• The Journal of the Acoustical Society of Korea
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• v.35 no.3
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• pp.175-182
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• 2016

For application to several MHz photoacoustic imaging systems, a needle hydrophone was designed and fabricated by using PMN-PZT piezoelectric single crystal, and its characteristics were evaluated through comparison with a commercial PVDF(Polybinylidene Fluoride) hydrophone of which receiving sensitivity is known. The simulation using the KLM model results show that the peak receiving impulse response for $50{\Omega}$ terminating impedance of the fabricated hydrophone is -261.6 dB re $1V/{\mu}Pa$ and the frequency response is relatively flat over 2 ~ 12 MHz with fluctuation less than 5 dB. The measurement results using tone burst signals also show that it has higher (ave. 10.9 dB) sensitivity than the commercial hydrophone in 2 ~ 8 MHz, and the receiving sensitivity of $-255.8{\pm}2.8$ dB re $1V/{\mu}Pa$ was measured for the fabricated hydrophone. In addition, it is known that the photoacoustic signals and the image of a hair obtained by a mechanical scanned photoacoustic imaging system with the fabricated hydrophone were bigger and better than those obtained with the commercial hydrophone.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.12 no.3
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• pp.175-179
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• 1979

One of the major problems in tile activated sludge system has been difficulty in separating the microbial solids from the treated effluent and in returning them to the aeration tank. Another problem has been the digestion of the excess activated sludge. In constrast, it has not been difficult to separate the microbial solids from the treated effluent from the biological fixed-film systems(RBC process, Trickling Filter, FAST process). These systems have also featured less sludge production. Recently, it was proposed to experiment with the RESMAS process in order to eliminate the settling tank and sludge concentration facilities and to reduce the quantity of excess sludge for final disposal. The effluent quality could be predicted by .the concept of the maximum accumulation capacity. However, the hydraulic characteristics of the screen media in the RESMAS reactor were not dynamic. The object of the present study is to evalute the sludge accumulation rate and effluent quality prediction in the REMSMAS process designed in the dynamic hydraulic structure. This process can eliminate the final sedimentation tank and sludge concentration tank needed in the RBC, CMAS, Trickling Filter and FAST processes. Also, the effluent quality is desirable to compare with other processes. It appeared that the value of the sludge holding capacity was higher than those of the RESMAS and FAST processes, and the periods of the critical operating time were proportional to the substrate hydraulic loadings.

• The Journal of Society for e-Business Studies
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• v.22 no.1
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• pp.1-13
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• 2017

Though digital imaging devices such as smart phones, digital cameras and office scanners have improved significantly over the past years, they are seldom used for industrial application. This may be attributable to high level of quality and performance requirement for industrial application, but there lacks a test or an objective evaluation whether the upgraded performance of entry-level device is sufficiently enough to replace existing industrial equipments or not. If there exists an industrial application area where the applicability of entry-level equipment is proved by some objective tests, then companies will be able to reduce investment on expensive industrial equipment. In this study, applicability of entry-level digital devices for color difference discrimination of PVC (Polyvinyl chloride) color sheet is tested. By testing smart phone, digital camera, and office scanner for color difference discrimination, authors have found that office scanner shows consistent result with less measurement error. Additional experiment on comparing office scanner with industrial spectrophotometer has confirmed that there exists high correlation between the two devices' results. Based on this result, office scanner may be applicable to discriminate the color difference of PVC sheet instead of expensive industrial spectrophotometer if proper management criteria are established.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.4
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• pp.219-225
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• 2003

Purpose: Platelet Rich Plasma(PRP) application is increasing with sinus inlay bone graft, but there is few research with radiographic ananlysis on effect of PRP in maxillary sinus. The author investigated the amount of bony changes of maxillary sinus for dental implantation among the patients with maxillary inlay graft. Materials and Methods: With 10 patients who were treated with sinus inlay autologous bone grafting combined with PRP technique, and with 5 patients who were treated with sinus inlay grafting only without PRP, the panoramic radiographys which were taken at preoperation, immediate postoperation, 3months postoperation, and 4 months postoperation(a month after dental implantation)periods were analysed. The films had been scanned, and then proceeded throughout image analysis system. The bone density of maxillary grafted sites was compared with adjacent tooth enamel density and remeasured according to density luminosity of each film. The density changes on PRP group and bone graft only group were analysed with non-parameteric statistics method. Results: In PRP combined patients group, bone density on postoperation periods was increased totally. The remarkable enhanced change of bone density was observed on 3 months postoperation period, thereafter the increasing rate was slightly reduced. In only bone graft patients group, bone density on postoperation periods was also increased compared with preoperation period, but the bone density of 4 months postoperation period was decreased compared with 3 months postoperation period. The amount of bone density on PRP group was significantly changed according to periods in contrast to bone graft only group. Conclusion: The bone density on PRP group was remarkably increased at 3 months postoperation compared to bone graft only group and it was seemed to be associated with more new bone formation, less grafted bone resorption at bone grafted sites with PRP.

• Journal of the Korean Society of Radiology
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• v.5 no.6
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• pp.369-375
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• 2011

In dental radiography, panoramic views cause distortion and thus may bring about inaccurate results in the process of quantitative analysis. In this connection, there has recently been an increasing use of cone beam computed tomography (CBCT) that is known to provide high-resolution images and positional information. In this study, a dental computed tomography unit, 'DCT-90-P IMPLAGRAPHY (Vatech, Korea)', was applied to 20 patients for 24 seconds respectively, with a tube voltage of 85kVp and a tube current of 7mA. The data of CBCT were three-dimensionally reconstructed by use of a computer program, and were histomorphometrically analyzed. The results showed that the diameter of mandibular canal is less distorted at a certain inclination of the mandibular body. The image tends to seem more distended in proportion to the distance between the subject and film. Also, the image tends to be affected according as it is out of focus. In conclusion, it requires that the image should be reconstructed in light of anatomic position and structure.

• Journal of the Microelectronics and Packaging Society
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• v.6 no.2
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• pp.37-43
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• 1999

Modules of the system that requires large capacity and high-speed information processing are implemented in the form of MCM that allows high-speed data processing, high density circuit integration and widely applied to such fields as ATM, GPS and PCS. Hence we developed the ATM switching module that is consisted of three chips and 2.48 Gbps data throughput, in the form of 10 multi-layer by Cu/Photo-BCB and 491pin PBGA which size is $48 \times 48 \textrm {mm}^2$. hnologies required for the development of the MCM includes extracting parameters for designing the substrate/package through the interconnect characterization to implement the high-speed characteristics, thermal management at the high-density MCM, and the generation of the testability that is one of the most difficult issues for developing the MCM. For the development of the ATM Switching MCM, we extracted signaling delay, via characteristics and crosstalk parameters through the interconnect characterization on the MCM-D. For the thermal management of 15.6 Watt under the high-density structure, we carried out the thermal analysis. formed 1.108 thermal vias through the substrate, and performed heat-proofing processing for the entire package so that it can keep the temperature less than $85^{\circ}C$. Lastly, in order to ensure the testability, we verified the substrate through fine pitch probing and applied the Boundary Scan Test (BST) for verifying the complex packaging/assembling processes, through which we developed an efficient and cost-effective product.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.4
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• pp.18-25
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• 2000

A two-color particle image velocimetry (PIV) has been developed for measuring two dimensional velocity flowfields and applied to a Mach 2.0 supersonic nozzle. This technique is similar to a single-color PIV technique except that two different color laser beams are used to solve the directional ambiguity problem. A green-color laser sheet (532 nm: 2nd harmonic beam of YAG laser) and a red-color laser sheet (619 nm: output beam from YAG pumped Dye laser using Rhodamine 640) are employed to illuminate the seeded particles. A high resolution (3060${\times}$2036) digital color CCD camera is used to record the particle positions. This system eliminates the photographic-film processing time and subsequent digitization time as well as the complexities associated with conventional image shifting techniques for solving directional ambiguity problem. The two-color PIV also has the advantage that velocity distributions in high speed flowfields can be measured simply and accurately by varying the time interval between two different laser beams due to its high signal-to-noise ratio and thereby less requirement of panicle pair numbers for a velocity vector in one interrogation spot. The velocity distribution in the Mach 2.0 supersonic nozzle has been measured and the over-expanded shock cell structure can be predicted by the strain rate field. These results are compared and analyzed with the schlieren photograph for the velocity distributions and shock location.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.4
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• pp.329-334
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• 1992

In order to obtain basic informations on establishment of culture system for Cassia tora L. in the southern part of Korea, under vinyl mulching and non mulching conditions, the characters of growth and yield following the difference of fertilization quantity were investigated. All characters, stem length, stem diameter, number of branches, number of pods per plant, pod length, and number of grains per pod, etc., were excellent under the vinyl mulching condition, and of these growth characters, stem diameter, number of pods per plant, and number of grains per pod, etc. were most excellent in the district of N-P$_2$O$_{5}$-K$_2$O=8-6-6Kg /10a. Weight of 1000 grains and seed yield were also high under the vinyl mulching condition, and starting form the district of fertilization quantity N- P$_2$O$_{5}$-K$_2$O=8-6-6Kg /10a, the districts of increasing or decreasing fertilizer tended to be less yield. Also under the vinyl mulching and non mulching, the dispersive analyses of useful characters following the difference of fertilization quantity, were acknowledged to be worth of attention.

• Progress in Medical Physics
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• v.16 no.2
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• pp.89-96
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• 2005

In this study, we investigated the effect of time gating threshold on the delivered dose at a organ with internal motion by respiration. Generally, the internal organs have minimum motion at exhalation during normal breathing. Therefore to compare the dose distribution time gating threshold, in this paper, was determined as the moving region of target during 1 sec at the initial position of exhalation. The irradiated fields were then delivered under three conditions; 1) non-moving target 2) existence of the moving target in the region of threshold (1sec), 3) existence of the moving target region out of threshold (1.4 sec, 2 sec). And each of conditions was described by the moving phantom system. It was compared with the dose distributions of three conditions using film dosimetry. Although the treatment time increased when the dose distributions was obtained by the internal motion to consider the TGT, it could be obtained more exact dose distribution than in the treatment field that didn't consider the internal motion. And it could be reduced the unnecessary dose at the penumbra region. When we set up 1.4 sec of threshold, to reduce the treatment time, it could not be obtained less effective dose distribution than 1 sec of threshold. Namely, although the treatment time reduce, the much dose was distributed out of the treatment region. Actually when it is treated the moving organ, it would rather measure internal motion and external motion of the moving organ than mathematical method. If it could be analyzed the correlation of the internal and external motion, the treatment scores would be improved.

• Radiation Oncology Journal
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• v.14 no.1
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• pp.77-85
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• 1996

Purpose : Multileaf collimator(MLC) is very suitable tool for conformal radio-therapy and commissioning measurements for a multileaf collimator installed on a dual energy accelerator with 6 and 10MV photons are required, For modeling the collimator with treament planning software, detailed dosimetric characterization of the multileaf collimator including the penumbra width, leaf transmission between leaf leakage and localization of the leaf ends and sides is an essential requirement. materials and Methods : Measurement of characteristic data of the MLC with 26 pair block leaves installed on CLINAC 2100C linear accelerator was performed. Low sensitive radiographic film(X-omatV) was used for the penumbra measurement and separate experiments using radiographic film and thermoluminescent dosimeters were performed to verify the dose distribution, Measured films were analized with a photodensitometer of WP700i scanner. Results : For 6 & 10 MV x-ray energies, approximately $2.0\%$ of photons incident on the multileaf collimator were transmitted and an additional $0.5\%$ leakage occurs between the leaves. Localizing the physical end of the leaves showed less than 1mm deviation from the $50\%$ decrement line and this difference is attributed to the curved shaped end on the leaves One side of a sin히e leaf corresponded to the $50\%$ decrement line, but the opposite face was aligned with a lower value. This difference is due to the tongue and groove used to decrease between leaf leakage. Alignment of the leaves to form a straight edge resulted larger penumbra at far position from isocenter as compare with divergent alloy blocks. When the MLC edge is stepped by sloping field, the isodose lines follow the leaf pattern and Produce scalloping isodose curves in tissue. The effective penumbra by 45 degree stepped MLC is about 10mm at 10cm depth for 6MV x-ray. The difference of effective penumbra in deep tissue between MLC and divergent alloy blocks is small (5mm). Conclusion : Using the characteristic data of MLC, the MLC has the clinlical acceptability and suitability for 3-D conformal radiotherapy except small field size.