• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.65 no.4
• /
• pp.468-476
• /
• 2020

This study was performed to establish light intensity conditions for producing stem cuttings for aeroponic systems suitable for seed potato production using a closed-type plant production system. Shoot tip cultured plantlets of 'Sumi' and 'Chubaek' potato (Solanum tuberosum L.) were acclimatized, cuttings were collected, and stem cuttings were planted. The seedlings were raised for 40 days at different LED light intensities (60, 120, 180, and 240 μmol·m^-2·s^-1), and were cultivated in an aeroponic system for 80 days. When stem cuttings were raised at 60 μmol·m^-2·s^-1 LED light intensity, the plant height was the longest, at 17.3 cm for 'Sumi' and 16.1 cm for 'Chubaek', and the number of nodes was the highest in both cultivars. The higher light intensities, produced smaller plants with fewer nodes. The leaf areas, SPAD values, and Fv/Fm values differed slightly between cultivars. The fresh weight of stem cuttings, and the production rate of healthy stem cuttings were the highest at 60 μmol·m^-2·s^-1. In the aeroponic system, seedlings raised at 60 μmol·m^-2·s^-1 with LED light intensity showed a difference between the cultivars, but the fresh weight of stems and leaves above the planting plate was the heaviest. In addition, below the planting plate the stem cuttings were longest and the root weight was heaviest at 60 μmol·m^-2·s^-1 LED light intensity. The number of stolons also differed between cultivars, but was greatest for seedlings raised at 60 μmol·m^-2·s^-1 LED light intensity, at 4.2/plant for 'Sumi' and 7.7/plant for 'Chubaek'. At 60 μmol·m^-2·s^-1 LED light intensity, the tuber number and total tuber weight were the best, but the higher the light intensity, the smaller the total tuber number and total tuber weight for both cultivars. In conclusion, when producing potato stem cuttings for aeroponic systems using a closed-type plant production system, the most suitable LED light intensity for raising seedlings was found to be 60 μmol·m^-2·s^-1.

• The korean journal of orthodontics
• /
• v.34 no.6 s.107
• /
• pp.526-536
• /
• 2004

This study was undertaken to determine the effect of a 2.2mg/Kg/day intraoral administration of NaF on the amount of root resorption and osteoclastic activity during or after a rapid maxillary expansion procedure. Ten puerile female dogs were divided into two groups: a control group and a NaF-treated group. A fixed type maxillary expansion device was delivered to all dogs. The appliance was activated twice daily throughout a 20-day period, causing a 5-mm expansion of maxillary bone. After the expansion procedure, the animals were sacrificed at days 0, 15, 30, 45, and 60 of the retention period. The buccal surface of the root of each maxillary canine was examined by means of a surface electron microscope (SEM). Using SEM, web-like resorption lacunae were observed on the bone or the tooth surface at the site of osteoclastic activity; these observations were verified by histological methods. No peculiar resorption lacunae were found in the apical tip of the roots of either the control group or the NaF-treated group animals. The NaF-treated retention group was found to have less resorption lacunae formation on day 45 and day 60. The preventative effect of NaF on resorption lacunae formation on the surface of the bone covering the anchor tooth was confirmed. Larger areas of resorption lacunae were found on the surface of the bone covering the canines in the control group animals, as compared to those of the NaF-treated group, especially on day 30 and day 60. Using SEM, the present study revealed a difference between the control group and the NaF-treated group in the prevalence and the size of the resorption lacunae formation on the cemental root surface. The preventative effect of NaF on bone resorption was confirmed. Further studies concerned with the optimum concentration of NaF that has an effect in vivo are necessary.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.21 no.2
• /
• pp.165-179
• /
• 1991

This study was performed to understand the irradiation effects on the mandibular condyle and mandibular growth in developing white rats. Forty eight white male rats of the Sprague-Dawley strain aged 4 weeks, were devided into two groups; control group and experimental group. A single target dose of l0Gy of radiation was given to the mandibular condylar area and the observations of the photo analysis, radiologic, histopathologic and immunohistochemical study revealed as follows; 1. Animals killed one week after irradiation showed lesser increase in body weights, no difference in photo analysis and decreased thickness of cartilagenous layers of the condyle than the control group. 2. Two weeks after irradiation the weight increases were almost same in both irradiated and control groups and in photo analysis, the distance from Mental Foramen to Incisal tip (Mf-It) was longer than the controls. Repair processes were taken place in irradiated group, but the cartilagenous layers were thinner than the controls. 3. By the third week after exposure further repair was seen in the trabeculae and the distance from Condylion to Mandibular plane (Cd-Cd') was longer than the controls and the weight increases were almost same as the controls. 4. At 4 weeks after irradiation the cells of proliferating zone repaired to almost normal findings, but the cartilagenous cell layers were still thinner than the control animals. In photo analysis, the distances from Menton to Anterior Notch (Me-An), from First Molar to Mandibular plane (Fm-Fm') were shorter and the weight increases were lesser than the controls. 5. In the S-100 antibody, the positive cells were increased in number, but decreased reactivities were seen at the proliferating zone of the irradiated groups. In the Monoclonal Anti-Proteoglycan antibody and Type Ⅰ collagen antibody, the irradiated groups showed little decreased number of positive cells and in the Type Ⅱ collagen antibody, the differences between irradiated and control groups were undetectable in immunohistochemical study.

• Journal of Periodontal and Implant Science
• /
• v.32 no.2
• /
• pp.315-324
• /
• 2002

The purpose of this in vitro study was to evaluate the efficiency of Er:YAG laser on calculus removal and the morphologic changes and hardness of the irradiated surface at different power settings. This experiment used human teeth which were extracted due to periodontal disease and had a band of calculus. Forty root slabs ($5{\times}5mm$) were made and divided into control group and irradiated groups. Experimental groups were as follows; Control group (root planing), Group1 (irradiated with laser at 30mJ), Group2 (irradiated with laser at 60mJ), Group3 (irradiated with laser at 100mJ). Twelve root slab embedded in resin block were used in each group. Er:YAG laser was applied under water irrigation with the tip held perpendicular to the root surface in contact mode. The treatment time was measured until the calculus was removed completely under naked eyes. The efficiency of calculus removal was evaluated by the time for removal. Morphological changes of laser irradiated site were observed under SEM and the surface hardness was measured using a VH tester. The results were as follows; 1. The efficiency of laser scaling was increased with increasing the energy level of irradiation(p<0.05). 2. The morphological changes such as carbonization, crater and scale-like defects in the irradiated root surface were frequently observed with increasing the energy level. 3. The surface hardness tended to increase at 60mJ and 100mJ irradiated groups than that of control group. From the results evaluting on the efficiency, morphological change and surface hardness, lower energy level was suggested for the clinical application of the Er:YAG laser in scaling.

• Journal of Periodontal and Implant Science
• /
• v.32 no.2
• /
• pp.303-314
• /
• 2002

This study was performed to evaluate the usability of Er:YAG laser for periodontal therapy. Forty dental root slabs ($5{\times}5{\times}2mm^3$) were prepared from human periodontally diseased extracted teeth and grouped into 4 groups: 1) control (root planing only), 2) root planing and irradiated with laser at 30mJ, 3) root planing and irradiated with laser at 60mJ, and 4) root planing and irradiated with laser at 100mJ. The root slabs were embedded in resin block before laser treatment. Er:YAG laser was irradiated under water irrigation with the tip held perpendicular to the root surface in contact mode. After Er:YAG laser irradiation or planing on the root surface, morphological changes have been observed under SEM, and the micro-hardness and Ca/P ratio were compared. 1. In the Control group, the root surface showed the directional change caused by root planing instrumentation, and the presence of smear layer, and no exposure of dentinal tubule was observed. Laser irradiated group showed surface changes with rough dentin surface of niche and depression and dentinal tubule exposure by the elimination of smear layer. 2. The micro-hardness of root surface in the laser irradiated group was higher than the control group. The higher energy output was applied, the higher micro-hardness on root surface was resulted. 3. The higher energy output was applied, the higher Ca/P ratio was observed. The higher Ca/P ratio in 60mJ group and 100mJ group was statistically significantly compared to the control group and the 30mJ group. These results suggest that Er:YAG laser irradiation on the periodontally diseased root surface could remove smear layer and increase the micro-hardness on root surface and Ca/P ratio which contribute to enhance the acid resistance of periodontally treated root surface.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.41 no.3
• /
• pp.161-169
• /
• 2017

The present study investigated the effect of the rib arrangement and a guide vane for enhancing internal cooling of the blade. Two types of rib arrangements were used in the first and second passage in parallel. Aspect ratio of the channel was 5 and a fixed Reynolds number based on hydraulic diameter was 10,000. The attack angle of rib was $60^{\circ}$, rib pitch-to-height ratio (p/e) was 10, and the rib height-to-hydraulic-diameter ratio ($e/D_h$) was 0.075. The effect of an interaction between Dean vortices and the secondary vortices from the first passage was observed. Overall, the attack angle of rib in the first passage was dominant factor to heat transfer and flow patterns in turning region. Also, the channel with a guide vane showed enhanced heat transfer at the tip surface with reducing flow separation and recirculation.

• The Korean Journal of Pain
• /
• v.14 no.2
• /
• pp.193-198
• /
• 2001

Background: Anterior atlantoaxial subluxation (AAS) is a frequent phenomenon in rheumatoid arthritis (RA). AAS compresses the C2 ganglion or nerve and is a cause of posterior neck pain or occipital headache. Methods: We selected RA patients that had developed posterior neck pain or occipital headache caused by AAS. AAS was diagnosed by an increase of ADI (atlantodental interval). A distance of 3 mm or more was considered significant. Patients with vertical subluxation or symptoms suggestive of myelopathy were excluded. Before C2 RF ganglionotomy, we proceeded with a C2 ganglion block or greater occipital nerve block used by local anesthetics. For C2 RF ganglionotomy, the patient was placed in the supine position on a fluoroscopic table. A 100 mm, 4 mm active tip electrode was chosen. Following sensory stimulation at 0.2 to 0.6 V, the lesion was performed at a temperature of $60^{\circ}C$ to $65^{\circ}C$ for 60 sec. We followed up the patient after 6 months later. Results: All cases were female and the average duration of RA was 8.5 years. The duration of posterior neck pain or occipital headache was 1-8 months. The average ADI was 4.2 mm and the McGregor index was 3.3 mm on the average. In all cases, the score on the 4 point Likert scale was 4 (pain free) during the follow-up period. Conclusions: We found that the occipital headache or posterior neck pain caused by AAS in rheumatoid arthritis patients was alleviated over a short term follow up. C2 RF ganglionotomy is suggested as an effective palliative treatment for AAS in RA patients.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.1
• /
• pp.1-10
• /
• 2005

An aerodynamic shape optimization technique has been developed for helicopter rotor blades in hover based on a continuous adjoint method on unstructured meshes. The Euler flow solver and the continuous adjoint sensitivity analysis were formulated on the rotating frame of reference for hovering rotor blades. In order to handle the repeated evaluation of the design cycle efficiently, the flow and adjoint solvers were parallelized using a domain decomposition strategy. A solution-adaptive mesh refinement technique was adopted for the accurate capturing of the tip vortex. Applications were made for the aerodynamic shape optimization of Caradonna-Tung rotor blades and UH60 rotor blades in hover. The results showed that the present method is an effective tool to determine optimum aerodynamic shapes of rotor blades requiring less torque while maintaining the desired thrust level.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.26 no.4
• /
• pp.16-26
• /
• 1989

Diffraction patterns of electromagnetic fields for the incidence of E-polarized plane wave on both interfaces of an arbitrary-angle dielect wedge are obtained by sum of geometric optics term and the edge diffracted fields. The diffraction coefficients of the edge diffracted fields are evaluated by employing the physical optics approximation and then correcting its error with the multipole line source at the dielectric edge. For the wedge angle $120^{circ}$, the incident angle $60^{circ}$, the relative dielectric constant of the dielectric wedge, 2, 5, and 10, and the observation distance from the tip of the wedge, 5 and 10 wavelength, the diffraction coefficients and the diffraction patterns corresponding to geometric optics, physical optics, and the solution corrected by the multipole line source are plotted, respectively. While the corrected solutions presented in this paper are valid only in the far-field region, these asymptotic solutions show to satisfy the boundary condition on the dielectric interfaces.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.2
• /
• pp.357-361
• /
• 2011

The terminal current in voltage driven systems is an essential role for characterizing the pattern of electric discharge such as corona, breakdown, etc. Until now, to evaluate this terminal current, Sato's equation has been widely used in areas of high voltage and plasma discharge. Basically Sato's equation was derived by using the energy balance equation and its final form described physical meaning explicitly. To give more general abilities in Sato's equation, we present a generalized approach by directly using the Poynting's theorem incorporating the finite element method. When the magnetic field effect or the time-dependent voltage source is considered, this generalized energy method can be easily applicable to those problems with any dielectric media such as gas, fluid, and solid. As an alternative approach, the integral Ohm's law resulting in small numerical errors has an ability to be applied to multi-port systems. To test the generalized energy method and integral Ohm's law, first, the results from two prosed methods were compared to those from Sato's approach and an analytic solution in parallel plane electrodes. After verification, the generalized method was applied to the tip-sphere electrodes for evaluating the terminal current with three carriers and the Fowler-Nordheim field emission condition. From these results, we concluded that the generalized energy method can be a consistent technique for evaluating the discharge current with various dielectric materials or large magnetic field.