• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.371-379
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• 2004

Soil investigation data at 7 different locations around Honam costal region were analyzed and experimental correlations between soil properties and parameters of soft clay were presented. Most soils were classified as CL and CH by the Unified Soil Classification System and were unstable structurally because the water contents were generally greater than the liquid limits. The compression index has good correlations with water content, liquid limit and initial void ratio. The trend of these correlations were similar to the Skempton equation Cc = 0.009(LL -10) and other studies for Korean soft clays but the constants were small different. The slope of these correlations for Honam costal region were slightly greater than those for Kyunggi costal region and Kyungnam costal region. The correlation coefficient (R) between the liquid limit and the plastic index is 0.93. It is seen that not only the water content and the liquid limit but also the water content and the initial void ratio are correlate, therefore the experimental equations were presented for the practical purpose.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.2 s.302
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• pp.49-58
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• 2005

In this paper, we proposed a blind watermarking algerian to use characteristics of a scalar quantizer which is the recommended in the JPEG2000 and JPEG. The proposed algorithm shifts a quantization index according to the value of each watermark bit to prevent losing the watermark information during the compression by quantization. Therefore, the watermark is embedded during the process of quantization, not an additional process for watermarking, and is adaptively applied as a assigned quantizer according application areas. Before embedding process, a LFSR(Linear feedback shift register) rearranged the watermark for the security of the watermark itself and in the embedding process, a LFSR is used to hide the watermarking positions. Therefore the embedded watermark can he extracted by only the owner who knows the initial value of LFSR without the original image. The visual recognizable pattern such as a binary image was used as the watermark. The experimental results showed that the proposed algerian satisfies the robustness and imperceptibility corresponding to the major requirement of watermarking. The results showed the largest error rate to be $5.7\%$ for attack. The experimental result which compares the proposed algorithm with the Mohamed algorithm showed that the proposed algorithm was better than it, exactly $4\~5$ times for the attacks of JPEG and JPEG2000.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.4
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• pp.31-41
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• 2012

The law enforcement agencies in the worldwide are confiscating or retaining computer systems involved in a crime/civil case, if there are any, at the preliminary investigation stage, even though the case does not involve a cyber-crime. They are collecting digital evidences from the suspects's systems and using them in the essential investigation procedure. It requires much time, though, to collect, duplicate and analyze disk images in general crime cases, especially in cases in which rapid response must be taken such as kidnapping and murder cases. The enterprise forensics, moreover, it is impossible to acquire and duplicate hard disk drives in mass storage server, database server and cloud environments. Therefore, it is efficient and effective to selectively collect only traces of the behavior of the user activities on operating systems or particular files in focus of triage investigation. On the other hand, if we acquire essential digital evidences from target computer, it is not forensically sound to collect just files. We need to use standard digital evidence container from various sources to prove integrity and probative of evidence. In this article, we describe a new digital evidence container, we called Xebeg, which is easily able to preserve collected digital evidences selectively for using general technology such as XML and PKZIP compression technology, which is satisfied with generality, integrity, unification, scalability and security.

• The Journal of Korean Academy of Prosthodontics
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• v.31 no.2
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• pp.219-235
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• 1993

To determine the compatibilities of soft liming materials with denture cleansers by measuring the flexibility and elasticity and investigating the surface changes, 4 self-curing acrylic resin soft lining materials and 1 heat-curing silicone soft lining material were evaluated. 3mm thick x 20mm diameter discs of soft lining materials were individually bonded to a hard acrylic resin base as per manufacturers’instructions. Using an Instron universal testing machine, a static stress of $2kg/cm^2$ was applied for 30secs., the strain in compression was measured, giving an indication of the material’s flexibility. Elastic recovery was measured at 10secs. After removal of stress. Surface changes were investigated with Stereomicroscope. Then the specimens were immersed in 4alkaline peroxide denture cleansers and water as control group, tests were carried out at 1 day, 2 days, 7 days, 14 days and 30 days. The results were as follows : 1. Alkaline peroxide denture cleansers caused considerable porosity on the surface of selfcuring acrylic resin soft lining materials, and the most affected by the cleansers were Viscogel, Coe-Soft, Coe-Comfort, Lynal, in that order. 2. There was significant difference in flexibility between each soft lining material except for Coe-Comfort and Visco-gel, and every soft lining material was significant difference in elasticity. Especially Molloplast-B and Lynal were less flexible and more elastic than other soft lining materials(p<0.05). 3. The denture cleansers increased the flexibility and elasticity of the soft lining materials compared with control group(p<0.05), and Denalan, Polident, Kleenite, Efferdent affected the soft lining materials in that order. 4. There was significant difference in flexibility between each denture cleanser except for Denalan and Polident(p<0.05). Though Denalan and Polident, Denalan and Kleenite did not show significant difference in elasticity, other denture cleansers showed significant difference among each other(p<0.05). 5. Clinically Coe-Comfort, Coe-Soft and Visco-gel were incompatible with alkaline peroxide denture cleansers, and Lynal would be used within only 2 weeks. But Molloplast-B was compatible with alkaline peroxide denture cleansers.

• Korean Journal of Materials Research
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• v.25 no.2
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• pp.75-80
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• 2015

The carbon dioxide($CO_2$) released while producing building materials is substantial and has been targeted as a leading contributor to global climate change. One of the most typical method to reducing $CO_2$ for building materials is the addition of slag and fly ash, like pozzolan material, while another method is reducing $CO_2$ production by carbon negative cement development. The MgO-based cement was from the low-temperature calcination of magnesite required less energy and emitted less $CO_2$ than the manufacturing of Portland cements. It is also believed that adding reactive MgO to Portland-pozzolan cements could improve their performance and also increase their capacity to absorb atmospheric $CO_2$. In this study, the basic research for magnesia cement using $MgCO_3$ and magnesium silicate ore (serpentine) as main starting materials, as well as silica fume, fly ash and blast furnace slag for the mineral admixture, were carried out for industrial waste material recycling. In order to increase the hydration activity, $MgCl_2$ was also added. To improve hydration activity, $MgCO_3$ and serpentinite were fired at $700^{\circ}C$ and autoclave treatment was conducted. In the case of $MgCO_3$ as starting material, hydration activity was the highest at firing temperature of $700^{\circ}C$. This $MgCO_3$ was completely transferred to MgO after firing. This occurred after the hydration reaction with water MgO was transferred completely to $Mg(OH)_2$ as a hydration product. In the case of using only $MgCO_3$, the compressive strength was 3.5MPa at 28 days. The addition of silica fume enhanced compressive strength to 5.5 MPa. In the composition of $MgCO_3$-serpentine, the addition of pozzolanic materials such as silica fume increased the compression strength. In particular, the addition of $MgCl_2$ compressive strength was increased to 80 MPa.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.12
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• pp.894-906
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• 2006

There are many difficulties to develop a mobile contents due to many constraints on mobile environments. It is difficult to make a good mobile contents with only visual reduction of existing contents on wire Internet. Therefore, it is essential to devise the data representation and to develop the authoring tool to meet the needs of the mobile contents market. We suggest the compact mobile contents to learn Chinese characters and developed its authoring tool. The animation which our system produces is realistic as if someone writes letters with pen or brush. Moreover, our authoring tool makes a user generate a Chinese character animation easily and rapidly although she or he has not many knowledge in computer graphics, mobile programming or Chinese characters. The method to generate the stroke animation is following: We take basic character shape information represented with several contours from TTF(TrueType Font) and get the information for the stroke segmentation and stroke ordering from simple user input. And then, we decompose whole character shape into some strokes by using polygonal approximation technique. Next, the stroke animation for each stroke is automatically generated by the scan line algorithm ordered by the stroke direction. Finally, the ordered scan lines are compressed into some integers by reducing coordinate redundancy As a result, the stroke animation of our system is even smaller than GIF animation. Our method can be extended to rendering and animation of Hangul or general 2D shape based on vector graphics. We have the plan to find the method to automate the stroke segmentation and ordering without user input.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.4
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• pp.172-179
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• 2014

HEVC (High Efficiency Video Coding) fine-tuned many existing coding tools and adopted also many new coding techniques. As a result, HEVC has accomplished about 2 times of compression efficiency enhancement compared to the existing video coding standard of H.264/AVC. One of the newly adopted tools in HEVC is the transform skip scheme which performs quantization without transform. This technique improves coding efficiency especially with computer-generated images. However, the unavailability of global or local properties of general video signals demands encoder to decide whether performing transform or not for each TU (Transform Unit). The necessity of computing rate-distortion costs for this decision is one reason to increase encoder complexity. In this paper, a fast transform skip mode decision method is proposed, which is based on the fast decision of rate-distortion cost calculation for transform skip mode, by considering frequency characteristics of residual signal. The proposed method can reduce $4{\times}4$ TU encoding time by about 27.1% with only about 0.03% consequential decrement in BDBR.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.2
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• pp.401-412
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• 1997

There has been many researches aimed at reinforcing the strength of resin, and these have led to the development and use of numerous materials in recent years. A case in point, is the recent development of plasma-treated polyethylene fiber which has been used mainly in fixed provisional restoration to reduce the incidence of fractures. This study aims at assessing whether plasma-treated polyethylene fiber as applied to composite resin is effective in increasing the flexural strength and how applied portions affect this. Twenty-four applied and eight unapplied composite resin bars were fabricated. Twenty-four applied specimens were divided into three groups. Plasma treated polyethylene fiber was applied to the groups each with different portions of composite resin. In the first group, plasma-treated polyethylene fiber was not applied. In the second group, fiber was applied to the compression side of composite resin. Fiber was applied to the tension side in the third group, while fiber was embedded in the tension side of the composite resin in the fourth group. Each specimen was tested by use of a three-point bending strength test with an instron testing machine, and the flexural strength was calculated. The following results were obtained. : 1. Under the conditions of this study, the third and fourth groups demonstrated a statistically greater flexural strength compared to the first and second groups. 2. But there was no statistically significant difference, not only between the first group and the second group, but also between the third group and the fourth group. Taken together, it can be concluded that plasma-treated polyethylene fiber applied to composite resin is an effective method in increasing flexural strength, and the best way of increasing the flexural strength is by application of plasma-treated polyethylene fiber to the tension side, or the embedding of same in composite resin. It must be mentioned however that this test used a static single-load test method. This method determined the maximum stresses that could be tolerated, but this might not be valid where the prediction of clinical failure is concerned. In order therefore to clinically utilize plasma-treated polyethylene fiber to reinforce the composite resin, it is suggested that a further study which considers the various loads be undertaken.

• Journal of Biomedical Engineering Research
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• v.23 no.6
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• pp.451-458
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• 2002

Osteoporosis is a systemic skeletal disease caused by low bone mass and the decrease of bone density in the microstructure of trabecular bone. Drug therapy(PTH Parathyroid hormone) may increase the trabecular thickness and thus bone strength. Vertebroplasty is a minimally invasive surgery foy the treatment of osteoporotic vertebral compression fracture. This Procedure includes Puncturing vertebrae and filling with Polymethylmethacrylate(PMMA). Although altering recommended monomer-to-Powder ratio affects material properties of bone cement, clinicians commonly alter the mixture ratio to decrease viscosity and increase the working time. The Purposes of this study were to analyze the effect of 4he monomer-to-powder ratio on the mechanical characteristics of trabecular. In this paper, the finite element model of human vertebral trabecualr bone was developed by modified Voronoi diagram, to analyze the relative effect of hormone therapy and vertebroplasty at the treatment of osteoporotic vertebrae. Trabeuclar bone models for vertebroplasty with varied monomer-to-Powder ratio(0.40∼1.07 ㎖/g) were analyzed. Effective modulus and strength of bone cement-treated models were approximately 60% of those of intact models and these are almost twice the values of hormone-treated models. The bone cement models with the ratio of 0.53㎖/g have the maximum modulus and strength. For the ratio of 1.07㎖/g, the modulus and strength were minimum(42% and 49% respectively) but these were greater than those for drug therapy. This study shows that bone cement treatment is more effective than drug therapy. It is found that in vertebroplasty, using a monomer-to-powder ratio different from that recommended by manufacturer nay significantly not only reduce the cement's material Properties but also deteriorate the mechanical characteristics of osteoporotic vertebrae.

• Archives of Plastic Surgery
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• v.42 no.5
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• pp.552-558
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• 2015

Background The Klippel-Trenaunay syndrome (KTS) is characterized by three clinical features, namely cutaneous capillary malformations, venous malformations, and soft tissue and/or bony hypertrophy of the extremities. The varied manifestations are attributed to the unpredictable clinical nature and prognosis of the syndrome. To elucidate the clinical characteristics of this disease, we reviewed a relatively large number of KTS patients who presented to our vascular anomalies center. Methods We conducted a retrospective study with 19 patients who were diagnosed with KTS and treated in our vascular anomalies clinic between 2003 and 2014, and examined their demographic characteristics, their clinical features, and the treatments administered. Results The sex distribution was balanced, with 9 (47%) males and 10 (53%) females. The mean follow-up period was 4.1 years (range, 7 months-9 years). Most of the patients received conservative treatments such as medication or physiotherapy. Compression therapies such as wearing of elastic garments/bandages were also administered, and surgical interventions were considered only when the patients became excessively symptomatic. Other treatments included laser therapy and sclerotherapy, and all the treatments were adjusted according to each case, tailored to the conditions of the individual patients. Conclusions KTS is an extremely rare, multifactorial disorder that induces widely varied symptoms. Because of this unique feature, plastic surgeons, when not careful, tend to attach a one-sided importance to typical symptoms such as limb hypertrophy or capillary malformation and thus overlook other symptoms and clinical features. KTS can be suspected in all infants who show capillary malformations or limb hypertrophy and require a multi-disciplinary approach for comprehensive management.