• The Journal of the Acoustical Society of Korea
• /
• v.11 no.2
• /
• pp.28-37
• /
• 1992

In the study, the Acoustic transducer of a thin circular disc-type with PZT/Metal was manufactured. The 'tape casting method' was introduced to prepare the thin disc-type of piezoelectric ceramics. The acoustic characteristics of PZT/Metal acoustic transducer for piezoelectric buzzer and piezoelectric speaker etc. have been studied and analyzed. As a result, the sound pressure level (dB), in the range from -6dB to -14dB, increased with increasing the piezoelectric coeffeicient ($d_{31}$) of ceramics. The optimal conditions of the sound pressure characteristics of acoustic transducer were that the radius ratio(${\eta}$) of ceramics and metal plate is 0.7-0.8 and the thickness ratio(${\beta}$) is 1.0, and the value were -15~-165dB.

• Smart Structures and Systems
• /
• v.19 no.2
• /
• pp.163-179
• /
• 2017

The axisymmetric buckling delamination of the Piezoelectric/Metal/Piezoelectric (PZT/Metal/PZT) sandwich circular plate with interface penny-shaped cracks is investigated. The case is considered where open-circuit conditions with respect to the electrical displacement on the upper and lower surfaces, and short-circuit conditions with respect to the electrical potential on the lateral surface of the face layers are satisfied. It is assumed that the edge surfaces of the cracks have an infinitesimal rotationally symmetric initial imperfection and the development of this imperfection with rotationally symmetric compressive forces acting on the lateral surface of the plate is studied by employing the exact geometrically non-linear field equations and relations of electro-elasticity for piezoelectric materials. The sought values are presented in the power series form with respect to the small parameter which characterizes the degree of the initial imperfection. The zeroth and first approximations are used for investigation of stability loss and buckling delamination problems. It is established that the equations and relations related to the first approximation coincide with the corresponding ones of the three-dimensional linearized theory of stability of electro-elasticity for piezoelectric materials. The quantities related to the zeroth approximation are determined analytically, however the quantities related to the first approximation are determined numerically by employing Finite Element Method (FEM). Numerical results on the critical radial stresses acting in the layers of the plate are presented and discussed. In particular, it is established that the piezoelectricity of the face layer material causes an increase (a decrease) in the values of the critical compressive stress acting in the face (core) layer.

• Proceedings of the Acoustical Society of Korea Conference
• /
• spring
• /
• pp.275-278
• /
• 2000

In this study, the acoustic transducer of a thin circular disc-type with PZT/Metal was designed. The dielectric and piezoelectric properties of $0.5wt\%$ $MnO_2$ and NiO doped 0.1Pb($Mg_{1/3}$$Nb_{2/3}$)$O_3$-$0.45PbTiO_3$-$0.45PbZrO_3$ ceramics were investigated aiming at acoustic transducer applications. The vibration characteristics for the laminated circular plate was analyzed for the various thickness and diameter of the piezoceramic layer and metal layer. The acoustic characteristics which is radiated from the acoustic transducer within the finite space was simulated using the finite element method. It has been observed that the characteristics of the sound pressure ard impedance response calculated for the various models of the size and geometry of acoustic transducer.

• Proceedings of the IEEK Conference
• /
• 2007.07a
• /
• pp.337-338
• /
• 2007

The present paper proposes the method which improves a record and remaking efficiency of the optical pickup as applying the mirror where Phase Shift(PS) principle is applied to optical pickup. Plan to get a circularly polarized light quality above quality which is embodied through Existing Quater Wave Plate(QWP) and a function of total reflection mirror as applying PS mirror which integrates QWP with the function of the total reflection to optical pickup. In the present paper, embody circularly polarized light quality through applying PS mirror to optical pickup, and it through, plan to propose to come true the optimization of recording and remaking CD/DVD disc.

• Journal of Korean Neurosurgical Society
• /
• v.55 no.1
• /
• pp.12-17
• /
• 2014

Objective : Anterior cervical discectomy and fusion (ACDF) is often complicated by subsidence, pseudoarthrosis, kyphosis, and graft donor site morbidities. To decrease the occurrence of these complications, various types of cages have been developed. We designed this retrospective study to analyze and compare the efficacy and outcomes of ACDF using double cylindrical cages (DCC) (BK Medical, Seoul, Korea) versus an anterior cervical plating system with autogenous iliac crest grafts. Methods : Forty-eight patients were treated with autograft and plating (plate group), and 48 with DCC group from October 2007 to October 2011. We analyzed construct length, cervical lordotic curvarture, the thickness of the prevertebral soft tissue, segmental instability, and clinical outcomes. Results : There were no significant differences between the two groups with regard to the decrease in construct length or cervical lodortic curvature at the 3-, 6-, and 12-month follow-ups. The prevertebral soft tissue was thinner in the DCC group than the plate group immediately after surgery and at the 3-, 6-, and 12-month follow-ups. The difference in interspinous distance on flexion-extension was shorter in the plate group than the DCC group at the 3- and 6-month follow-ups. However, there was no significant difference in this distance between the two groups at the 12-month follow-up. Conclusion : A double cylindrical cage is a good alternative for fusion in patients with cervical degenerative diseases; the surgical method is relatively simple, allows good synostosis, has less associated prevertebral soft tissue swelling, and complications associated with autografting can be avoided.

• Korean journal of applied entomology
• /
• v.19 no.3 s.44
• /
• pp.163-168
• /
• 1980

The antibiotic bacterium JS7901, one of the eighty three antibiotic microorganisms which have been is elated in the surburbs of CheongJu-city, showed the most effective antimicrobial activities against test organisms, both bacteria and fungi. Among the different culture media Soytone Sugar medium was the most effective for growth and activity of the JS7901 antibiotic bacterium a against both Escherichia coli and Staphyllococcus aureus by the cylinder plate method. The higher the sugar content, was, the greater the antibiotic amount of substances of JS7901 were produced in the soytone sugar media. The antibiotic bacterium, JS7901 appeared to have a broad activity spectrum showing inhibition in Vitro against gram positive and negative bacteria and plant disease fungi. In general, the active substances were not transferred into organic solvents. Only a small portion of the activity was transferred into ethyl ether and was also adsorbed to active carbon when the cultured broth was also adsorbed to active carbon when the cultured broth was at $pH\;2.0\~4.0$. On adjusting at pH 8.0, the activity disappeared. The crude active substances could be obtained by means of vacuum drying method and still shelved strong activity. The dried active rake was solved by solvents and crystallized into various shapes. The active substances were developed on the silica gel plate in the solvent system of n-butanol-acetic acid-water(3 : 1 : 1) and gave 5 pinkish colored spots when sprayed with $0.2\%$ ninhydrine in ethanol. The upper 5th spot, which was the result of using disc plate method with Escherichia coli was the strongest of these spots.

• Korean Journal of Microbiology
• /
• v.5 no.2
• /
• pp.97-101
• /
• 1967

Up to the present time, there are only three methods by which we can obtain bacteria free crown gall tissue. According to some papers related to this field, the first method is based on the works of Braun(53') who maintained infected plants at 46-47'c for several days. But the method has a problem that very few plants can tolerate this temperature. The second method is based on the well known observation that old tumors appear to be bacteria free at least 1 or 2% of the explants. Also this method is known to us as laborious and time consuming. The third method is the one we were using that was attempting to kill the bacteria with bacteriacidal agent such as Antibiotics. In fact., it is reported that almost complete control of crown gall of tomato was obtained by Blanchard('51) when plants were grown in a nutrient containing Aureomycin(20${\mu}g$/ml) following needle puncture with the gall bacteria. We have been engaged in making the experiment by applying solution of Penicillin, Streptomycin and of Chloramphenicol(Succinate free) to find the strong bacteriacidal agent through the method of disc plate, and to confirm the effect of antimicrobial action through the method of plant tissue culture system without possible injury to the host plant. The result of this report is the fact the strongest bacteriacidal agent among the above three Antibiotics was Chloramphenicol(Succinate free 1000 p.p.m). and that there happened no injury to the tissue cultures in a White's 10X media containing 1000 p.p.m. of Chloramphenicol.

• Korean Journal of Food Science and Technology
• /
• v.29 no.5
• /
• pp.1028-1032
• /
• 1997

The strain No. 33, which produces cellulose-degrading enzyme, was isolated from soil. Yellow halo was identified when the culture supernatant of the strain was loaded onto agar plate containing 2.0% CMC using paper disc method. From scanning electron microscopic observation, the morphology of the stain was rod-shaped. For identification, several biochemical characteristics were tested, and this strain was identified to Bacillus sp. So, we named this strain as Bacillus sp. No. 33. The maximal growth was observed when the stain was cultured in the medium containing 1.0% glucose, 3.0% yeast extract, 0.5% $KH_2PO_4$, 0.02% $MgSO_4{\cdot}7H_2O$, pH 7.0 at $30^{\circ}C$ for 39 hours with shaking. The maximal enzyme production was accomplished using the medium containing 4.0% CMC, 2.0% yeast extract, 0.5% $KH_2PO_4$, 0.04% $MgSO_4{\cdot}7H_2O$, pH 7.0 at $30^{\circ}C$ for 42 hours with shaking.

• Journal of Yeungnam Medical Science
• /
• v.14 no.1
• /
• pp.209-219
• /
• 1997

Objectives: Anterior approach to achieve arthrodesis of the cervical spine has become a widely accepted and often-used approach since its earliest reports by Bailey and Badgley, Smith and Robinson and Cloward. However, anterior interbody fusion in the presence of the posterior instability may be complicated by the bone graft dislodgement, kyphotic defomity or nonunion. As an attemp to prevent this undesirable complication, additional methods such as skeletal traction, halo appratus or even posterior fusion has been utilized. Therefore, The cervical spine locking plate(CSLP) with the anterior intervertebral body bone grafting provide immediate cervical stabilization and widely successful in achieving fusion. Material and methods: This study analysed 14 patients who underwent a single anterior procedure and application of CSLP for the treatment of the cervical spinal disorder. Eleven patients were disc herniations and three patients were traumatic lesion. The average age of the patient was 47 years and the mean follow up periods was 20 months ranging from 13 to 27 months. Results: Ambulation was started 2nd day after the operation with the aid of the Philadelpia orthoses. Bone union was observed 13 cases on average 12 weeks after operation. The one case was nonunion with plate breakage without clinical symptom. Conclusion: Anterior fusion with CSLP are thought to be a safe and valuable method for treating cervical spine disorder.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.17 no.5
• /
• pp.353-360
• /
• 1984

As an effort to expand the utilization of mackerel which has been thought disadvantageous to processors due to the defects in bloody dark color of meat, high content of lipid, and low stability of protein, and to develope a new type of product, so called, preservative fish meat paste, the processing method was studied in which dielectric heating was applied by means of cooking, pasteurization, dehydration, and control of water activity. The principle of this method is based on that dielectric heating can initiate a rapid dispersion or displacement of moisture in the meat tissue so that the level of water acivity can be controlled by dehydration with hot air meanwhile the product is cooked, pasteurized, and texturized. And the product is finally heated with electric heaters and vacuum sealed to stabilize water activity and storage stability. In present paper, a formula for preparing the fish meat-stach paste, the conditions of dielectric heating and dehydration, shape and size of the product, and other parameters were tested to optimize the process operation. A formula of the fish meat-starch paste to provide proper textural properties and water activity was $10\%$ starch, $1.5\%$ salt, $3\%$ soybean, $0.6\%$ MSG, $2\%$ sucrose, and $3\%$ sorbitol against the weight of fish meat. A proper shape and size of the product to avoid foaming and case hardening during heating was sliced disc of 8 cm $diameter{\times}0.8$ cm thickness or $10{\times}10$ cm square plate with 1.0 cm thickness. The disc shape was recommended because it resulted more uniform heating, minimum foaming and case hardening. And it was also advantageous that disc was simply provided when the fish meat disc was stuffed in the same, solidified in boiling water for 2 to 3 minutes, and sliced. Condition of dielectric heating was critical to decide the levels of sterility, water activity, and textural property of the product. The temperature at the center of the meat disc slices was raised up to $95^{\circ}C$ in 1.5 minutes so that continuous exposure to microwave caused expanded tissue and hardening ending up with a higher water content. Heating for 5 to 6 minutes was adequate to yield the final water activity of 0.86 to 0.83(35 to $40\%$ moisture). It is important, however, that heating had to be done periodically, for instance, in the manner of 2.0, 1.5, 1.5, and 1.0 minute to give enough time to displace or evaporate moisture from the meat tissue. The product was dehydrated for 2 to 3 minutes by hot air of $60^{\circ}C$, 3 to 5m/sec and finally exposed to electric heaters for 5 to 6 minutes until the surface was roasted deep brown. These conditions of heating and dehydration resulted in a complete reduction of total plate count from an initial count of $5.3{\times}10^6/g$ to less than $3{\times}10^2/g$. General composition of the product was $40.1\%$ moisture, $20.8\%$ protein, $17.4\%$ lipid, $16.2\%$ carbohydrate, and $5.5\%$ ash. Textural properties revealed folding test AA, hardness 42, cohesiveness 0.53, toughness 4.6, and elasticity 0.8.