• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.2
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• pp.170-178
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• 2015

In this study, it was developed eco-friendly alkali-activated slag fiber reinforced concrete using ground granulated blast furnace slag, alkali activator (water glass, sodium hydroxides), and steel fiber. Eight reinforced concrete beam using alkali-activated slag concrete were constructed and tested under monotonic loading. The major variables were mixture ratio of alkali activator, mixed/without of steel fiber. Experimental programs were carried out to improve and evaluate the flexural performance of such test specimens, such as the load-displacement, the failure mode, the maximum load carrying capacity, and ductility capacity. All the specimens were modeled in scale-down size. The reinforced concrete beams using the eco-friendly alkali-activated slag fiber reinforced concrete was failed by the flexure or flexure-shear in general. In addition, the maximum strength increased with the adding the mol of sodium hydroxide, and the specimen reinforced the steel fiber showed the value of maximum strength which is increased by 15.8% through 25.9%. It is thought that eco-friendly alkali-activated slag fiber reinforced concrete can be used with construction material and product to replace normal concrete. If there is applied to structures such as precast concrete member and production of 2nd concrete product, it could be improved the productivity and reduction of construction duration etc.

• Journal of Chest Surgery
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• v.17 no.1
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• pp.118-124
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• 1984

Congenital Cystic Adenomatiod Malformation (C.C.A.M.) is rare, but one of the most common congenital pulmonary anomalies that cause acute respiratory distress in the newborn infants. It is characterized and differentiated from the diffuse pulmonary cystic disease pathologically, i.e. adenomatoid appearance due to marked proliferation of the terminal respiratory components. An 2/12 year old male patient was suffered from respiratory distress and cyanosis on crying since birth, but no specific therapy was given. With progression of symptoms, he came to Korea University Hospital for further evaluation and then transfered to Dept. of Chest Surgery for operative correction under the impression of Congenital Obstructive Emphysema suggested by a pediatrician. On gestational and family history, there was nothing to be concerned such as congenital anomaly. Physical examinations showed; moderate nourishment and development (Wt. 5.5kg), cyanosis on crying, both intercostal and lower sternal retraction on inspiration, Lt. chest building with tympany, Rt. shifting of cardiac dullness, decreased breathing sound with expiratory wheezing on entire Lt. lung field, decreased breathing sound on Rt. upper lung filed, and tachycardia. The remainders were nonspecific. Laboratory findings were normal except WBC $14000/mm^3$ (lymphocyte 70%), Hgb 9.8m%, Hct 28%, negative Mantaux test, and sinus tachycardia and counter-clockwise rotation on EKG. Preoperative simple Chest PA revealed marked hyperlucent entire Lt. lung, herniation of Lt. upper lobe to Rt., collapsed Rt. upper lobe, tracheal deviation and mediastinal shifting to Rt., and no pleural reaction. At operation, after Lt. posterolateral thoracotomy, 4th rib was resected. Operative findings were severe emphysematous changes limited to both lingular segmentectomy was done. The resected specimen showed slight solidity, measuring $8{\times}4.5{\times}2cm$ in size, and small multiple cystic spaces filled with air. Microscopically, entire tissue structures were glandular in appearance, cyst were lined by ciliated columnar epithelium, and occasional cartilages were noted around the cystic spaces. Bronchial elements were dilated but normal pattern on histologically. The patient had a good postoperative courses clinically and radiologically, and discharged on POD 10th without event. The authors report a case of Cogenital Cystic Adenomatoid Malformation (C.C.A.M.)

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.156-165
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• 1999

The purpose of this study was to evaluate the effect of surface treatments on the shear bond strength between new and old composites. Circular cavities prepared on the center of acrylic resin mold and the prepared cavities were filled with composite resin. They randomly assigned into control group and 8 groups according to the difference in surface treatments of old composites; Control group: no surface treatment, Group 1: surface treated with #120 SiC paper & bonding agent, Group 2: surface treated with #400 SiC paper & bonding agent, Group 3: surface treated with #120 SiC paper, 32% $H_3PO_4$ & bonding agent, Group 4: surface treated with #400 SiC paper, 32% $H_3PO_4$ & bonding agent, Group 5: surface treated with #120 SiC paper, primer & bonding agent, Group 6: surface treated with #400 SiC paper, primer & bonding agent, Group 7: surface treated with #120 SiC paper, 32% $H_3PO_4$, primer & bonding agent, Group 8: surface treated with #400 SiC paper, 32% $H_3PO_4$, primer & bonding agent. New composites were applicated on the old composites of experimental groups. The shear bond strengths for the experimental specimen were measured and the results were analyzed by using one way ANOVA. The observations of surface morphology after SiC paper roughening and debonded surface morphology after shear bond strength test were done by SEM. The results were as follows; 1. Shear bond strengths for specimens roughened with #120 SiC paper matching with the particle size of coarse diamond bur were significantly higher than those for the specimens with #400 SiC paper(P<0.05). By SEM, the surface of the specimens roughened with #120 SiC paper was more irregular than the specimens with #400 SiC paper. 2. Shear bond strengths for specimens treated with 32% $H_3PO_4$ etchant, primer, bonding resin were significantly higher than those for specimens treated with 32% $H_3PO_4$ and bonding resin(P<0.05). 3. Shear bond strengths for the specimens treated with 32% $H_3PO_4$ etchant and bonding resin were significantly higher than those for specimens treated with only bonding resin(P<0.05). There was no remarkable change of surface morphology after 32% $H_3PO_4$ etching. 4. It was possible to observe mixed fracture patterns (the cohesive fracture of old composite and the adhesive fracture between old and new composite) in the specimens roughened with #120 SiC paper, but almost adhesive fracture in the specimens roughened with #400 SiC paper.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.12
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• pp.7657-7661
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• 2013

Background: This study concerns uptake and results of colorectal cancer (CRC) screening of government servant as part of the Health Screening Program that was conducted in Brunei Darussalam in 2009. Materials and Methods: Government servants above the age of 40 or with family history of CRC were screened with a single fecal occult blood test (FIT, immunohistochemistry). Among 11,576 eligible subjects, 7,360 (66.9%) returned their specimen. Subjects with positive family history of CRC (n=329) or polyps (n=135) were advised to attend clinics to arrange screening. All the subjects with positive FIT (n=142, 1.9%) were referred to the endoscopy unit for counselling for screening colonoscopy. Results: Overall only 17.7% of eligible subjects attended for screening; 54.9% (n=79/142) of positive FIT, 8.8% (n=29/329) of positive family history of CRC and none with history of polyps (n=0/135). Of these, only 54 patients (50.5%) agreed for colonoscopy, 52 (48.6%) declined as they were asymptomatic, and one was not offered (0.9%) due to his very young age. On screening colonoscopy, 12.9% (n=7) had advanced lesions including a sigmoid carcinoma in situ and six advanced polyps. The other findings included non advanced polyps (n=21), diverticular (n=11) and hemorrhoids (n=26). One patient who missed his screening colonoscopy appointment re-presented two years later and was diagnosed with advanced right sided CRC. All the advanced lesions were detected in patients with positive FIT, giving a yield of 20.5% for advanced lesions including cancers in the 5.1% FIT positive subjects. Conclusions: Our study showed screening for CRC even with a single FIT was effective. However, the uptake rate was poor with just over half of the patients agreeing to screening colonoscopy. Measures to increase public awareness are important. Since one limitation of our study was the relatively small sample size, larger studies should be conduced in future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.278-284
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• 2017

In this study, the heat input conditions suitable for the AZ61 magnesium alloy were derived by controlling the welding speed at a constant rotational speed. In addition, from an economic point of view, industry demands higher welding speeds. Therefore,the effects of the welding speed were studied. The rotational speed applied was 800rpm, and the welding speed was varied from 100 to 500mm/min to evaluate the behavior of the welded regions. Tensile and hardness tests were conducted to examine the mechanical properties. Optical microscopy was used to observe the microstructure and soundness of the welded regions. Defects were observed at the welded region when the welding speed was more than400mm/min. As the welding speed increased, the grain size of the stir zone decreased and the hardness tended to increase proportionally. When the rotational speed was 800 rpm and the welding speed was 200mm/min and 300mm/min, there wereno defects in the welded region and excellent mechanical properties were recorded. In addition, the joint efficiencies were 100.5% and 101.2%, respectively, and the ultimate tensile strength was similar to that of the base metal. Fracture of the tensile specimen occurred between the advancing side and stir zone, and the fracture location coincided with the region where the hardness decreased temporarily.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.6
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• pp.268-273
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• 2014

$Y_2O_3$ ceramic specimens were fabricated from the granular powder, obtained by spray drying process from the slurry. The slurry was prepared by mixing PVA binder, NaOH for Ph control, PEG and $Y_2O_3$ powder. The $Y_2O_3$ specimen was shaped in size of ${\phi}14mm$ and then sintered at $1650^{\circ}C$. The characteristics, microstructure, densities and plasma resistance of the $Y_2O_3$ specimens were investigated with the function of forming pressure and sintering time. $Y_2O_3$ specimens were exposed under the $CHF_3/O_2/Ar$ plasma, the dry etching treatment of specimens was carried out by the physical reaction etching of $Ar^+$ ion beam and the chemical reaction etching of $F^-$ ion decomposed from $CHF_3$. With increasing sintering time, $Y_2O_3$ specimens showed relatively high density and strong resistance in plasma etching test.

• Journal of the Korea Concrete Institute
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• v.14 no.6
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• pp.805-812
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• 2002

The number of old concrete structure which needs to be strengthened has been increased. The repair and strengthening methods have to be determined based on the current status of the structure. Consequently the estimation method for the damage status of the structure has been desperately needed, but no studies have been tried to use the crack and deflection characteristics to estimate the damage status. In this study, the crack characteristics depending on load level were measured and analysed. The crack characteristics observed from 11 samples were compared with damage status, and load level, The crack characteristics examined in this study include crack number, crack length, crack range, crack interval, maximum crack length, crack area, and average crack length. The deflections were normalized based on yield deflection, and the relationship between the relative deflection and the standardized crack characteristics were compared. Among the crack characteristics, crack interval, crack area, crack range, and maximum crack length, have been showed a close relationship to the relative deflection. Therefore, if such crack characteristics are evaluated, the maximum load applied to the structure is believed to be estimated. if additional parameters such as size of specimen, strength of concrete and steel, and steel ratio are studied, the damage status of structure can be estimated more accurately.

• Journal of the Korea Concrete Institute
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• v.21 no.4
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• pp.457-464
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• 2009

Fiber is an important ingredient in fiber-reinforced cement composite (FRCC) which can control fracture of cement composite by bridging action. In compliance with the action of the fiber and the aggregate size, it also showed a different failure mechanism. For practical application, it is needed to investigate the fracture behavior of the FRCC and to understand the micro-mechanism of cement matrix with reinforcing fiber. In order to evaluate a characteristics of fracture process in the FRCC, acoustic emission (AE) technique was used for the analysis and evaluation of FRCC damage by acoustic emission under flexural and cyclic compressive loadings. The AE signals were monitored by AMSY4 AE instrument during the entire loading period. The specimens are reinforced with 0, 1.0, 1.5 and 2.0% (by volume) Polyvinyl alcohol (PVA) fiber. The test results showed that the damage progress of the FRCC was characteristic for the fiber replacement ratio. As a result of analyzing the felicity ratio (FR) values, it is shown that this values can be used for evaluating the degree of FRCC damage. On the whole the felicity ratio values of FRCC are shown between 0.4 and 1.1. And, the AE kaiser effect was shown in the all FRCC specimen. In addition, the damage behavior and the microscopic fracture process of the FRCC are evaluated using the AE parameters, such as calm ratio, b-value and felicity ratio. The purpose of this reserch was to advance the state of knowledge regarding the applicability of acoustic emission as an evaluation method for FRCC.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.2
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• pp.173-180
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• 2013

Compacted graphite iron(CGI), also known as vermicular graphite iron, is a metal which is gaining popularity in applications that require either greater strength, or lower weight than cast iron. Recently compacted graphite iron has been used for diesel engine blocks. Considering that using in exhaust manifold of the diesel engine, CGI340 was conducted the heat treatment during 1 hour to 96 hours from 873 to 1273 K. Mechanical characteristics were evaluated. The obtained results are as follows; The tensile strength of the heat treated specimens showed overall lower tensile strength than that of the base metal. Tensile strength decreases with increasing of heat treatment time, and the higher heat treatment temperature and the longer time, were more reduced. The fatigue limit by the ultrasonic fatigue test was approximately 130 MPa of base metal, 100 MPa of 1173 K (96 hrs) specimen, respectively. The hardness decreases with increasing heat treatment time, and the higher the heat treatment temperature was lowered hardness distribution. In CGI340, average hardness of nodular graphite was 120 Hv, average hardness of vermicular graphite was 114 Hv. This showed lower hardness than the base structure ferrite. The nodular graphite and vermicular graphite according to the heat treatment temperature and time didn't have a consistent change. However, the grain size of base structure grew with increasing of heat treatment time.

• Korean Journal of Veterinary Service
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• v.18 no.2
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• pp.133-151
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• 1995

During 2 years from Octorber 1992 to April 1994, prevalence of general respiratory diseases and atrophic rhinitis in the pig herds located in the Western Chungnam was investigated, and isolation of B. bronchiseptica was attempted for the pigs manifested with the clinical signs of atrophic rhinitis(AR). The isolates were characterized and identified in aspects of biochemical properties, antigenicity, drug sensitivity and pathogenicity. The results obtained through the experiments are summarized as follows; 1. During 2 years of investigation, the overall prevalence of the general respiratory diseases in the pi8 herds in Western Chungnam was 35.3%, consisting of 35.1% in the pig farms and 38.8% in a slaughter house. The prevalence by age groups accounts for 9.2% in adults, 44.7% in rearings and 25.3% in sucklings. By farm size, The highest prevalence of 56.5% was observed in the smallest farm with 1 to 200 heads. 2. The prevalence of clinical cases of artrophic rhinitis was recorded by 12.7% in the group that is the sows and piglets vaccinated, 28.9% in the group that is the sows only vaccinated and 39.8% in the group of the non-vaccinated groups. In the slaughter house, 53(24.8%) of 214 pigs examined exhibit the AR lesions. 3. A total of 189 strains of B. bronchiseptica were isolated from the pig herds. Isolation rates were 12.6% in the group that is the sows and piglets vaccinated, 34.1% in the group that is the sows only vaccinated and 45.7% in the group of the non-vaccinated groups. Isolation rate in the specimen from the slaughter house was 93( 43.5% ) of 214 pigs examined. Of the AR-non-vaccinated group, the piglets aged bet- ween 61 to 90 days revealed the highest isolation rate of 58.5%. 4. The titers of antibody against B. bronchiseptica were measured by tube agglutination test. The group that is the sow and piglet-vaccinated showed the highest titer of 640-2, 560 in sow and 640longrightarrow5, 120 in piglet. The group that is the sows only-vaccinated revealed 640-2, 560 in sows and 640-1, 280 in piglets. Both of the vaccinated groups showed 100% positive reaction. The group of the non-vaccinated sho-wed relatively lower titer of 0-1, 280 in both of sows and piglets. The positive rate of the sera obtained from the slaughter house was 53.3% with the antibody titer of 0-1, 280. 5. Biochemical and serological properities of 189 isolates were very similar to those of the reference B. bronchiseptical phase I type, indicating that most of isolates are B. bronchiseptica phase I type. 6. In antimicrobial drug susceptibility, 87.3% of 189 isolates was susceptible to chloramphenicol, 79.9%, to amikacin, 64.6%, to cephalothin and less than 35.4% to others. 7. In agar-gel immunodiffusion and SDS-PAGE analysis, the isolates presented the identical antigenicity and protein profiles to the reference standard strains. 8. The whole cells and bacterial filtrates of the isolates were inoculated to guinea pigs and mice. The isolates showed the hish pathogenicity and dermonecrotoxiciy.