• 한국농촌건축학회논문집
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• 제24권2호
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• pp.13-20
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• 2022

In this study, a general low-rise building was selected to compare the new shear wall reinforcement method, which is a general method among the existing reinforcement methods, and the reinforcement method using sinusoidal corrugated web reinforcement. And it was confirmed that the following effects can be expected. Sinusoidal corrugated web members can be carried out in a short period of time as it does not require the removal of the masonry filling wall, the reinforcement of reinforcing bars, and the curing period of the concrete. It is effective in preventing damage that may occur when masonry filling wall is overturned in the out-of-plane direction, and the burden of the foundation is also reduced, and thus the construction period and cost required for reinforcement can greatly be reduced. By adjusting the number of sinusoidal corrugated web member, details of joints, and reinforcement positions, the flow of load can be induced to have an advantageous effect on the building. It can be considered as the most suitable reinforcement plan in terms of life safety. Unlike the shear wall that fills between the columns, the sinusoidal corrugated web members, which has a width of 1.5m, can install openings between two columns depending on the purpose of use, and can be expected to have a great effect in terms of usability due to its free installation location. As mentioned above, the seismic reinforcement using a sinusoidal corrugated web members, can expect great effect compared to conventional reinforcement methods in terms of usability, economic feasibility, and stability.

• Advances in concrete construction
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• 제15권4호
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• pp.251-267
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• 2023

In this paper, an experimental investigation is carried out to assess the inherent self-compacting properties of geopolymer mortar and its impact on flexural strength of thin-walled ferro-geopolymer box beam. The inherent self-compacting properties of the optimal mix of normal geopolymer mortar was studied and compared with self-compacting cement mortar. To assess the flexural strength of box beams, a total of 3 box beams of size 1500 mm × 200 mm × 150 mm consisting of one ferro-cement box beam having a wall thickness of 40 mm utilizing self-compacting cement mortar and two ferro-geopolymer box beams with geopolymer mortar by varying the wall thickness between 40 mm and 50 mm were moulded. The ferro-cement box beam was cured in water and ferro-geopolymer box beams were cured in heat chamber at 75℃ - 80℃ for 24 hours. After curing, the specimens are subjected to flexural testing by applying load at one-third points. The result shows that the ultimate load carrying capacity of ferro-geopolymer and ferro-cement box beams are almost equal. In addition, the stiffness of the ferro-geoploymer box beam is reduced by 18.50% when compared to ferro-cement box beam. Simultaneously, the ductility index and energy absorption capacity are increased by 88.24% and 30.15%, respectively. It is also observed that the load carrying capacity and stiffness of ferro-geopolymer box beams decreases when the wall thickness is increased. At the same time, the ductility and energy absorption capacity increased by 17.50% and 8.25%, respectively. Moreover, all of the examined beams displayed a shear failure pattern.

• Advances in concrete construction
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• 제13권 2호
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• pp.123-132
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• 2022

This paper aims to adapt Multilinear regression (MLR) to predict the strength and toughness of SIFCON containing various pozzolanic materials. Slurry Infiltrated Fibrous Concrete (SIFCON) is one of the most common terms used in concrete manufacturing, known for its benefits such as high ductility, toughness and high ultimate strength. Assessment of compressive strength (CS.), flexural strength (F.S.), splitting tensile strength (STS), dynamic elasticity modulus (DME) and impact energy (I.E.) using the experimental approach is too costly. It is time-consuming, and a slight error can lead to a repeat of the test and, to solve this, alternative methods are used to predict the strength and toughness properties of SIFCON. In the present study, the experimentally investigated SIFCON data about various mix proportions are used to predict the strength and toughness properties using regression analysis-multilinear regression (MLR) models. The input parameters used in regression models are cement, fibre, fly ash, Metakaolin, fine aggregate, blast furnace slag, bottom ash, water-cement ratio, and the strength and toughness properties of SIFCON at 28 days is the output parameter. The models are developed and validated using data obtained from the experimental investigation. The investigations were done on 36 SIFCON mixes, and specimens were cast and tested after 28 days of curing. The MLR model yields correlation between predicted and actual values of the compressive strength (C.S.), flexural strength, splitting tensile strength, dynamic modulus of elasticity and impact energy. R-squared values for the relationship between observed and predicted compressive strength are 0.9548, flexural strength 0.9058, split tensile strength 0.9047, dynamic modulus of elasticity 0.8611 for impact energy 0.8366. This examination shows that the MLR model can predict the strength and toughness properties of SIFCON.

• Computers and Concrete
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• 제33권6호
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• pp.707-724
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• 2024

This paper proposes a study of cement replacement with rice husk ash (RHA) and eggshell ash (ESA) for enhanced mechanical properties of geopolymer (GP) concrete with and without admixture. The main objective is to investigate the mechanical properties of GP with various replacement levels of Pozzolana Portland cement by RHA and ESA. The GP resistance to durability is examined and impact of ash materials on concrete's durability performance is determined. The environmental benefits of using agricultural waste materials in GP manufacturing minimize cement usage and CO2 emissions. The goal is to assess value of RHA-ESA of building material, paving stones for structures to lessen environmental impact. The novelty lies in use of ESA and RHA as partial replacements for cement and investigation of admixtures to enhance concrete properties, and reduce environmental impact. The research contributes by introducing a novel approach to reducing cement consumption by using ESA and RHA to address environmental concerns. It also explores the potential benefits of admixtures improving concrete performance and reducing environmental pollution. A study is carried with and without impacts of admixture to find compressive strength of GP cubes. The cement has been replaced by RHA and ESA in the range of (2.5%+7.5%, 5%+5%, 7.5%+2.5) by weight of cement for M20 mix. The compressive strength (CS) and split tensile strength (STS) at 7days, 14 days and 28 days is obtained as 21 N/mm2 at 7.5%RHA+2.5%ESA and 2.3 at 7.5%RHA+2.5%ESA, 24 N/mm2 at 7.5%RHA+2.5%ESA and 2.3 at 7.5%RHA+2.5%ESA, 28 N/mm2 at 7.5%RHA+2.5%ESA and 2.8 at 7.5%ESA respectively with normal curing condition.

• Geomechanics and Engineering
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• 제36권6호
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• pp.589-599
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• 2024

Dispersion occurs when clay soil disperses under specific conditions and is rapidly washed away. While there are numerous methods for rectifying it, they are neither cost nor time-effective. The current study used metakaolin and zeolite to improve heavily dispersive clay soil either separately or in combination at 0%, 2%, 4%, 6%, and 8% of the soil weight. After 7 days of curing, the samples were tested to determine the extent of change in the dispersion potential, as well as the improvement of the geotechnical properties of the soil. The results indicated that the addition of 2% zeolite with 6% to 8% metakaolin decreased the dispersion potential considerably. Double hydrometry test findings revealed that the dispersion potential decreased by almost 70% and entered the non-dispersive group; the crumb test also revealed this. Atterberg limits testing indicated a decrease in the plasticity index which reduced the flexibility of the samples. The greatest decrease in PI (67.5%) was achieved with the addition of 8% zeolite plus 8% metakaolin to the soil. The results of density tests revealed that a decrease in the optimal moisture content increased the maximum dry density of soil. This increase in density was a response to the high reactivity of metakaolin with calcium hydroxide and the formation of calcium hydroxide hydrate gel. This eventually caused an increase in the unconfined compressive strength, the greatest increase in strength of about 1.8-fold was observed with a combination of 2% zeolite and 6% metakaolin compared to the unmodified sample.

• 대한방사선치료학회지
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• 제17권2호
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• pp.133-140
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• 2005

목 적 : 3차원치료계획 (3D plan)과 대향2문조사(POP plan)의 선량 계획시 치료표적 (Planning Target Volume, PTV)와 정상조직(Organ at Risk, OAR)에 실제 흡수되는 선량을 반도체검출기를 이용하여 실시간선량측정(Real- time dosimetry)을 시행함으로써 치료계획의 타당성을 확인하고자 한다. 대상 및 방법 : 실제 치료할 환자의 구강안을 채워줄 Aquaplaste를 Simulation과정에서 제작하며 측정하고자 하는 부위에 Aquaplaste를 성형하여 반도체 검출기가 자리할 공간을 확보한다. 치료시 반도체검출기를 측정부위에 위치시키고 치료가 진행중 각 Port에 해당하는 Electrometer의 지시치를 얻는다. 얻은 지시치에 선량변환계수(Diode Calibration Factor, DCF)를 이용하여 실제 선량으로 환원하여 Exp. Dose와 실제 Dose를 비교하며 오차를 구한다. 실험의 수를 증가시켜 보다 정확한 결과를 얻기 위하여 Alderson Rando phantom(Huestis, USA)을 이용하여 같은 실험을 반복한다. 결 과 : 대향2문조사를 한 A환자의 경우 Exp. value와 측정선량의 비(exp.D/eff.D)가 197.5/199로 -1.2%, 3차원치료계획을 한 B환자는 exp.D/eff.D가 199.9/198.7로 +0.6%, C환자의 경우 exp.D/eff.D가 196/200으로 -1.5%가 차이 남을 알 수 있었다. 또 Target dose 외에 방어하고자 하는 부위의 측정도 병행한 C환자의 결과치는 96/200으로 47%의 선량이 측정되어 방어의 목적을 달성했음을 알 수 있었다. Phantom을 이용한 측정에서는 A환자와 같이 (a) point(target), (b) point(protect)로 나뉘어 측정하여 다음의 결과치를 얻었다. Phantom 1 (a): 190.6/198.4=-3.9%, (b): 119.6/124.2=-3.7%, Phantom 2 (a): 185.4/191.3=-3%, (b): 109.6/113.8=-3.7%의 결과치를 얻어 목적한 선량에 ${\pm}5%$이내로 만족함을 알 수 있었다. 결 론 : 반도체검출기를 이용한 치료전 선량 측정의 유용성을 알아본 이번 실험은 Target dose 뿐만 아니라 방어하고자 하는 영역 또한 알아봄으로써 치료의 타당성을 확인하는데 매우 유용했고 단순선량계산에 의한 확인되지 않는 Target dose를 확인하는 데에도 큰 이점이 있다고 생각된다. 치료 전 L-gram과 같이 이런 측정은 매우 효과적으로 치료방법의 타당성과 이후의 치료계획에도 많은 이득을 가져다 줄 것이라고 생각된다.

• 대한치과교정학회지
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• 제26권2호
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• pp.233-244
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• 1996

성인 환자의 증가와 심미적인 장치에 대한 요구가 증가하면서 도재나 레진 브라켓의 사용이 증가되고 있다. 이러한 브라켓에서의 광중합 접착제의 사용은 짧은 광조사 시간에서도 광중합 접착제의 많은 장점을 얻을 수 있다. 이에 본 연구에서는 심미적으로 우수한 수 종의 도재 및 레진 브라켓을 수 종의 광중합 접착제로 접착시켜 전단 접착 강도와 접착 파절 양상을 관찰하였다. 교정 치료를 위해 발거한 140개의 소구치를 협측면이 노출되도록 자가중합 레진으로 매몰하고 소구치 협측면에 Plastlc bracket, Transcend 6000, Signature 및 Starfire TMB 브라켓을 Orthobond, Light Bond 및 Transbond로 제조자 지시에 따라 접착시켜 열변환기 로 1800회 온도 변화를 준 후 전단 접착 강도를 만능시험기로 측정하고 접착 파절 양상을 입체현미경으로 관찰하였고 10초와 20초의 광조사 시간과 두가지 광원에 대해 전단 접착 강도를 비교하여 다음의 결과를 얻었다. 1. 동일한 브라켓을 Orthobond, Light Bond와 Transbond로 접착시켰을 때 이들간의 전단 접착 강도는 Plastic bracket을 제외하고는 통계학적 유의차가 없었다(p<0.05). 2. 동일한 접착제로 Plastic bracket, Transcend 6000, Signature, Starfire TMB를 접착시켰을 때 이들간의 전단 접착강도는 통계학적 유의차를 보였다(p<0.05). Starfire TMB에서 가장 큰 전단 접착강도를 보였고 이는 Transcend 6000과 통계학적 유의차가 없었으나 Singnature와는 통계학적 유의차를 보였다(p<0.05). 3. 접착 파절은 전체 군에서 잔류 접착제가 반 이상 또는 모두 치아면에 남은 경우가 $72.1\%$로 대개 브라켓과 접착제 사이에서 파절이 일어났다. 4. 접착제 중합을 위한 광조사 시간은 10초와 20초에서 전단 접착 강도에 통계학적 유의차를 보이지 않았으며 $400mW/cm^2$ 이상의 광도에서는 서로 다른 광원을 사용해도 전단 접착 강도에 통계학적 유의차를 나타내지 않았다(p<0.05). 이상의 결과로 보아 도재 브라켓의 전단 접착강도는 브라켓 조성과 브라켓 접착면의 유지형태 차이에 의해 영향을 받고 광중합 접착제 종류에 따른 접착 강도의 차이는 나타나지 않았으며 임상에서 브라켓이나 접착제 선택시 이를 고려해야 할 것으로 사료된다.

• 동의생리병리학회지
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• 제21권1호
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• pp.18-27
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• 2007

${\ll}$Gup Yu Bang${\gg}$ is the first korean book that specialized in pediatrics. It was written by Jo Jeong-jun in 1869 and contains 87 medical records. Medical records is one of the best way to develop one’s abilities of curing a disease without clinical practice and understanding medical condition of the time. These days we are fully aware of the importance of medical records, but there is no sufficient paper or study on medical records. On this study, we investigate 87 medical record of ${\ll}$Gup Yu Bang${\gg}$ by statistical methods. It was analyzed on the base of items such as age, sex, disease, method of medical treatment, treating prescription, modified medicinal substance, progress of disease. ${\ll}$Gup Yu Bang${\gg}$ contain 87 medical records and among of them, 84 records were Jo Jeong-jun own writings of clinical case. Systemic division of disease showed the highest in digestive disease and most frequent case was symptom of vomiting and diarrhea. The distribution of age was showed the highest in the age group under 5 years and the number of male case was more than female case. It showed that he considered observation of the patient's expression in diagnosis methods and have used 87 kinds of treating prescription and the external treatment, acupuncture, moxa. It showed that he quoted a lot of treating prescription from ${\ll}$Dong eui bo gam${\gg}$, ${\ll}$Yi-Hak-Yip-Mun${\gg}$ and ${\ll}$Xiao Er Yao Zheang Zhi Jue${\gg}$. The further study on medical records in traditional medical literatures, would reveal the developmental progress of Korean pediatrics and inform more actual proof on medical condition of the time.

• 한국치위생학회지
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• 제8권2호
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• pp.53-66
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• 2008

There was to purpose of this study improves analyzing cause that prosthesis brings bite engaging that is inaccurate in patient's mouth, when supposed that all conducts that do in operatory and dental laboratory are perfect. Impression did check bite by alginate impression material and polymerization style silicon impression material that use usually in presence at a sickbed Irreversibility, hydrocolloid, alginate impression material washed in flowing water and poured anhydrite after wait about 8 minutes so that region that charge interest after impression check bite may become undoing. And hydrophile property addition polymerization style impression material poured anhydrite after blow 30 considering impression material dwell time and H2 gas occurrence time (5~15 minute) after have washed in flowing water. I got each 7 models, result that manufactures total 28 and measures by third dimension measuring instrument (Meteo, Korea) following sequence curing in tray holder and floor 1, By Alginate impression when is hardened in tray holder and when is hardened in the floor after do check bite, SPH 4, SPH5 all as there is synonymy appeared(P<0.05). By in case do not use average 0.1741 in case use tray holder in 0.0447 SPH5s in case do not use average 0.2838 pastas in case use tray holder in SPH4 0.0309, When did not use both SPH4 and SPH5 tray holder, when used tray holder, 1 appeared more greatly. 2. By amity sex addition polymerization style silicon impression when is hardened in tray holder after do check bite and when is hardened in the floor SPH 4, a11 of the SPH5s very big synonymy be(P>0.05). And in case use tray holder in 0.000657 pasta SPH5s in case do not use average 0.000129 pastas in case use tray holder in SPH4 average 0.000114 pastas, by in case do not use 0.000757, I appeared more greatly when used tray when did not use both SPH4 and SPH5 tray holder, but 1 appeared is not level to keep in mind(Table 8~9). 3 SPH4 was looked very big mindfulness in model that manufacture doing impression check bite by Alginate and model that do impression check bite by amity sex accessory penalty silicon without using tray holder(P< 0.001). I use tray holder and SPH4 did not appear synonymy in model that manufacture doing impression check bite by Alginate and model that do impression check bite by amity sex accessory penalty silicon(P>0.05). Study finding of above when see synthesis Alginate certainly tray holder use must and I could know that hardening method does not exert big influence on volume stability if remove impression sieve of excess because amity sex accessory penalty silicon passes over tray, Also, Alginate impression material previewed can get heading a conspiracy style that volume stability of accessory penalty silicon impression material degree is if use tray holder.

• Geomechanics and Engineering
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• 제21권5호
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• pp.433-445
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• 2020

The weakening and softening behavior of soft clay subjected to cyclic loading due to the build-up of excess pore water pressure is well-known. During the design stage of the foundation of highways and coastal high-rise buildings, it is important to study the mechanical behavior of marine soils under cyclic loading as they undergo greater settlement during cyclic loading than under static loading. Therefore, this research evaluates the cyclic stress-strain and shear strength of untreated and treated marine clay under the effects of wind, earthquake, and traffic loadings. A series of laboratory stress-controlled cyclic triaxial tests have been conducted on both untreated and treated marine clay using different effective confining pressures and a frequency of 0.5 and 1.0 Hz. In addition, treated samples were cured for 28 and 90 days and tested under a frequency of 2.0 Hz. The results revealed significant differences in the performance of treated marine clay samples than that of untreated samples under cyclic loading. The treated marine clay samples were able to stand up to 2000 loading cycles before failure, while untreated marine clay samples could not stand few loading cycles. The untreated marine clay displayed a higher permanent axial strain rate under cyclic loading than the treated clay due to the existence of new cementing compounds after the treatment with recycled tiles and low amount (2%) of cement. The effect of the effective confining pressure was found to be significant on untreated marine clay while its effect was not crucial for the treated samples cured for 90 days. Treated samples cured for 90 days performed better under cyclic loading than the ones cured for 28 days and this is due to the higher amount of cementitious compounds formed with time. The highest deformation was found at 0.5 Hz, which cannot be considered as a critical frequency since smaller frequencies were not used. Therefore, it is recommended to consider testing the treated marine clay using smaller frequencies than 0.5 Hz.