• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.460-468
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• 2021

This study investigated the enhanced combustion efficiency of an "air-cooled combustion system" with single F.D. fan, and performed a numerical analysis for the operation and design conditions to increase the combustion efficiency. The combustion efficiency in an actual combustor was compared before and after the structure modification. Numerical analysis for application of a single fan revealed the difficulty of forming a turbulence for circular combustion conditions. This is because the supply ratio of combustion air supplied into 2 flow paths becomes irregular in the combustion furnace due to a change in friction force and pressure in each flow path. Subsequently, two methods of supplying air into the combustion furnace were analyzed numerically to obtain the optimal combustion conditions of an air-cooled combustion system. The first method involved injecting the preheated combustion air after a 180~360 degree rotation from the outer wall, whereas in the second method, the combustion air was injected into the combustion furnace in a tangential direction after primary heat exchange outside the combustion furnace, by applying a rotatable vane structure in the combustion furnace. Results reveal that application of a single F.D. fan to the air injection into a rotatable combustion furnace is desirable for optimization of the combustion conditions for applying a duct structure having a dual cooling wall for the cooling of the outer wall of the combustion furnace, and for maintaining perfect mixing in the combustion furnace. We therefore confirmed enhanced combustion efficiency by comparing the actual combustion efficiency before and after structure modification.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.2
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• pp.203-220
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• 1991

The purpose of this study was to investigate the changes of morphology and structure of bone tissue, caused by administration of high-dose hydrocortisone, elcatonin and cyclophosphamide. In order to carry out experiment, 60 four-week old Sprague-Dawley strain rats weighing about 107 gms were selected and divided into experimental group and control group. The experimental group was subdivided into three groups, assigned fifteen rats for each group, by the different drugs administered. Each experimental group was then categorized as follows: hydrocortisone 30㎎/㎏ b.w. with daily subcutaneous injection, elcatonin 20U/㎏ b.w. with daily subcutaneous injection, and cyclophosphamide 100㎎/㎏ b.w. with a single intraperitoneal injection. Fifteen rats were injected daily with 5㎖/㎏ b.w. of normal saline solution subcutaneously in control group. Rats in control group and experimental group were serially sacrificed on the 6th, the 15th and the 22nd day after injection of normal saline, hydrocortisone, elcatonin and cyclophosphamide, respectively. Being sacrificed, both sides of mandibular condyles were removed and fixed with 10% neutral formaline. The one side of mandibular condyles was radiographed with soft X-ray apparatus. Thereafter, the obtained radiographs were observed, and the bone density of condylar head and condylar neck regions was measured by use of transferring video-based digital radiograph. The other side was further decalcified and embedded in paraffin as usual manner, then sectioned and stained with hematoxylin and eosin, observed by light microscope. The obtained results were as follows: 1. Sclerotic changes with regularly increased trabecular pattern were seen throughout experimental periods in hydrocortisone group. Increased the number of trabecular pattern with irregularity and periodic striation on the periphery of condylar head region were appeared with lapse of time in elcatonin group. In cyclophosphamide group, irregular trabecular pattern and stippled radiopacities on mandibular condyle were observed with lapse of time. 2. The bone density of condylar head region was increased in hydrocortisone group, decreased in elcatonin group, and tended to be decreased in cyclophosphamide group, compared with that of control group according to the experimental periods. 3. The bone density of condylar neck region tended to be rather increased in hydrocortisone group, elcatonin group and cyclophosphamide group, depending on the experimental periods. 4. In microscopic studies, there were irregular trabecular bonds and osteoblastic activity in hydrocortisone group and elcatonin group throughout experimental periods, degenerative cartilage and trabecular bones in the 6th day and densely calcified trabecular bones in the 22nd day in cyclophosphamide group.

• Journal of Conservation Science
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• v.26 no.3
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• pp.277-294
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• 2010

The Seosanmaaesamjonbulsang (National Treasure No. 84) consists of light gray and coarse to mediumgrained biotite granite with partly developed pegmatite and quartz vein. The host rock is divided into dozens of rock blocks with various shape along irregular discontinuity plane. The evaluation results of discontinuity systems reveal that the host rock were exposed to instable sloping environments. Results of deterioration diagnosis show that the degree of damage has been made worse by physical weathering and surface discoloration laying stress on part that vertical and horizontal joints are massed. Generally, deterioration rate of the triad Buddha surface cover with 42.7%, however, the rate of physical weathering and surface discoloration are subdivided to 9.6% and 33.1%, respectively. Ultrasonic measurements indicate that the triad Buddha was reached highly weathered grade in general. And the rock material was weaken to show low velocity zone of 1,000m/s along irregular joint systems. Indoor and outdoor mean relative humidity of the shelter was recorded more than 70% during every season, and high frequency appears in high relative humidity range over 95%. Such environments seem to have produced dew condensation on the rock surface with rainfall and supply water, promoted physical, chemical and biological weathering along crack and joint, resulting in high permeation of water and percentage of water content. Therefore, it is judged that for scientific conservation of the triad Buddha it needs environment control through persistent preservation environment monitoring including water problem.

• Journal of Korean Public Health Nursing
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• v.12 no.1
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• pp.103-115
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• 1998

As the studies that smoking can be a major cause to various diseases have been made, many following researches on the outcome of stop-smoking education were in progress. Even though researches based on the knowledge about smoking and status about the teenagers were prevalent, the research based on the outcomes in long time basis were not in progress. Therefore, I tracked the people who went through 5-Day Stop-Smoking School that has taught through complexed structure of behavioral, intellectual, and psychological education. I made researches on the average of success and the hardest point during their efforts to stop just to show the necessity of going through re-education. The objectives of this study were the ones who have completed the education on the years 1990, 1991. 47 were selected from 364 people that completed the training, and who were able to be contacted on the phone line. This study was conducted from 27 Oct. to 7 Nov. 1997 through verbal interviews based on the questionnaire. The questionnaire used here was made by myself, assisted by my professor. Analysis was made through unstructured open questions. The data was analyzed using SPSS program. The major results were as follows ; 1) General characteristics of the objectives are $97.0\%$ were male, $17\%$ ages below 40s, $34\%$ in the age group of 40s, and $48.9\%$ over 50s. Religiously christian 340/0, buddhist $19.1\%$, no religion or any other reason $46.8\%$. Status married $93.6\%$, unmarried $6.4\%$. There is someone smoking in the family $36.2\%$, no one smokes $63.8\%$. Reputation salary men $55.3\%$, personal business $27.7\%$. 2) The average of success is $42.6\%(20/47)$, the failure is $57.4\%$. 3) The results from the study 'When was the hardest point in the process of stop smoking' : For the successors the first week $33.3\%$, after the first week $66.7\%$. For the failures the first week $55\%$, after first week $45\%$(Statistics not precisely done), the most effective element that helped through the hardest point was the family $40\%$, personal determination $30\%$. 4) The necessity of re-education : Successors needed $55\%$, not needed $45\%$. Failures needed $48.1\%$, not needed $51.9\%$(Statistics not precisely done). The perfect time for reeducation : Successors in 6 months $50\%$, irregular time basis $50\%$. Failures in six months $36.4\%$, after six months $27.3\%$, irregular time basis $36.4\%$(Statistics not precisely done). Synthesizing the result of the study can't generalize the long-term effect of the stop-smoking due to the number of the objectives,. but recognize the fact that 47.6 have experienced success, and also the self-determination and the support from the family are desirable. Seeing the fact that both are great motivation to stop smoking. Since the first week is necessary. The necessity of re-education is rather high, so this education should be planned to be done repeatedly in a long term along with close observation, instead of short education.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.6
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• pp.63-77
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• 2006

The research aim is to classify biotope types of rural eco-villages designed by ministry of environment and analyze landscape ecological characteristics of them. This information would provide information on eco-villages' potential and specific needs to improve landscape ecological structure of eco-villages. Two eco-villages, designated by ministry of environment, in Yoocheon-ri and Sanduk-ri were selected and the landscape ecological metrics used in this study were Area, Shannon diversity index, Shape index, Distance index. The results are as follows. 1) There were five biotope types in large-scale classification, 13 biotope types m Sanduk-ri and 9 biotope types in Yoocheon-ri in middle-scale classification, 31 biotope types in Sanduk-ri and 24 biotope types in Yoocheon-ri in small-scale classification. 2) In the case of area, artificial biotope types, such as artificial forest, agricultural irrigation canal, wet paddy, dry paddy and residential area, covered more than 80% of total area. However, natural biotope types, such as natural forest, river, reservoir, covered just more than 10% of total area. In details, an orchard (26.69%) was the dominant biotope type, followed by artificial forest (19.10%) in Sanduk-ri and the first most abundant biotope type was artificial forest (49.71%), followed by wet paddy (15.95%) in Yoocheon-ri. 3) The result of Shannon diversity index indicated that Sanduk-ri (2.158) had more heterogeneity landscape, rather than Yoocheon-ri (2.051). 4) In the case of shape index, road (13.09) had more complex and irregular shape than either agricultural irrigation canal (3.35) or artificial forest (2.46) in Sanduk-ri. Road (6.52) was also the most irregular biotope shape, followed by river (5.70) and agricultural irrigation canal (4.78) in Yoocheon-ri. 5) Mean Nearest-neighbour Distance (MND) was smallest in wet paddy and dry paddy biotope types in the two study area, suggesting that these biotope types were concentrated within these study areas. From the result, this research suggested information to protect and improve biotopes of eco-villages in the landscape ecological terms. To achieve this improvement plan, there should be strong support by ministry of environment and local governments.

• Korean Journal of Animal Reproduction
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• v.17 no.3
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• pp.221-232
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• 1993

Morphological changes in the uterine and vaginal epithelial cells of the Korean native goats were studied in fifteen primiparous goats slaughtered on the day of parturition and on days 1, 3, 10 and 21 postpartum. 15 uterus and vagina from goats were examined by scanning and transmission electron microscopy. The results obtained in this study were summarized as follows : 1. Transmission electron microscopically, long microvilli which sometimes ramified were found until 10 days postpartum, while short microvilli were found at 21 days. The high electron dense irregular-shaped mitochondria were found in the cytoplasm and the crystalline structure of the mitochondrial matrix was also found from 1 day to 10 days postpartum. Well-developed rough-endoplasmic reticulum (rER) with dilated cisternae which contained the proteins materials was observed at 21 days postpartum. These materials were fused each other and then large granules were found in the free surface of the cytoplasm. A few lipid droplets were generally appeared in the cytoplasm, while numerous droplets were found at 21 days postpartum. A moderate number of ribosomes, a few multivesicular bodies, vesicles, lysosomes and macrophages were found. The globule leucocytes were observed from 0 to 3 days postpartum by transmission electron microscopy. The short microvilli, high electron dense cytoplasm and severe indentation of the nuclear enbelope were found in the vaginal epithelium. Numerouos small vesicles and a few vacuoles were observed in the apical cytoplasmic portion of the epithelium. A few mitochondria were high electron dense and irregular in shape. A moderate amounts of microfilaments, loose intercellular space and dilated rER were also found at 21 days postpartum. 2. Scanning electron microscopically, the folds of the uterine mucosa were generally deep. The long microvilli of the epithelium were found until 3 days postpartum, while short microvili were found at 10 and 21 days postpartum. The distinct intercellular boundary was seen. The apporcine secretory profile of the epithelium observed at between 3 and 10 days postpartum and the cells were somewhat protruded into the lumen. The short microvilli were found on the surface of the protruded cells, while polygonal microridge profile of the epithelium and some dome-shaped epithelium were also observed at 21 days postpartum. The folds of the vaginal mucosa were deep and epithelium was polygonal in shape. The microvilli of the epithelium were long until 3 days postpartum, while they were short at 10 and 21 days. The polygonal epithelium was invaginated into the center of the cell surface until 10 days postpartum. The microridge and dome in shape of the epithelium were found at 10 days postpartum, while the polygonal and exfoliating epithelium were observed at 21 days.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.1
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• pp.49-64
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• 2014

Seabed beneath and near the coastal structures may undergo large excess pore water pressure composed of oscillatory and residual components in the case of long durations of high wave loading. This excess pore water pressure may reduce effective stress and, consequently, the seabed may liquefy. If the liquefaction occurs in the seabed, the structure may sink, overturn, and eventually fail. Especially, the seabed liquefaction behavior beneath a gravity-based structure under wave loading should be evaluated and considered for design purpose. In this study, to evaluate the liquefaction potential on the seabed, numerical analysis was conducted using 2-dimensional numerical wave tank. The 2-dimensional numerical wave tank was expanded to account for irregular wave fields, and to calculate the dynamic wave pressure and water particle velocity acting on the seabed and the surface boundary of the structure. The simulation results of the wave pressure and the shear stress induced by water particle velocity were used as inputs to a FLIP(Finite element analysis LIquefaction Program). Then, the FLIP evaluated the time and spatial variations in excess pore water pressure, effective stress and liquefaction potential in the seabed. Additionally, the deformation of the seabed and the displacement of the structure as a function of time were quantitatively evaluated. From the analysis, when the shear stress was considered, the liquefaction at the seabed in front of the structure was identified. Since the liquefied seabed particles have no resistance force, scour can possibly occur on the seabed. Therefore, the strength decrease of the seabed at the front of the structure due to high wave loading for the longer period of time such as a storm can increase the structural motion and consequently influence the stability of the structure.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.4
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• pp.177-186
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• 2015

Until Mandelbrot introduced the concept of fractal geometry and fractal dimension in early 1970s, it has been generally considered that the geometry of nature should be too complex and irregular to describe analytically or mathematically. Here fractal dimension indicates a non-integer number such as 0.5, 1.5, or 2.5 instead of only integers used in the traditional Euclidean geometry, i.e., 0 for point, 1 for line, 2 for area, and 3 for volume. Since his pioneering work on fractal geometry, the geometry of nature has been found fractal. Mandelbrot introduced the concept of fractal geometry. For example, fractal geometry has been found in mountains, coastlines, clouds, lightning, earthquakes, turbulence, trees and plants. Even human organs are found to be fractal. This suggests that the fractal geometry should be the law for Nature rather than the exception. Fractal geometry has a hierarchical structure consisting of the elements having the same shape, but the different sizes from the largest to the smallest. Thus, fractal geometry can be characterized by the similarity and hierarchical structure. A process requires driving energy to proceed. Otherwise, the process would stop. A hierarchical structure is considered ideal to generate such driving force. This explains why natural process or phenomena such as lightning, thunderstorm, earth quakes, and turbulence has fractal geometry. It would not be surprising to find that even the human organs such as the brain, the lung, and the circulatory system have fractal geometry. Until now, a normal frequency distribution (or Gaussian frequency distribution) has been commonly used to describe frequencies of an object. However, a log-normal frequency distribution has been most frequently found in natural phenomena and chemical processes such as corrosion and coagulation. It can be mathematically shown that if an object has a log-normal frequency distribution, it has fractal geometry. In other words, these two go hand in hand. Lastly, applying fractal principles is discussed, focusing on pulp and paper industry. The principles should be applicable to characterizing surface roughness, particle size distributions, and formation. They should be also applicable to wet-end chemistry for ideal mixing, felt and fabric design for papermaking process, dewatering, drying, creping, and post-converting such as laminating, embossing, and printing.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.1
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• pp.93-101
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• 1987

Residual stresses have remained around welding areas of a steel structure member after welding operation. The major causes to occur these residual stresses are the local heat due to a welding, the heat stresses due to a irregular and rapid cooling condition, the material and rigidity of a steel structure. Ultimatly, these residual stresses have been known to decrease a brittle fracture strength, a fatigue strength, a buckling strength, dynamic properties, and the corrosion resistance of the material. This paper deals with the residual stresses on a steel structure member through experimental studies. SWS 58 plates were welded by the method of X-groove type. These plates were layed on the heat treatment at four different temperatures; $350^{\circ}C$, $500^{\circ}C$, $650^{\circ}C$ and $800^{\circ}C$. The resulting residual Stresses were measured by hole drilling method, and the followings were obtained. The residual stresses on the vicinity of a welding point were relieved most effectively at the temperature of $650^{\circ}C$, and these stresses relieved completly when the ratio of a hole diamerter to a hole depth became unity. Hardness test shows that the higher value of hardness at the heat affected zone dropped to belower as the temperature went up from $350^{\circ}C$ to $800^{\circ}C$. The Welding input heats have not influenced the magnitude of residual stresses at the input heat range between above and below one forth than standard.

• Parasites, Hosts and Diseases
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• v.51 no.6
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• pp.633-636
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• 2013

Angiostrongylus cantonensis is a parasitic nematode that needs to develop in different hosts in different larval stages. Freshwater snails, such as Pomacea canaliculata, are the intermediate host, and rats are the definitive host. Periodic shedding of the cuticle (moulting) is an important biological process for the survival and development of the parasite in the intermediate and definitive hosts. However, there are few studies on the cuticle alterations between different stages of this parasite. In this study, we observed the ultrastructural appearance and changes of the cuticle of the 2nd/3rd stage larvae (L2/L3) and the 3rd/4th stage larvae (L3/L4) using a scanning electron microscope. We also first divided L2/L3 into late L2 and early L3. The late L2 lacked alae, but possessed a pull-chain-like fissure. Irregular alignment of spherical particles on the cuticle were noted compared to the L3. Alae appeared in the early L3. The old cuticle turned into a thin filmlike structure which adhered to the new cuticle, and spherical particles were seen regularly arranged on the surface of this structure. Regular rectangular cavities were found on the surface of L3/L4. The caudal structure of L3/L4 was much larger than that of L3, but caudal inflation, such as seen in L4, was not observed. These results are the first to reveal the ultrastructural changes of the cuticle of A. cantonensis before and after moulting of L2/L3 and L3/L4.