• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.5
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• pp.33-40
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• 2004

In this paper, we constructs face database by using wavelet comparison, and compare face recognition rate by using principle component analysis (Principal Component Analysis : PCA) algorithm. General face recognition method constructs database, and do face recognition by using normalized size. Proposed method changes image of normalized size (92${\times}$112) to 1 step, 2 step, 3 steps to wavelet compression and construct database. Input image did compression by wavelet and a face recognition experiment by PCA algorithm. As well as method that is proposed through an experiment reduces existing face image's information, the processing speed improved. Also, original image of proposed method showed recognition rate about 99.05%, 1 step 99.05%, 2 step 98.93%, 3 steps 98.54%, and showed that is possible to do face recognition constructing face database of large quantity.

• Journal of Pharmaceutical Investigation
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• v.24 no.3
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• pp.139-144
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• 1994

The effect of some formulation variables on the release rate of famotidine, a $H_2$ receptor antagonist, from cellulose matrices containing hydroxypropylcellulose (HPC) in different ratios and types was investigated. The effects of tablet shape and compression pressure on dissolution rate of famotidine were studied. And the effect of the pH of dissolution media was also studied. Increase in the ratio of polymer to drug decreased the release rate of famotidine. Increase of the polymer viscosity also decreased the release rate. The release rate of famotidine was dependent on the pH of dissolution media. The release rate of drug was not much dependent on the compression pressure but dependent on the tablet shape and/or surface area. Consequently, the release rate of famotidine can be modified by changing the HPC contents, types of polymers with different viscosity grades or using appropriate fillers.

• Journal of Mechanical Science and Technology
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• v.18 no.8
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• pp.1451-1460
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• 2004

A two-stroke Schnurle-type gasoline engine was modified to enable compression-ignition in both the port fuel injection and the in-cylinder direct injection. Using the engine, examinations of compression-ignition operation and engine performance tests were carried out. The amount of the residual gas and the in-cylinder mixture conditions were controlled by varying the valve angle rate of the exhaust valve (VAR) and the injection timing for direct injection conditions. It was found that the direct injection system is superior to the port injection system in terms of exhaust gas emissions and thermal efficiency, and that almost the same operational region of compression-ignition at medium speeds and loads was attained. Some interesting combustion characteristics, such as a shorter combustion period in higher engine speed conditions, and factors for the onset of compression-ignition were also examined.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.193-195
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• 2009

In this paper, we propose an effective compression method for electrocardiogram(ECG) signals. 1-D ECG signals are reconstructed to 2-D ECG data by period and complexity sorting schemes with image compression techniques to Increase inter and intra-beat correlation. The proposed method added block division and mean-period normalization techniques on top of conventional 2-D data ECG compression methods. JPEG 2000 is chosen for compression of 2-D ECG data. Standard MIT-BIH arrhythmia database is used for evaluation and experiment. The results show that the proposed method outperforms compared to the most recent literature especially in case of high compression rate.

• The Korean Journal of Pain
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• v.18 no.2
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• pp.142-145
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• 2005

Background: Vertebroplasty that is performed in the upper and middle thoracic spine presents technical challenges that are different from those in the lower thoracic or lumbar region due to the small pedicle size and angular severity for thoracic kyphosis. We report the results of percutaneous vertebroplasty and review its effectiveness in treating intractable osteoporotic compression fractures in the upper and middle thoracic spine. Methods: Patients who underwent vertebroplasty due to painful osteoporotic compression fractures at T3 T8 were retrospectively analyzed. The compression rate, volume of injected cement, clinical outcome (VAS score) and complications were analyzed. Results: Forty-three vertebral bodies from 41 patients (32 females and 9 males, age from 64 to 78 years old) underwent vertebroplasty. The mean compression rate improved from 35% to 17%. Bipedicular injections of bone cement were performed at 3 levels of 2 patients, and unipedicular injections were performed in 40 levels of 39 patients. The mean VAS score prior to surgery was 7.7, which improved to 2.4 within 48 hours after surgery, and the mean VAS score after 6 months was 1.5, which was significantly lower. All patients recovered uneventfully, and the neurological examination revealed no deficits. Cement leakage to the adjacent disc (9 levels) and paravertebral soft tissues (10 levels) developed. However, there were no significant complications related to the procedure such as a pneumothorax or pulmonary embolism. Conclusions: Transpedicular vertebroplasty is a safe and effective treatment for the upper and middle thoracic regions, and has a low complication rate.

• Journal of Ocean Engineering and Technology
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• v.26 no.6
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• pp.19-26
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• 2012

Recently the world has been suffering from difficulties related to the demand and supply of energy due to the democratic movements sweeping across the Middle East. Consequently, many have turned their attention to never-developed extreme regions such as the polar lands or deep sea, which contain many underground resources. This research investigated the strength and initial elastic modulus values of eternally frozen ground through a uniaxial compression test and indirect tensile test using frozen artificial soil specimens. To ensure accurate test results, a sandymud mixture of standard Jumunjin sand and kaolinite (20% in weight) was used for the specimens in these laboratory tests. Specimen were prepared by varying the water content ratio (7%, 15%, and 20%). Then, the variation in the strength value, depending on the water content, was observed. This research also established three kinds of environments under freezing temperatures of $-5^{\circ}C$, $-10^{\circ}C$, and $-15^{\circ}C$. Then, the variation in the strength value was observed, depending on the freezing environment. In addition, the tests divided the loading rate into 6 phases and observed the variation in the stress-strain ratio, depending on the loading rate. The test data showed that a lower freezing temperature resulted in a larger strength value. An increase in the ice content in the specimen with the increase in the water content ratio influenced the strength value of the specimen. A faster load rate had a greater influence on the uniaxial compression and indirect tensile strengths of a frozen specimen and produced a different strength engineering property through the initial tangential modulus of elasticity. Finally, the long-term strength under a constant water content ratio and freezing temperature was checked by producing stress-strain ratio curves depending on the loading rate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.5
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• pp.447-454
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• 2009

Rate-independent crystal plasticity model suffers from the non-uniqueness of activated slip systems and the determination of the shear slip rates on the active slip systems. In this paper, a time-integration algorithm which circumvents the problem of the multiplicity of the slip systems was developed and implemented into the user subroutine VUMAT of a commercial finite element program ABAQUS. The magnitude of the slip shears on the active slip systems in f.c.c Cu single crystal aligned with the specific crystallographic orientation was investigated to validate our solution procedure. Also, texture developments under various deformation modes such as simple compression, simple tension and plane strain compression were compared with the results of the rate-dependent model by using the rate-independent crystal plasticity model. The computation time employing the rate-independent model is much more reduced than the those of the rate-dependent model.

• Journal of Korean Neurosurgical Society
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• v.62 no.5
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• pp.594-602
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• 2019

Objective : Although surgical intervention, such as percutaneous vertebroplasty (PVP), is the standard treatment for osteoporotic vertebral compression fractures (OVCFs), its effectiveness and safety are unclear. Therefore, this study compared the safety and efficacy of conservative treatment with that of PVP for acute OVCFs. Methods : Patients with single-level OVCFs who were treated conservatively with a transdermal fentanyl patch (TFP) or with PVP between March 2013 and December 2017 and followed-up for more than 1 year were retrospectively evaluated. Patients with pathologic fractures, fractures of more than two columns, or a history of PVP were excluded. Clinical outcomes (visual analog scale [VAS] scores) and radiographic factors were evaluated, including changes in the compression rate of the corresponding vertebral body at onset and after 12 months, sagittal Cobb angle at onset and after 6 and 12 months, and the incidence of adjacent compression fractures. Results : Of the 131 patients evaluated, 75 were treated conservatively using TFPs and 56 underwent PVP. We divided the patients into TFP and PVP groups. Their baseline characteristics (including sex, level of fracture, and bone mineral density T-scores) were similar, but the TFP group was significantly younger. The overall VAS score for pain showed a greater decrease during the first month (1 week after PVP) in the PVP group but remained similar in the two groups thereafter. The compression rate after 12 months increased in the TFP group but decreased in the PVP group. Five patients in the PVP group, but none in the TFP group, experienced adjacent compression fractures within 12 months. Conclusion : We compared clinical and radiological outcomes between the TFP and PVP groups. The immediate pain reduction effect was superior in the PVP group, but the final clinical outcome was similar. Although the PVP group had a better-preserved compression rate than the TFP group for 1 year, the development of adjacent fractures was significantly higher. Although TFPs seemed to be beneficial in reducing the failure rate of conservative treatment, the possibility of side effects (22.6%, 17 out of 75 patients, in this study) should be carefully monitored.

• Journal of the Korean Institute of Gas
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• v.27 no.2
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• pp.1-6
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• 2023

PE piping, which has advantages in terms of construction convenience and economy, is widely used for underground burial in the domestic urban gas field. These PE pipes use squeeze-off in many sites to block gas flow during maintenance and repair work. Squeeze-off refers to a method of compressing a PE pipe to block fluid flow, and damage may occur due to the nature of construction in which the pipe is deformed by physical force. In order to prevent damage to PE pipes due to squeeze-off, the main points to be reflected in the squeeze-off operation procedures such as proper compression range, use pressure, and diameter were derived through damage assessment and confidential test according to the compression rate. The compression experiment for PE pipe damage assessment was conducted while changing the compression rate (20%~40%), the pressure of use (2.8 kPa, 25 kPa, 70 kPa), and the pipe diameters (63 mm, 90 mm, 110 mm). As a result of damage assessment according to the compression rate, damage occurred in pipes with compression rates of 45%(110mm) and 73%(63mm), which are for analyzing the effect of excessive compression. In addition, the leakage test was conducted using Ar(argon) during the squeeze-off, and as a result of the experiment, leakage occurred under the conditions of 70kPa and 110mm of pipe. As a result of this study, it was confirmed that squeeze-off for airtightness should be carried out in pipes within a range not exceeding 25 kPa and 90 mm pipes, and the appropriate compression rate to prevent damage to PE pipes is 30%.

• Korean Journal of Agricultural Science
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• v.17 no.2
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• pp.95-101
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• 1990

In order to investigate the influence of unconfined compression strength on undisturbed cohesive soil, the unconfined compression test were carried out on the basis of various size of specimen and compression rate. The result of these experiments were summarized as follows. 1. As the section area of specimen increased. the unconfined compression strength was decreased. 2. As the ratio of height and diameter of specimen increased, the unconfined compression strength was decreased. 3. The unconfined compression strength was increased by 3%, but in values over the 3% was decrease. 4. As the compression rate increased. the modulus of deformation was increased.