• 한국세라믹학회지
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• 제42권1호
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• pp.37-42
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• 2005

유리연마슬러지와 graphite를 발포제로 사용하여 경량골재를 제조하였으며, 경량골재 내부기공과 물성과의 상관성을 도출하였다. 이때 graphite 함량을 각각 달리하여 성구를 제조하였으며, $700^{circ}C$ 및 $800^{circ}C$에서 20분 동안 소성하였다. 소성 전후 골제의 부피 변화를 검토한 결과, 발포제의 첨가량보다는 소성 온도가 즘 더 큰 영향을 미침을 확인하였다 기공의 크기 및 면적은 발포제 첨가량과 소성 온도 상승에 따라 증가하는 특징을 나타내었으나, 발포제 첨가량 $1\%$ 이상에서는 큰 폭의 증가를 동반하지 않았다. 흡수율/열전도율과 기공과의 상관성은 매우 높아, 각각의 상관관계계수는 $0.8\pm$ 이상을 나타내었다.

• 한국구조물진단유지관리공학회 논문집
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• 제26권4호
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• pp.40-47
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• 2022

이 연구의 목적은 철근콘크리트 벽체의 내력, 변형 및 균열진전에 대한 개구부 모서리의 사인장 균열 제어를 위한 다양한 보강방법들이 효율성을 평가하는 것이다. 개구부 모서리의 사인장 균열제어 보강방법으로서 이 연구에서 제안한 균열제어 띠, 기존의 경사보강근 배근방법, 그리고 응력분산곡면판을 선택하였다. 균열제어 띠에서는 균열치유 기능성이 부여된 것도 함께 고려하였다. 개구부 주위의 체적변화 및 균열 폭 진전을 평가하기 위하여 개구부 모서리에서 사인장 균열 유도를 위한 축소 벽체 실험을 수행하였다. 실험결과 균열제어 띠는 경사보강근 및 응력분산곡면판에 비해 개구부 주위의 체적변화 감소 및 개구부 모서리 균열 폭 제어에 효율적이었다. 균열 치유 기능이 포함된 균열제어 띠는 사전 실험에서 발생한 균열들을 치유하면서 축소 벽체의 내력 향상 및 균열 폭 감소에 가장 좋은 성능을 보였다.

• 한국식품조리과학회지
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• 제22권4호통권94호
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• pp.477-487
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• 2006

The quality characteristics of dough and French breads containing dietary fibers, which were resistant starches (RS3 and RS4 types) and commercial non-starch polysaccharides (cellulose, pectin and chitosan), were investigated. The pH of the dough containing all dietary fiber except pectin was greater than that of control and was increased with increasing addition level. There was no correlation between pH and the expansion ratio of dough. As the level of added dietary fibers became high, the bread baking loss decreased, and the order of specific bread volume was 5% cellulose < 5% pectin < control bread, with no significant difference in specific volume. When a high level of dietary fibers was added to wheat flour, a complex phase appeared due to the formation between the network structure of additives and wheat gluten, and starch granules were heavily masted by the increased development of gluten-network matrix after the first fermentation like a wide spread net. Comparing the colorimetric changes of breads with the same added ratio (10%) of dietary fibers, the cellulose and RS4 addition breads had lower levels and the pectin-added bread had the highest value in the redness, while the chitosan-added bread had the highest value in the yellowness. Breads with a high level of dietary fibers showed increased hardness, gumminess, and brittleness and decreased springiness and cohesiveness. By sensory data, breads with 5% NSP and 10% RS addition showed high overall acceptability, with higher sensory RS score, compared to NSP addition. In conclusion, it was suggested that bread with lower than 10% RS or 5% NSP addition based on the amount of wheat flour, was acceptable with no considerable change in preference/overall quality and processing in bread-making.

• 한국지반환경공학회 논문집
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• 제9권2호
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• pp.61-65
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• 2008

본 연구에서는 PGSN(Pressurized Grouting Soil Nailing) 시스템이라는 가압 그라우팅 쏘일네일링 공법을 고안하였으며, 본 공법의 보강제의 길이변화 및 보강재의 변화 등의 설계인자에 따른 거동변화를 파악해 보기 위해 변위제어방식의 현장인발시험을 수행하였다. 본 연구에서 수행한 9차례의 현장인발시험에서 그라우트 주입비의 변화를 살펴 보기위해 계측을 수행하였으며, 단기거동특성을 평가하기 위해 일반 쏘일네일링 시스템과 비교해 보았다. 가압 그라우트 쏘일네일링 공법의 인발거동 특성을 통해, 중요한 설계인자인 주입압 및 그라우트 주입비 등의 영향을 살펴보았다. 시험 결과 가압효과에 따른 인발변형 특성은 중력식 그라우팅 쏘일네일에 비해 가압 그라우팅 쏘일네일의 경우 유발되는 변위량이 30~36% 정도 감소하였고, 보강재 변화에 따른 인발 특성을 살펴보면 이형철근에 비해 강관의 경우 유발되는 변위량이 31~32% 정도 감소하는 것으로 나타났다.

• 대한두개안면성형외과학회지
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• 제22권2호
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• pp.85-92
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• 2021

Background: Patients with secondary deformities associated with unilateral cleft lip and nose might also suffer from nostril stenosis due to a lack of tissue volume in the nostril on the cleft side. Here, we used full-thickness skin grafts (FTSGs) to reduce nostril stenosis and various methods for skin volume augmentation. We compared the changes in the symmetry of both nostrils before and after surgery. Methods: From February 2016 to January 2020, 34 patients underwent secondary cheiloplasty and open rhinoplasty for secondary deformities of the unilateral cleft lip and nose with nostril stenosis. FTSG was used on the nostril floor, nasal columella, and alar inner lining. The measured nasal profile included the nostril surface, nostril circumference, width of the nostril floor, and distance from the alar-facial groove to the nasal tip. The "overlap area," which was defined as the largest overlapping area when the image of the cleft nostril was flipped to the left and right and overlaid on the image of the normal side nostril, was also calculated. The degree of symmetry was evaluated by dividing the value of the cleft side by that of the normal side of each measured profile and expressed as "ratios." Results: The results of all profile ratios, except for the nostril floor width, became significantly close to 1, which represents full symmetry. The overlap area ratio improved from 62.7% to 77.3%, meaning that the length and width of the nostril as well as the overall shape became similar (p< 0.05). Conclusion: When performing cleft rhinoplasty with nostril stenosis, FTSG is useful to achieve symmetry in the nostril size and shape. Skin grafting is simpler to perform than the other types of local flap, and the results are generally satisfactory.

• 한국염색가공학회지
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• 제34권3호
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• pp.207-216
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• 2022

Hydrogels have gained considerable attention in various fields due to their easily transformative ability by different stimulation. In addition, metal-based conductive additives can enable the hydrogels to be conductive with dimension change. Although the development of the additives offered enhanced electrical properties to the hydrogels, correspondingly enhanced mechanical properties may limit the volume and electrical properties switching after stimulation. Here we prepared poly(N-isopropylacrylamide) (PNIPAM) thermo-responsive hydrogel that has a 32℃ of low critical solution temperature and added liquid metal particles (LMPs) as conductive additives, possessing soft and stretchable benefits. The LMPs enabled PNIPAM (PNIPAM/LMPs) hydrogels to be constricted over 32℃ with a high volume switching ratio of 15.2 when deswelled. Once the LMPs are spontaneously oxidized in hydrogel culture, the LMPs can release gallium ions into the hydrogel nature. The released gallium ions and oxidized LMPs enhanced the modulus of the PNIPAM/LMPs hydrogel, triggering high mechanical stability during repeated swelling/deswelling behavior. Lastly, highly constricted PNIPAM/LMPs hydrogel provided a 5x10⁶ of electrical switching after deswelling, and the switching ratio was closely maintained after repeated swelling/deswelling transformation. This study opens up opportunities for hydrogel use requiring thermo-responsive and high electrical switching fields.

• Journal of Electrochemical Science and Technology
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• 제15권2호
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• pp.291-298
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• 2024

Due to its high theoretical capacity, Silicon (Si) has shown great potential as an anode material for lithium-ion batteries (LIBs). However, the large volume change of Si during cycling leads to poor cycling stability and low Coulombic efficiency. In this study, we synthesized Si/Carbon C45:Graphene composites using a ball-milling method with a fixed Si content (20%) and investigated the influence of the C45/Gr ratio on the electrochemical performance of the composites. The results showed that carbon C45 networks can provide good conductivity, but tend to break at Si locations, resulting in poor conductivity. However, the addition of graphene helps to reconnect the broken C45 networks, improving the conductivity of the composite. Moreover, the C45 can also act as a protective coating around Si particles, reducing the volume expansion of Si during charging/discharging cycles. The Si/C45:Gr (70:10 wt%) composite exhibits improved electrochemical performance with high capacity (~1660 mAh g^-1 at 0.1 C) and cycling stability (~1370 mAh g^-1 after 100 cycles). This work highlights the effective role of carbon C45 and graphene in Si/C composites for enhancing the performance of Si-based anode materials for LIBs.

• 보존과학회지
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• 제36권4호
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• pp.284-295
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• 2020

This study focuses on reinforcement agents for wall damage, such as cracks, breakage, or delamination, for mural paintings from the Payathonzu temple. Experiments were conducted with filling and grouting agents based on the reinforcing method. In the filling reinforcement experiment, different mixing ratios of lime to sand, and additives (jaggery, seaweed glue, and Primal SF-016) were used. In the grouting reinforcement experiment, the mixing ratio of lime and pozzolan was the same, and the additive types were identical to the filling reinforcement experiment. The filling reinforcement experiment showed that there were fewer physical changes such as contraction, with a greater mixing ratio of lime to sand, however, the compressive strength decreased as the mixing ratio increased. With additives, the change in volume of agent decreased and the compressive strength increased, which was especially prominent for jaggery and Primal SF-016. The grouting reinforcement experiment showed that there was a remarkable contraction with an increased amount of moisture that originates from the characteristic of grouting agents that requires flowability. With additives, the water content of the agent decreased, whereas the compressive strength and adhesion increased. Among the additives, Primal SF-016 exhibited the highest compressive strength, and seaweed glue exhibited the most considerable viscosity and adhesion. The study results showed that the characteristics of reinforcement agents vary according to the mixing ratio and additives of the filling and grouting agents. Therefore, it is necessary to selectively apply the mixing ratio and additives for different reinforcement agents considering the wall damage for conservation treatments.

• 한국식품조리과학회지
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• 제27권1호
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• pp.63-73
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• 2011

Cabbage (Baechu) Kimchi in its truncated form was placed in four different packing materials, Ny/PE/LLDP, OPP/AL/PE, PP and PET, and quality changes were observed during storage. Changes in pH and total acidity showed an x-shaped cross-curve as pH decreased and total acidity increased during storage. PP tray showed the slowest change at $5^{\circ}C$ with time. The pH was initially 6.25, but decreased to 4.12~4.16 at 20 days, and total acidity showed a 4 to 4.8-fold increase after 20 days of storage compared to the initial value. During storage at $5^{\circ}C$, total bacterial count and lactic acid bacterial count rapidly increased after 4 days. The total bacterial quantity decreased after a period of time and there were differences according to packaging material; OPP/AL/PE packaging showed the most dramatic decrease. Change in microbial count mostly followed a similar pattern to that of total acidity for all packaging materials. Changes in the color of Kimchi liquid, when examined by color index in $L{\cdot}b$/a form, rapidly decreased over time, similar to pH. Small Ny/PE/PP and OPP/AL/PE packages of Kimchi were examined for changes in free volume inside the packaging. After 13 days of storage at $5^{\circ}C$, the volume was 243 mL, but storage at $20^{\circ}C$ resulted in a volume of 372 mL, a more than 1.5-fold increase in free volume. There were changes in the quality characteristics of small package Kimchi according to storage temperature and packaging material, and large changes in pH, total acidity, and microbial count were evident upon storage at $5^{\circ}C$ for 8 days, which was the optimum palatability period. Mostly, PP treatment showed the slowest quality changes upon storage at $5^{\circ}C$. However, due to small package Kimchi's fast consumption system, the appropriate choice of packaging material must consider the product's turnover ratio. Further, the varieties of small package Kimchi should be diversified according to different consumer preferences by offering Kimchi with different maturity levels. Further, since the leading consumer base ranges in age from the teens to thirties, the development of various products targeting such consumers is necessary.

• 대한수의학회지
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• 제38권4호
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• pp.918-928
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• 1998

The present study was done with two aims. First, to evaluate the radiographic measurements of liver volumes in normal and hepatomegaly dogs induced by carbon tetrachloride. Second, to investigate quantitative tissue echo pattern by ultrasonography. Gray level histogram of the normal liver and the kidney were estimated with carbon tetra-chloride intoxication. In normal, r-square for liver volume to body weight was 0.93372, and this showed direct linear regression. Gray level histograms of the normal liver and the kidney were $19.150{\pm}2.490$(mean${\pm}$SD) and $13.175{\pm}2.686$(mean${\pm}$SD) respectively(p < 0.01). Liver parenchymal echogenicity was more hyperechogenic than kidney cortex echogenicity. Liver/Kidney ratio was $1.504{\pm}0.313$ and it can be used relative comparison of liver and kidney parenchymal echogenicity. In carbon-tetrachloride($CCl_4$) intoxication, changes of liver volume appeared to increase up to 24 hours after administration (p < 0.05), and decreased gradually to normal level after 2~5 days. Gray level histogram of liver parenchyma decreased up to 24hours (p < 0.01) after intoxication and then gradually increased to normal level. But that of kidney cortex had no significant change. Liver/Kidney ratio also decreased by 2 days(p < 0.01) and then gradually increased to normal level. On histopathologic features of hepatic tissues in carbon tetrachloride intoxication, both coagulative necrosis of hepatic cell and hemorrhage of centrilobular & midzonal area were identified. Conclusively, plain radiography is a useful diagnostic method for evaluating liver volume in mild hepatomegaly. Especially, it is considered that an adequate numerical processing of the liver length, depth and thoracic width and depth measurement would be helpful. Using gray level histogram, ultrasonographic evaluation was useful objective methods in early diagnosis of diffuse hepatic disease.