increasing HPS concentration. These results suggested that HPS from cumin seed is an efficient halitosis prevention agent.

• Journal of Chest Surgery
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• v.24 no.10
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• pp.1011-1018
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• 1991

From September, 1985 to March, 1991, 33 patients under went thoracotomy for treatment of pulmonary aspergilloma with Pulmonary tuberculosis on the department of Thoracic and Cardiovascular Surgery, National Kongju Hospital. 1. There were 25 male and 8 female patients ranging from 19 to 57 years old [mean age, 36.2 years]. 2. Hemoptysis was the most common symptom [recurrent minor hemoptysis: 24cases, severe hemoptysis [200cc /day]: 4 cases, massive hemoptysis [600/day]: 4 cases]. 3. In the chest X-ray films, intracavitary fungus balls [air meniscus sign] were noted in 20 cases [61%] and upper lobe involvements were 29 cases [88%]. 4. All cases had a history of treatment with antituberculosis drugs under diagnosis of pulmonary tuberculosis for an average of 10 years and 2 months. 5. The most common indication for operation was hemoptysis [32 cases] - hemoptysis with total destroyed lung or lobe: 12cases, hemoptysis with open AFB [t-] cavity: 6cases, recurrent or massive hemoptysis: 14 cases. 6. The operative procedures was as follows - - - lobectomy . 16 cases, pneumonectomy: 8 cases, bilobectomy, segmentectomy, cavernoplasty and lobectomy with segmentectomy: each 2 cases, lobectomy with cavernoplasty: 1 case. 7. 6 complications appeared postoperatively which included empyema with BPF [2 cases], empyema [2 cases] and wound infection [2 cases]. In conclusion, surgical resection is the treatment of choice in the management of pulmonary aspergilloma associated pulmonary tuberculosis.

• Korean Journal of Animal Reproduction
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• v.8 no.1
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• pp.29-35
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• 1984

These experiments were carried out to obtain basic information necessary for in vitro culture of aggregated mouse embryos. Inbred ICR mice were used to obtain embryos. The zona pellucida was removed by placing the embryos in Whittingham's medium containing 0.5% protease for about 5-10minutes at 37$^{\circ}C$. Total 263 pairs of 2-, 4- and 8-cell zona free mouse embryos were subjected to aggregation by physical pressure and cultured in Whittingham's medium under the gas phase of 5% CO2 in air at 37$^{\circ}C$ for 24 to 60 hours. The results obtained in these experiments were summarized as follows: 1. Time needed for fusion of 2-, 4- and 8-cell embryos were 0-3, 0-3 and 0-3 hours, respectively and average time needed for in vitro development of 2-, 4- and 8-cell embryos after aggregation to morula and blastocyst were 42, 30 and 13.5 hours, and 51, 39 and 27 hours, respectively. 2. Of total 263 pairs of naked embryos, 227 were firmly aggregated together and the rats of aggregation in 2-, 4- and 8-cell embryos were 71.8, 88.3 and 97.0%, respectively. 3. The rates of aggregated pairs which obtained from 2-, 4- and 8-cell embryos developed to morula were 96.7, 95.6 and 96.9%, respectively, and embryos developed to blastocysts were 88.5, 89.7 and 90.8%, respectively. 4. Conspicuous differences in size of volume and inner cell masses between single and double blastocysts were observed. Although a single blastocolic cavity was formed in most double blastocysts, several formed two distinct cavities from the very beginning.

• KIEAE Journal
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• v.8 no.1
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• pp.11-18
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• 2008

The purpose of this study is to analyze application methods and structural characteristics of each element of environment-friendly European housing through classification of skin types. The results of the study are following. 1) The skins are classified by three types; single skin with multi layers, double skin with single layer and double skin with multi layers. 2) Most single skins with multi-layer are composed with wooden louvers, sun blinds and insulating windows. There are introduction of atrium and balcony, and variation sectional space composition according to cases. 3) There are two types of double skins; to put cavity between inner skin and outer skin and more extensional spaces such as balconies, corridors and stair halls. Solar walls and mechanical ventilators are often introduced to double skins with multi-layer. 4) The functions of the latest environment-friendly skins are vary from controllers and buffers of indoor environmental elements such as temperature, light, air and sound to equipments to perform essential functions to efficiently operate HVAC systems.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.4
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• pp.894-903
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• 2014

Insertion loss prediction of large acoustical enclosures using Statistical Energy Analysis (SEA) method is presented. The SEA model consists of three elements: sound field inside the enclosure, vibration energy of the enclosure panel, and sound field outside the enclosure. It is assumed that the space surrounding the enclosure is sufficiently large so that there is no energy flow from the outside to the wall panel or to air cavity inside the enclosure. The comparison of the predicted insertion loss to the measured data for typical large acoustical enclosures shows good agreements. It is found that if the critical frequency of the wall panel falls above the frequency region of interest, insertion loss is dominated by the sound transmission loss of the wall panel and averaged sound absorption coefficient inside the enclosure. However, if the critical frequency of the wall panel falls into the frequency region of interest, acoustic power from the sound radiation by the wall panel must be added to the acoustic power from transmission through the panel.

• Transactions of Materials Processing
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• v.22 no.4
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• pp.183-188
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• 2013

Scroll compressors are widely used in air conditioning systems and in automobiles due to their low pressure loss, minimal vibrations, and light-weight. Open-die forging with back pressure is used to forge the rotating scroll, and it requires special care since the forging die can be severely damaged at the fixed end of the spiral cavity similar to a fracture of a cantilever beam. To overcome the inevitable weakness of the forging die due to such damage, an innovative design is necessary. In this study, structural analysis using the finite element method was conducted to determine the reason for the fracture of the forging die. A novel design to avoid stress concentrations and vertical deflection, causing serious damage to the die, is suggested.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.741-747
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• 2002

In this paper, NRD guide band pass filter with newly designed inductive iris structure is proposed and analyzed with its test results. In case of common NRD guide filter with air gap coupled structure, it was not easy to fabricate and process or each NRD guide dielectric resonator blocks using PTFE. However, in this our research, each dielectric resonator fabricated in a single NRD guide is coupled with inductive iris located on metal plates. The structure is suitable for mass production of a precise and reliable millimeter-wave filter applications. As a result of measurements, designed NRD guide inductive iris filter has superior performance. The pass band is 38.66~39.06 MHz with 400 MHz bandwidth, insertion loss is about 1.4 dB and return loss is below -18 dB.