• The Journal of Korean Academy of Prosthodontics
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• v.37 no.2
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• pp.143-166
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• 1999

The success of porcelain laminate veneer depends on the bond strength between tooth structure and ceramic restoration and the design of tooth preparation. In particular, incisal coverage and incisal finish line are the two most important factors in long-term fracture resistance. Although the majority of clinicians are practicing incisal coverage and there are various opinions on the geo-metrical ratio between the clinical crown length of the remaining tooth structure and the length of incisal extension in porcelain laminate veneer and the optimal incisal finish lines. scientific evidence still loaves much to be desired. The purpose of this study was to determine the effects of the amounts of incisal coverage and the types of incisal finish line on the stress distribution in maxillary anterior porcelain laminate veneers under two different loading conditions. Three-dimensional finite element models of a maxillary anterior porcelain veneer with differ-ent amounts of incisal coverage ; 0, 1, 2, and 3mm and different incisal finish lines feathered edge, incisal bevel, reverse bevel and lingual chamfer with various amounts of lingual extension were developed. 300N force was applied at the point 0.5mm cervical of the linguoincisal edge in two loading conditions ; A) 125 degrees, B) 132 degrees. Tensile and compressive stress in ceramic and shear stress in the resin cement layer were analyzed using three-dimensional finite element method. The results were as follows : 1. The types of incisal finish line had more influence on the stress distribution in porcelain laminate veneer than the amounts of incisal coverage. 2. In case of no incisal coverage, incisal beveled laminate exhibited more evenly distributed tensile stress than feathered edged laminate. And in case of incisal coverage, reverse beveled laminate and lingual chamfered laminate with 1mm lingual extension exhibited more evenly distributed tensile stress than lingual chamfered laminates with 2mm and 3mm lingual extension. 3. As long as the lingual chamfer goes, less tensile stress was found at the incisal edge, while much more tensile stress was found at the lingual margin area in proportion to the length of lingual extension. 4. Under 125 degree load, tensile stress in porcelain laminate veneer had increased compared with that under 132 degree load and the difference exhibited by the change of the amount of tooth support was larger. 5. The types of incisal finish line and the distance from the incisal finish line to the loading point had more influence on the shear stress distribution in the resin cement layer than the amounts of incisal coverage. In contrast loading condition had little influence.

• Journal of the Korean Solar Energy Society
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• v.40 no.4
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• pp.13-22
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• 2020

As the supply of photovoltaic (PV) increases worldwide, the cumulative installations in 2018 were 7.9 and 560 GW in Korea and the world, respectively. Typically, when the ground on commercial PV modules is installed, the area is limited; hence, new designs of PV modules are required to install additional PVs. Among the new design of PV modules, lightweight PV modules can be utilized in PV systems, such as buildings, farmlands, and floating PV. Concerning the investigation of lightweight PV modules, several studies on materials for replacing low-iron tempered glass, which comprises approximately 65% of the PV module weight, have been conducted. However, materials that are used as substitutes for glass should possess similar lightweight properties and reliability as glass. In this study, experimental tests were performed to evaluate the applicability of ethylene tetrafluoroethylene (ETFE) film with excellent resistance to water and aging as a front material of PV modules. The transmittance and ultraviolet properties of the ETFE film were determined and compared with those of glass. A 1-cell module and laboratory-scale 24-cell module were manufactured using the ETFE film and glass, and the electrical output was measured and analyzed. Furthermore, damp heat and thermal cycle tests were conducted to evaluate the reliability of the ETFE film module. Based on the experimental results, the electrical output and reliability of the ETFE film module were similar to those of the glass module, and the ETFE film could be used as the front material of PV modules.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.207-216
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• 2003

Drilled deep foundations of large diameter are often used for foundations of transmission towers. As tower structures become larger in modern society, there is a need of more efficient and economical design of large-diameter drilled deep foundations. Reinforced drilled deep foundations are popular in Japan for the foundation of tower structures. Stiffeners attached to the shaft of the foundation are used to increase the shaft resistance. This study aims at analyzing the effect of reinforcement with large-diameter drilled deep foundations based on numerical analysis of the representative soil and rock conditions in Korea. The numerical analyses are conducted to analyze the reinforcement effect of various stiffener conditions of number, inclination, location and length. Regarding to number of stiffeners, the effect of reinforcement for weathered and soft rocks increases proportionally as the number of stiffeners increases. For weathered soil, however, the effect of reinforcement increases at a lower rate. The effect of stiffener location is nearly negligible for axially loading cases, while it is significant for laterally loading cases. For the laterally loading cases, upper locations of stiffener give greater reinforcement effect than that of lower location. For stiffener inclinations of axial loading cases, a stiffener inclination equal to 60$^{\circ}$ gives the greatest reinforcement effect.

• Journal of the Korean Geotechnical Society
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• v.32 no.9
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• pp.17-27
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• 2016

Parial drainage characteristics of clayey silt with low plasticity from the west coast (Incheon and Hwaseong) was analyzed using CPTU based existing correlation equations and compulsory replacement method. Generally, the estimated $OCRs={\kappa}{\cdot}((q_t-{\sigma}_{vo})/{\sigma}^{\prime}_{vo})$ using Powell and Quartman(1988) were higher than those obtained by the oeodometer tests. These trends were noticeable for the layers containing a lot of silty and sand soils. The assessment of partial drainage conditions was performed through Schnaid et al. (2004)'s equation; it is based on plotting the normalized cone resistance, $Q_t$ versus the pore pressure parameter, $B_q$ in combination with the strength incremental ratio, $s_u/{\sigma}^{\prime}_{vo}$ to the CPTU data. It is evident that more than half of the data fall in the range where $B_q$ < 0.3, corresponding to the domain in which the partial drainage prevails when testing normally consolidated soils at a standard rate of penetration (2 cm/s). To estimate the replacement depth of clayey silt with low plasticity, back analysis was carried out to evaluate the internal friction angle based on where the design depths are equal to the checked depths using bearing capacity equation. The internal friction angels obtained from the back analysis tended to increase as the plasticity index decreases, which is ranged approximately from ${\varphi}^{\prime}=2^{\circ}$ to ${\varphi}^{\prime}=7^{\circ}$.

• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.587-594
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• 2005

The purpose of seismic design is to ensure the serviceability of buildings against earthquake, which might be occurred during the service life of buildings, and to minimize the loss of life by preventing their failure under strong earthquake. The lack resistance of walls resulting from a tendency toward high-rise apartment buildings with shear walls and use of piloti would lead to a concentration of inelastic behaviors in their weak story. In this study, the seismic performance of reinforced concrete shear wall buildings haying piloti was analyzed by using the evaluation techniques which was proposed by FEMA 273 and ATC-40. The results from comparison with these two techniques are summarized as follows.; The results of elastic analysis method for seismic performance evaluation show that the effect of piloti and building height decrease performance index. In case of shear wall building, the state of insufficient shear stress governs their overall performance and it becomes evident in the case of the buildings with more than 25 stories. For the buildings of piloti, the change of mass, weak story, as well as insufficient shear stress, decrease the performance index rapidly compared with the performance index of the buildings without piloti. The results, obtained from the nonlinear static analysis using capacity spectrum method, indicate that the performance Point increases for the structure having Piloti and high story. Also, deformation limits of buildings satisfy the allowable criteria at the life safety level, but the immediate occupancy level is exceeded in buildings which have more than 25 stories.

• Journal of the Korea Concrete Institute
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• v.26 no.6
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• pp.679-686
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• 2014

In this research, the mix proportion of the antiwashout underwater concrete with the mineral admixture was evaluated. It can reduce the amount used of the antiwashout admixture (hereinafter referred to as "AWA") and satisfy the properties of concrete. In addition, the review for the difference of the test and practical affairs were conducted. Optimized unit quantity of water of antiwashout underwater concrete and the amount used of AWA was revealed by $190kg/m^3$, 0.9%/W, respectively. In particularly, the mix design is reduced by 5% than the W/B of target strength even though the W and AWA reduced. Therefore, it will have the economical feasibility and qualities including the material separation, resistance characteristic and compressive strength, and etc. The stable value was shown in 1 point of minute passed in the measurement of the turbidity amounts using the turbidimeter after the checker insertion. However, it needs to be reviewed for the interrelationship between turbidity measuring machine and KCI-AD102 standard method. There were no significant differences of compressive strength of specimens in the water depending on the production methods.

• Journal of Korean Medicine Rehabilitation
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• v.20 no.2
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• pp.63-77
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• 2010

Objectives : It is known that abdominal obesity increases the possibility of cardiovascular diseases, early death, and metabolic syndrome including dyslipidemia and insulin resistance. Clinical trials have been under way to verify the effectiveness of treatment for abdominal obesity. The objective of this study is to set criteria about how effective oriental medicine and acupuncture are in abdominal obesity. Methods : I manually search "www.clinicaltrial.gov", 4 Korean medical databases and 4 Korean medical journals of abdominal obesity. Search terms used were "abdominal obesity" or "visceral obesity". In order to see detail review, searching was performed from 01, 01, 2005 to 11, 31, 2009. And I classified all the searched studies into design, intervention, purpose, end point, diseases, condition and etc. Results : 1. I could search total 67 trials in "www.clinicaltrial.gov". I found 9, 10, 13, 8, 6 clinical trial from 2005 to 2009 every year. 2. Test on both gender and adult or adult and senior have been most frequent. 3. Randomization clinical trial is 51 cases that occupied 96.2%. 38 cases use control group. 4. Body mass index(BMI) and waist circunference(WC) are major criteria of abdominal obesity clincal trial. WC, BMI, abdominal fat mass, body weight are measured at end point of abdominal obesity clincal trial. 5. I could search total 86 cases in domestic study. I found 15, 23, 23, 20, 5 cases from 2005 to 2009 every year. 6. Test on female and adult have been most frequent in domestic study. 7. Randomization clincal trial is only 2 cases that occupied 2.3%. 62 cases use control group in domestic study. 8. BMI, body fat percent, WC, visceral-subcutaneous fat ratio(VSR), waist-hip ratio(WHR) are criteria of abdominal obesity clincal trial in domestic study. WC, BMI, abdominal fat mass, body weight are measured at end point of abdominal obesity clincal trial in domestic study. Conclusions : To improve abdominal obesity study in traditional korean medicine, it is need to activate clinical trial, meta analysis, develope of clinical practice guidelines, co-works with conventional medicine and etc.

• Journal of Biosystems Engineering
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• v.25 no.3
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• pp.213-220
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• 2000

Grafting of fruit-bearing vegetables has been widely used to increase the resistance to soil-borne diseases, to increase the tolerance to low temperature or to soil salinity, to increase the plant vigor, and to extend the duration of economic harvest time. After grafting, it is important to control the environment around grafted seedlings for the robust joining of a scion and rootstock. Usually the shading materials and plastic films are used to keep the high relative humidity and low light intensity in greenhouse or tunnel. It is quite difficult to optimally control the environment for healing and acclimation of grafted seedlings under natural light. So the farmers or growers rely on their experience for the production of grafted seedling with high quality. If artificial light is used as a lighting source for graft-taking of grafted seedlings, the light intensity and photoperiod can be easily controlled. The purpose of this study was to develop a prototype system for the graft-taking enhancement of grafted seedlings using artificial lighting and to investigate the effect of air current speed on the distribution of air temperature and relative humidity in a graft-taking enhancement system. A prototype graft-taking system was consisted by polyurethane panels, air-conditioning unit, system controller and lighting unit. Three band fluorescent lamps (FL20SEX-D/18, Kumho Electric, Inc.) were used as a lighting source. Anemometer (Climomaster 6521, KANOMAX), T-type thermocouples and humidity sensors (CHS-UPS, TDK) were used to measure the air current speed, air temperature and relative humidity in a graft-taking system. In this system, air flow acted as a driving force for the diffusion of heat and water vapor. Air current speed, air temperature and relative humidity controlled by a programmable logic controller (UP750, Yokogawa Electric Co) and an inverter (MOSCON-G3, SAMSUNG) had an even distribution. Distribution of air temperature and relative humidity in a graft-taking enhancement system was fairly affected by air current speed. Air current speed higher than 0.1m/s was required to obtain the even distribution of environmental factors in this system. At low air current speed of 0.1m/s, the evapotranspiration rate of grafted seedlings would be suppressed and thus graft-taking would be enhanced. This system could be used to investigate the effects of air temperature, relative humidity, air current speed and light intensity on the evaportranspiration rate of grafted seedlings.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.1
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• pp.81-88
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• 2020

Flight data recorder is a equipment that records data required for investigation of aircraft accidents and should be developed in compliance with the ED-112A standard. Unlike general data storage device, flight data recorder must be able to recover data after an aircraft accident, requiring a housing and a memory board to protect data in extreme environments. To attain this performance, we designed a housing that can withstand the test by analyzing the physical environment of the impact, shear/tensile, penetration resistance and static crush test of the crash survival test and minimized the size and weight compared to the existing one in consideration of the installation of the aircraft in this paper. Insulation material and thermal block material were applied to endure high and low temperature fire so that the internal temperature does not rise above 150℃ even in 260℃, 10 hour environment. In addition, the memory board is designed to minimize the size and we devise a hoping programming method to prevent continuous data loss of more than 16 seconds. Through this, Crash protected memory module that satisfies ED-112A was completed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.1
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• pp.64-71
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• 2020

eFuse OTP memory IP is required to trim the analog circuit of the gate driving chip of the power semiconductor device. Conventional NMOS diode-type eFuse OTP memory cells have a small cell size, but require one more deep N-well (DNW) mask. In this paper, we propose a small PMOS-diode type eFuse OTP memory cell without the need for additional processing in the CMOS process. The proposed PMOS-diode type eFuse OTP memory cell is composed of a PMOS transistor formed in the N-WELL and an eFuse link, which is a memory element and uses a pn junction diode parasitic in the PMOS transistor. A core driving circuit for driving the array of PMOS diode-type eFuse memory cells is proposed, and the SPICE simulation results show that the proposed core circuit can be used to sense post-program resistance of 61㏀. The layout sizes of PMOS-diode type eFuse OTP memory cell and 512b eFuse OTP memory IP designed using 0.13㎛ BCD process are 3.475㎛ × 4.21㎛ (= 14.62975㎛2) and 119.315㎛ × 341.95㎛ (= 0.0408mm2), respectively. After testing at the wafer level, it was confirmed that it was normally programmed.