• Korean Journal of Agricultural Science
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• v.10 no.1
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• pp.129-134
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• 1983

Importance has been increased on farming mechanization in harvesting, handling and processing of forage in Korea. Small grasslands are most spread and popular in Korea in comparison with those of Europe and America. Therefore shearing characteristics of some major forage crops should be studied to be contributed to the basic data to develop a moderate size forage harvester being suitable to the small grassland. They were studied on six kinds of forage crops - reed canarygrass, alfalfa, red clover, orchardgrass, meadow fescue and birdsfoot trefoil-in regarding with moisture content levels and shearing angles. The results were as follows; 1. The increase rate of the linear density in relation to the diameter was greater in red clover than other kinds, and order of increase rate in greatness was reed canarygrass, alfalfa and meadow fescue. 2. The increase rates of the maximum shear forces were high in relation to their cross - sectional area in alfalfa and birdsfoot trefoil with hard stems, and the shear energy were comparatively large in orchardgrass and meadow fescue with soft stems, also reed canarygrass and red clover had high values in both the maximum shear force and the shear energy. 3. The shear energy per unit area or shear strength in relation to moisture content showed concave curves with the minimum values at about 70%w. b. which was in the beginning stage of drying in meadow fescue and orchardgrass, nevertheless reed canarygrass and red clover had convex curves with the maximum values at about 40%w.b. 4. The shear force in relation to the shear angle decreased generally with decrease of shear angle from $90^{\circ}$ to $70^{\circ}$ or $50^{\circ}$.

• Korean Journal of Agricultural Science
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• v.19 no.1
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• pp.16-27
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• 1992

To determine a potential of new sludge fertilizer for horticultural crops, comparative studies between commercial fertilizers (Jandibiryo and Wonyebokbi) and sludge fertilizer (Sludgebiryo) were made through examining the growth responses on zoysiagrass (Zoysia japponica Steud.) and several horticultural plants. 1. The pH of new sludge fertilizer remained near 6.5 regardless the particle size. The solubility of elements was highest in phosphorus, followed by nitrogen and potassium in the order. Especially, desorption of potassium was continued up to 48 hrs after solubilization. 2. There was an increase in shoot number per plant, length of stolon and rhizome, and root weight as well as clipping yield of zoysiagrass in the treatment of large size Sludgebiryo compared to small one and Jandibiryo. 3. Regardless the size of fertilizers, Sludgebiryo increased flower numbers in salvia (Salvia officinalis L. 'Hatzazz') compared to Wonyebokbi, although the difference was not great, However, leaf area and fresh weight of plant were more increased in Wonyebokbi application. 4. Flower diameter of marigold (Tagetes erecta L. 'Inca') was slightly increased in Sludgebiryo application, but the average number of lateral shoots and fresh weight per plant were significantly increased in the treatment of Wonyebokbi application. 5. Sludgebiryo effectively increased the length of both main and lateral shoots, number of flowers and weight of shoot in vinca (Vinca rosea L. 'Little Linde'), but root growth of plant was higher in Wonyebokbi application. 6, No differences between Wonyebokbi and Sludgebiryo were found in promoting the growth of leaves of perilla (Perilla frutescens Hara 'Yubsil' ), but chlorophyll content and seed weight were slightly higher in the application of Wonyebokbi compared to Sludgebiryo. In conclusion, the effectiveness of Sludgebiryo for horticultural plants was almost equal to commercial fertilizers such as Jandibiryo or Wonyebokbi. Expecially, Sludgebiryo appeared to effective on the growth of zoysiagrass, and the increase of flower size and numbers in flower crops. Results indicate that new-made Sludgebiryo can be recommended for turfgrass culture, and the flower crops in which quality depends on flower number and flower size.

• Korean Journal of Agricultural Science
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• v.19 no.2
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• pp.129-135
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• 1992

Characteristics of ten glutinous maize hybrids developed at the Genetics and Breeding Lab. of Department of Agronomy, College of Agriculture, Chungnam National University were compared. Inbred lines used in the development of the ten hybrids were all originated from the Korean local maize lines which were collected in 1980s and they were developed by ear-to-row method. All the inbreds used had very unique plant characteristics such as plant height, ear height, ear length, ear diameter, 100 kernel weight and kernel color. The highest inbred in plant height was Jewon and the Jewon was also highest in ear height. While the ear of Jewon inbred was slender and slimmy, the ear of Dangjin inbred was rather short and promp. 100 kernel weight of the Bosung inbred was highest and the kernel weight of Chilbo was lightest. Kernel color of Jewon, Bosung and Danyang was white and the kernel color of Yunghee and Chilbo was purple. Dangjin had yellow kernel color. A total of 11 hybrids including one check hybrid developed by the Crop Experiment Station, ADR were included in performance trial. The hybrids which showed high grain yield were Dangjin/Bosung, Sosung/Dangjin and Dangjin/Chilbo. These hybrids were about 10% higher than the check in yield capacity. Each hybrid had also unique characteristics such as plant height, ear height and flowering date.

• Korean Journal of Crystallography
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• v.6 no.1
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• pp.1-13
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• 1995

Cr:A12O3 and Ti:A12O3 single crystals were grown by Czochralski method, and the effects of crystal growth parameters such as pulling rate, rotation rate, dopant and growth atmosphere on crystal quality were investigated. And spectroscopic properties including lasing efficiency were also measured. Single crystals, sized of 20mm in diameter and 100-135mm in length, were successfully grown from the seed of <001> direction. With the doping level of 0.5w/o Cr2O3, pulling rate 2.0mm/hr, rotation rate of 30rpm and inert atmosphere by nitrogen gas, high quality crystals of Cr:A12O3 were grown. While in case of Ti:A12O3 crystals, high quality crystals were grown under the conditions of the doping level of 0.25w/o TiO2, pulling rate of 1.5mm/hr, rotation rate of 30rpm and reducing atmosphere by hydrogen - nitrogen mixed gas. It was confirmed that Cr3+ ion which maintains its ionoc valence during growth easily de-bubbled than Ti4+ ion which changes its valence, Fe3+ ion also has do-bubbling effect to Ti:A12O3 crystal and the reducing atmosphere by 90% N2 - 10% H2 mixed gas gave effective result on the changing of Ti4+ to Ti3+ and de-bubbling. As a result of spectroscopic measurements of Cr:A12O3 crystal, 4A2 →4F2 and 4F1 absorption transitions and E →4A2(R1) and 2A →4A2(R2) fluorenscence transitions were confirmed. And it was measured that wavelengths of laser R1 and R2 transitions were 696±5nm and 692±5nm respectively, line width of these transitions were 12A, and life-time of fluorenscence was 152μsec. In case of Ti:A12O3 crystals, it was confirmed that absortion transition of 4T2→4E and fluorescence transition of 4E→4T2 with wide range of 650-1050nm was occured. And 147μsec of life-time of fluorescence, 125.4 of figure of merit and 9% of laser efficience were also measured.

• Tuberculosis and Respiratory Diseases
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• v.40 no.2
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• pp.158-164
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• 1993

Background: Recently, lung abscess tends to be increased in patients with underlying disease, most of whom are unsuitable for surgery when medical treatment fails. The patients with giant lung abscesses do not frequently respond to antibiotics and often have life-threatening complications. Therefore, more intensive cares are required in these patients. We studied the results and effects of percutaneous catheter drainage in these patients. Method: We performed fluoroscopy-guided percutaneous pigtail catheter (8.3 F) drainage by Seldinger technique in 9 cases of lung abscess (in 7 cases, intractable to medical treatment for an average of 8.4 days and in 2 cases, catheter drainage immediately performed due to a large cavity that was initially 10 cm in diameter). We compared 10 cases of lung abscess as control group which had receieved conventional medical treatment alone. Results: Seven of the 9 patients in study group of percutaneous drainage and 7 of the 10 patients in control group of medical treatment alone clinically improved in the average of 1.8 and 8.7 days, respectively. The mean duration of drainage was 13.2 days. There were 3 cases of death from massive hemoptysis, asphyxia of pus, and sepsis in control group, as compared with 2 cases of death from hepatic encephalopathy and sepsis in study group. The malfunctions of catheter occurred in these 2 cases, obstruction and dislodgement. But there were no significant pleuropulmonary complications of percutaneous drainage. Conclusion: Percutaneous drainage is effective and relatively safe in the management of lung abscesses refractory to medical therapy or giant lung abscesses.

• Tuberculosis and Respiratory Diseases
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• v.60 no.6
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• pp.663-672
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• 2006

Background: $PM_{10}$(Particulate matter with a diameter ($<10{\mu}m$), which is characterized by different environmental conditions, is a complex mixture of organic and inorganic compounds. The Asian dust event caused by meteorological phenomena can also produce unique particulate matter in affected areas. This study investigated the cytokine produced by A549 epithelial cells exposed to particles collected during both the Asian dust pfenomenon and ambient air particles in a non-dusty period. Method: Air samples were collected using a high volume air sampler(Sibata Model HV500F) with an air flow at $500{\ell}/min$ for at least 6 hours. The cytokine messenger RNA(mRNA) was measured using a reverse transcriptase polymerase chain reaction(RT-PCR). The A549 cells were exposed to 10 to $500{\mu}g/m{\ell}$ of a suspension containing $PM_{10}$ for 24 hours. Each was compared with those in the non-exposed control cells. Result: The mRNA levels of interleukin(IL)-$1{\alpha}$, $IL-I{\beta}$, IL-8, and the granulocyte macrophage colony stimulating factor(GM-CSF) increased after veing exposed to $PM_{10}$ in the ambient air particles, compared with those in the non-exposed control cells. The increase in $IL-1{\alpha}$ and IL-8 were dose dependent at a $PM_{10}$ concentration between $100{\mu}g/m{\ell}$ and $500{\mu}g/m{\ell}$. The mRNA level of IL-8 in the A549 epithelial cells was higher during the in the Asian dust period($500{\mu}g/m{\ell}$) than during the non dust period. Conclusion: A549 cells exposed to the $PM_{10}$ collected during the Asian dust period produce more proinflammatory cytokine than during non-dusty period. This cytokine enhances the local inflammatory response in the airways and can also contribute to the systemic component of this inflammatory process.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.1
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• pp.16-27
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• 2010

Purpose: The aim of this experimental study is to observe the effect of platelet-rich plasma (PRP) on early bone regeneration of rats both in normal condition and in osteoporosis induced by ovariectomy. Material and methods: Total 40 Sprague-Dawley female rats were divided into 4 groups. A 8-mm-diameter calvarial critical-sized defect (CSD) was made by drilling with trephine at the center of calvaria in cranium of every rat. Every CSD was augmented with an osteoconductive synthetic alloplastic substitute ($MBCP^{TM}$) and PRP as follows. Group A; 10 non-ovariectomized rats grafted with only $MBCP^{TM}$. Group B; 10 non-ovariectomized rats grafted with $MBCP^{TM}$ and PRP. Group C; 10 ovariectomized rats grafted with only $MBCP^{TM}$. Group D; 10 ovariectomized rats grafted with $MBCP^{TM}$ and PRP. At 4 weeks after graft, every rat was sacrificed. And histomorphometric analysis was performed by measuring calcified area of new bone formation within the CSD. Results: Comparing four groups, results were obtained as follows. 1. In non-ovariectomized groups, PRP showed a positive effect somewhat but not significant (P > .05). 2. In ovariectomized groups, PRP showed a positive effect significantly (P < .05). 3. In PRP untreated groups, ovariectomy diminished bone regeneration significantly (P < .05). 4. In PRP treated groups, ovariectomy diminished bone regeneration somewhat but not significant (P > .05). Conclusion: Within the limitation of this study, it can be concluded that PRP in combination with an osteoconductive synthetic alloplastic substitute has an effect on bone regeneration more significantly in ovariectomized osteoporotic rats than in normal rats.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.191-198
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• 2009

Statement of problem: Ceramics have been important materials for the restoration of teeth. The demands of patients for tooth-colored restorations and the availability of various dental ceramics has driven the increased use of new types of dental ceramic materials. Improved physical properties of theses materials have expanded its use even in posterior crowns and fixed partial dentures. However, ceramic still has limitation such as low loading capability. This is critical for long-span bridge, because bridge is more subject to tensile force. Purpose: The wire reinforced ceramic was designed to increase the fracture resistance of ceramic restoration. The purpose of this study was to evaluate the fracture resistance of wire reinforced ceramic. Material and methods: Heat pressed ceramic(ingot No.200 : IPS Empress 2, Ivoclar Vivadent, Liechtenstein) and Ni-Cr wire(Alfa Aesar, Johnson Matthey Company, USA) of 0.41 mm diameter were used in this study. Five groups of twelve uniform sized ceramic specimens(width 4 mm, thickness 2 mm, length 15 mm) were fabricated. Each group had different wire arrangement. Wireless ceramic was used as control group. The experimental groups were divided according to wire number and position. One, two and three strands of wires were positioned on the longitudinal axis of specimen. In another experimental group, three strands of wires positioned on the longitudinal axis and five strands of wires positioned on the transverse axis. Three-point bending test was done with universal testing machine(Z020, Zwick, Germany) to compare the flexural modulus, flexural strength, strain at fracture and fracture toughness of each group. Fractured ceramic specimens were cross-sectioned with caborundum disc and grinded with sandpaper to observe interface between ceramic and Ni-Cr wire. The interface between ceramic and Ni-Cr wire was analyzed with scanning electron microscope(JSM-6360, JEOL, Japan) under platinum coating. Results: The results obtained were as follows: 1. The average and standard deviation in flexural modulus, flexural strength and fracture toughness showed no statistical differences between control and experimental groups. However, strain was significantly increased in wire inserted ceramics(P<.001). 2. Control group showed wedge fracture aspects across specimen, while experimental groups showed cracks across specimen. 3. Scanning electron microscopic image of cross-sectioned and longitudinally-sectioned specimens showed no gap at the interface between ceramic and Ni-Cr wire. Conclusion: The results of this study showed that wire inserted ceramics have a high strain characteristic. However, wire inserted ceramics was not enough to use at posterior area of mouth in relation to flexural modulus and flexural strength. Therefore, we need further studies.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.4
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• pp.308-315
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• 2011

Purpose: The purpose of this study was to colorimetrically evaluate the masking effect of different opacity of ingots on the final shade of IPS Empress Esthetic$^{(R)}$ laminate veneer restorations using the CIE $L^*a^*b^*$ system. Materials and methods: Six porcelain disks of IPS Empress Esthetic$^{(R)}$ system (translucency: E 01, E 03, E 0C-1, E TC-1, E TC-2, E TC-3) were fabricated with 7 mm in diameter and 0.6 mm in thickness. Six extracted human incisors (shade: A1, A3, A4, B2, B3, C3) were used as the abutment specimens. The incisors were prepared using a diamond wheel and made with a flat labial surface on the middle 1/3. For each combination of different shades of abutments and copings, the change in color was measured with a colorimeter. CIE $L^*a^*b^*$ coordinates were recorded for each specimen. Color differences (${\Delta}E$) were calculated. Descriptive statistical analysis was done. Results: ${\Delta}E$ values were significantly affected by coping translucency and abutment shade (P<.05). The color differences (${\Delta}E$) of laminate veneers among abutments with A3, B3, C3, and A4 shade were mostly below 2.7 which was within the clinically acceptable range, while color differences between A4 and B2, A3 and B2, and A1 and A4 showed more than 2.7. Conclusion: The final color of IPS Empress Esthetic$^{(R)}$ laminate veneers were significantly influenced by translucency of the coping and shade of abutment teeth. The large value difference of abutment teeth limited the masking ability by laminate veneers.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.4
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• pp.316-323
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• 2011

Purpose: The purpose of this study was to investigate the effect of different thread designs on the marginal bone stresses around dental implant. Materials and methods: Standard ITI implant(ITI Dental Implant System; Straumann AG, Waldenburg, Switzerland), 4.1 mm in diameter and 10 mm in length, was selected as control. Test implants of four different thread patterns were created based on control implant, i.e. maintaining all geometrical design of control implant except thread pattern. Four thread designs used in test implants include (1) small V-shape screw (model A), (2) large V-shape screw (model B), (3) buttress screw (model C), and (4) trapezoid screw (model D). Surface area for unit length of implant was 14.4 $mm^2$ (control), 21.7 (small V-shape screw), 20.6 (large V-shape screw), 17.0 (buttress screw) and 28.7 $mm^2$ (trapezoid screw). Finite element models of implant/bone complex were created using an axisymmetric scheme with the use of NISA II/DISPLAY III (Engineering Mechanics Research Corporation, Troy, MI, USA). A load of 100 N applied to the central node on the crown top either in parallel direction or at 30 degree to the implant axis (in order to apply non-axial load to the implant NKTP type 34 element was employed). Quantification and comparison of the peak stress in the marginal bone of each implant model was made using a series of regression analyses based on the stress data calculated at the 5 reference points which were set at 0.2, 0.4, 0.6, 0.8 and 1.0 mm from implant wall on the marginal bone surface. Results: Results showed that although severe stress concentration on the marginal bone cannot be avoided a substantial reduction in the peak stress is achievable using different thread design. The peak marginal bone stresses under vertical loading condition were 7.84, 6.45, 5.96, 6.85, 5.39 MPa for control and model A, B, C and D, respectively. And 29.18, 26.45, 25.12, 27.37, 23.58 MPa when subject to inclined loading. Conclusion: It was concluded that the thread design is an important influential factor to the marginal bone stresses.