• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.6
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• pp.35-40
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• 2012

This paper has proposed a 3~5 GHz IR-UWB low power transmitter for range detection application. Proposed transmitter which has been implemented in a $0.13{\mu}m$ CMOS technology is all digital circuit that consist of simple digital logic. this feature insure low complexity and low power consumption. In addition, center frequency can be changed by adopting voltage controlled delay cell for avoiding existing another radio frequency in UWB low band. Proposed circuit consume only 10pJ/b from 1.2 V supply voltage. The simulation results show 3.3~4.3 GHz center frequency controllability, -51 dBm/MHz maximum output power and is satisfied with FCC regulation.

• Magazine of the Korea Concrete Institute
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• v.9 no.2
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• pp.167-177
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• 1997

In thtx design of ductile moment -1csist1ng frnmcls (DMRFs) f'ollow~ng the. stlong columnweakbeam design philosophy, it is desirable that the joint and column remain essentiallyelastic in order to insure proper energy dissipation and lateral stability of the structure.Thv joint has been identifid as the "weak link: in DMRFs because any stiffness orstrength deterioration in this region can lead to substantial drifts and the possibility ofcollapse due to t'-delta effects. h3oreove1.. the tngintw is faced with the difficult task ofdetailing an element whose size is determined by theframing members, but \vhich mustresist a set of loads very different from those used in the design of the beams and columns.Four 3 -scale beam-column-slab joint assemblies were designed according to existing cod\ulcornerrequirements of' ACI 318-89. representing perimeter joints of DMRFs with reinforced highstrength concrete. The influence on aseismic behavior of beam-column joints due tomonolithic slab, has been investigated.lab, has been investigated.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.2
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• pp.149-157
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• 2005

Statement of problem. Dental ceramics exhibit excellent esthetic property, compressive strength, chemical durability biocompatibility and translucency. However, it suffers from inherent brittle fractures. Various techniques and materials for intraoral porcelain repair has been suggested. Purpose. This study is to compare the tensile bond strength of four commonly used porcelain repair systems (Vivadent, Bisco, Ulttadent, Voco) and to insure the best system for the clinical application to the fractured porcelain. Materials and methods. A total of fifty specimens were fabricated. Specimens were stored in $37^{\circ}C$ distilled water for 7 days and thermocycling was performed(1000 cycles), and subjected to a tensile force parallel to the repair resin and porcelain interface by use of an Universal Testing Machine. Result. 1. Voco showed the highest tensile bond strength. In decreasing order, the tensile bond strength of the other materials was as follows : Ultradent, Bisco, Vivadent. 2. There was a statistically significant difference between the porcelain repair systems(Voco, Ultradent > Bisco, Yivadent) (p<0.05). 3. SEM examination of prepared porcelain surfaces revealed that the surface treated with Voco showed brittle fracture. However, Ultradent, Bisco and Vivadent showed ductile fracture. 4. All specimens treated with four porcelain repair systems showed adhesive failure between porcelain and composite resin.

• Hwankyungkyoyuk
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• v.19 no.1 s.29
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• pp.90-103
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• 2006

The purpose of this paper is to analyze media companies' editorial viewpoints regarding environmental issues. Not only do newspaper editorials provide a variety of environmental information, but also they make it possible for the public to form an opinion and to establish communication channels regarding environmental issues. With this in mind, this paper analyzes the changes in environmental reporting over the past two decades. The newspaper companies started writing more frequently about the environment from early 1980s. To show this, I analyzed environmental articles written in the six main news-paper companies: Chosun, Donga, Hangerae, Kyunghyang, Hankook, and Munwha from 1999 to 2004. For this study, the articles have been complied by using the Korean Integrated News Database System (KINDS). Also the data has been sorted according to year, subject, and ty the company of origin. The total number of the environmental articles posted on these six daily newspapers from 1999 to 2004 is 729 and these represent 2.59% of the total articles. Hankook-Ilbo was the company that handled the most of environmental articles followed by Hangerae, Munwha, Kyunghwang, Chosun, and Donga. The major topics of discussion were environmental development and water quality issues. The number of the environmental related articles increased in 1999 and 2000, but then decreased from 2001 to 2003. Again the number increased in 2004. Interestingly while the number of articles covering the environment increased from the 1980s and into the 1990s, the number of articles decreased from 1999 to 2004 as the post-IMF period seems to have suppressed interest in the ecological issues despite the economic growth that followed. With the change in media coverage people have begun to recognize environmental issues as having social impact. As a result the people have begun to take such issues more seriously and take more active role in effecting environmental policy. Thus it is important that the media presents it's stories in an object manner to insure that the public is properly informed.

• Korean Journal of Construction Engineering and Management
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• v.1 no.1 s.1
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• pp.45-52
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• 2000

In Korea, demand for the Social Overhead Capital(SOC) projects has tremendously increased since 1970's and is expected to keep growing to support national economic development as well as to enhance the quality of life. In these projects, project planning and feasibility study phase is one of the most critical phases because it determines the success of later phases. However, we have experienced trial and errors repeatedly such as cost overruns and schedule delays in many of the SOC projects. These problems can be prevented or at least expected in the earlier phase and it requires well-developed and standardized project planning process and systems before design, procurement, and construction phases begin. Therefore, the purpose of this research is to investigate current problems in this phase and provide framework for a model for the project planning management which can be used for the SOC projects to insure the whole project success.

• Korean Journal of Construction Engineering and Management
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• v.4 no.1 s.13
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• pp.122-130
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• 2003

Nowadays, as construction projects become bigger, the probability of construction accidents is higher than any other day. When construction accidents break out, we may suffer from the loss of life and property. For preventing these damages, there is lawed that some public constructions have to insure Contractor's all risks insurance policy (CAR), However, CAR is used to preventing the insured from the loss of construction accidents, it is debated that the premium rate of CAR is not fair to the insured (contractors) The objects of this thesis are as follows Firstly, the fairness of the premium rate of CAR is reviewed, and then the amount of risk of the insured evaluates and applies to the premium rate. Secondly, the development direction of components for evaluating the amount of risk of the insured is presented in the research. Lastly, how to use the team which assesses the risk of the insured and construction works is proposed for deciding reasonably the premium rate of CAR

• Journal of the Korean Institute of Gas
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• v.19 no.5
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• pp.29-35
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• 2015

Pipes, commonly used in energy and petrochemical facilities, have various types of defects induced by diverse factors and this is often issued in NDE society. Ultrasonic guided wave inspection method are normally adopted to insure the healthiness of industry pipes. Recently, ultrasonic guided wave inspection is shifted to adopt arrayed probes and system. And here we developed an array guided wave ultrasonic testing system can adapt arrayed probes and focusing methods. In this paper, an array guided wave ultrasonic testing system is presented including a transmitting focusing technique and flaw signal level enhancement.

• Fire Science and Engineering
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• v.23 no.6
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• pp.32-38
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• 2009

Owing to increase of the large-scaled, high-raised and complexed building construction, the escape design of the building became very important issue to insure the safety of occupant. Specially, it is demanded to have building escape regulation considering for inconvenient movers such as disables elders pregnant women. However, building regulations for inconvenient movers are divided into "Regulation of Escape and Fire-prevention of Building" and "Act on the Promotion and Guarantee of Access for the Disabled, the Aged and Pregnant Women to Facilities and Information". But, for the escape security of inconvenient movers, the connection of each regulation are necessary. So this study suggested the improvement direction of the building escape regulation considering inconvenient movers through the compared analysis on the "Regulation of Escape and Fire-prevention of Building" and "Act on the Promotion and Guarantee of Access for the Disabled, the Aged and Pregnant Women to Facilities and Information".

• Korean Journal of Metals and Materials
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• v.48 no.3
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• pp.194-202
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• 2010

Application of a stronger and more durable material for reactor pressure vessels (RPVs) might be an effective way to insure the integrity and increase the efficiency of nuclear power plants. A series of research projects to apply the SA508 Gr.4 steel in ASME code to RPVs are in progress because of its excellent strength and durability compared to commercial RPV steel (SA508 Gr.3 steel). In this study, the microstructural characteristics and mechanical properties of SA508 Gr.3 Mn-Mo-Ni low alloy steel and SA508 Gr.4N Ni-Mo-Cr low alloy steel were investigated. The differences in the stable phases between these two low alloy steels were evaluated by means of a thermodynamic calculation using ThermoCalc. They were then compared to microstructural features and correlated with mechanical properties. Mn-Mo-Ni low alloy steel shows the upper bainite structure that has coarse cementite in the lath boundaries. However, Ni-Mo-Cr low alloy steel shows the mixture of lower bainite and tempered martensite structure that homogeneously precipitates the small carbides such as $M_{23}C_6$ and $M_7C_3$ due to an increase of hardenability and Cr addition. In the mechanical properties, Ni-Mo-Cr low alloy steel has higher strength and toughness than Mn-Mo-Ni low alloy steel. Ni and Cr additions increase the strength by solid solution hardening. In addition, microstructural changes from upper bainite to tempered martensite improve the strength of the low alloy steel by grain refining effect, and the changes in the precipitation behavior by Cr addition improve the ductile-brittle transition behavior along with a toughening effect of Ni addition.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.4
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• pp.99-108
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• 2007

In the flat-plate slab design of the KCI and ACI building code, the punching shear strength of connections with shear reinforcement can increase one and half times to that of connections without shear reinforcement. And the ACI-ASCE committee 352 recommendations propose limiting the direct shear ratio $V_g$/$V_c$ on interior connections to 0.4 to insure adequate drift capacity. In this study, four interior column-slab connections were tested to look into the punching shear strength and the lateral displacement capacity of the flat-plate slab with and without shear reinforcement under cyclic lateral loading. Based on the test results, it is found that the provision about punching shear strength in the codes may appropriate for the gravity loading only whereas it is unconservative for the lateral loading and that the limit of ACI-ASCE committee 352 appears conservative.