• 한국세라믹학회지
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• 제28권11호
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• pp.843-850
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• 1991

There is a growing demend for absorptive electromagentic shielding materials for wide band frequency application. In this study, the absorber which consists of a rubber plus Ni-Zn ferrite which have been prepared by direct-wet method. A rubber ferrite composite for electromagnetic shielding, it is most importan facter the homogeneous ultra fine size and high dispersitive ferrite powder. Direct-wet method and solid-solid reaction method for preparing of ultra fine ferrite powder was used. It has been experimentally verified that the powder which prepared by direct-wet method was very fine and almost same size spherical powder, the composite ferrite have excellent electromagnetic wave absorption in X-band.

• Journal of Korean Neurosurgical Society
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• 제66권5호
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• pp.536-542
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• 2023

Objective : Surgical site infection is the most detrimental complication following cranioplasty. In other surgical fields, intrawound vancomycin powder application has been introduced to prevent surgical site infection and is widely used based on results in multiple studies. This study evaluated the effect of intrawound vancomycin powder in cranioplasty compared with the conventional method without topical antibiotics. Methods : This retrospective study included 580 patients with skull defects who underwent cranioplasty between August 1, 1998 and December 31, 2021. The conventional method was used in 475 (81.9%; conventional group) and vancomycin powder (1 g) was applied on the dura mater and bone flap in 105 patients (18.1%; vancomycin powder group). Surgical site infection was defined as infection of the incision, organ, or space that occurred after cranioplasty. Surgical site infection within 1-year surveillance period was compared between the conventional and vancomycin powder groups with logistic regression analysis. Penalized likelihood estimation method was used in logistic regression to deal with zero events. All local and systemic adverse events associated with topical vancomycin application were also evaluated. Results : Surgical site infection occurred in 31 patients (5.3%) and all were observed in the conventional group. The median time between cranioplasty and detection of surgical site infection was 13 days (range, 4-333). Staphylococci were the most common organisms and identified in 25 (80.6%) of 31 cases with surgical site infections. The surgical site infection rate in the vancomycin powder group (0/105, 0.0%) was significantly lower than that in the conventional group (31/475, 6.5%; crude odds ratio [OR], 0.067; 95% confidence interval [CI], 0.006-0.762; adjusted OR, 0.068; 95% CI, 0.006-0.731; p=0.026). No adverse events associated with intrawound vancomycin powder were observed during the follow-up. Conclusion : Intrawound vancomycin powder effectively prevented surgical site infections following cranioplasty without local or systemic adverse events. Our results suggest that intrawound vancomycin powder is an effective and safe strategy for patients undergoing cranioplasty.

• 한국분말재료학회지
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• 제27권4호
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• pp.300-304
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• 2020

In this paper, a durability study is presented to enhance the mechanical properties of an Fe-Si-Al powder-based magnetic core, through the addition of graphite. The compressive properties of Fe-Si-Al-graphite powder mixtures are explored using discrete element method (DEM), and a powder compaction experiment is performed under identical conditions to verify the reliability of the DEM analysis. Important parameters for powder compaction of Fe-Si-Al-graphite powder mixtures are identified. The compressibility of the powders is observed to increase as the amount of graphite mixture increases and as the size of the graphite powders decreases. In addition, the compaction properties of the Fe-Si-Al-graphite powder mixtures are further explored by analyzing the transmissibility of stress between the top and bottom punches as well as the distribution of the compressive force. The application of graphite powders is confirmed to result in improved stress transmission and compressive force distribution, by 24% and 51%, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.126-129
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• 2009

In this study, it was aimed to develop the re-use technology of ultra-fine silicon powders, by-products during the current production process of high purity poly-Si feedstock. For this goal, the compacts of the silicon powders were tried to fabricate by CIP (Cold Isostatic Pressing) method using silicon rubber mold without chemical binder materials. The density ratio of the silicon powder compacts reached 74%. In order to simulate the actual handling and charging conditions of feedstock material in casting process, a shaking test was carried out and mass loss measured. Finally, the silicon powder compacts were melted using a cold crucible induction melting method and the purity assessment was conducted by Hall effect measurement.

• 한국분말재료학회지
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• 제25권4호
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• pp.309-315
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• 2018

In the present work, we synthesize nano-sized ZnO, $SnO_2$, and $TiO_2$ powders by hydrothermal reaction using metal chlorides. We also examine the energy-storage characteristics of the resulting materials to evaluate the potential application of these powders to dye-sensitized solar cells. The control of processing parameters such as pressure, temperature, and the concentration of aqueous solution results in the formation of a variety of powder morphologies with different sizes. Nano-rod, nano-flower, and spherical powders are easily formed with the present method. Heat treatment after the hydrothermal reaction usually increases the size of the powder. At temperatures above $1000^{\circ}C$, a complete collapse of the shape occurs. With regard to the capacity of DSSC materials, the hydrothermally synthesized $TiO_2$ results in the highest current density of $9.1mA/cm^2$ among the examined oxides. This is attributed to the fine particle size and morphology with large specific surface area.

• 전기학회논문지
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• 제58권2호
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• pp.327-331
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• 2009

Nano-porous $TiO_2$ powder was fabricated using Acetylene black, applied photo voltaic device based on the Dye-sensitized Solar Cells (DSCs) was investigated experimentally. $TiO_2$-powder was fabricated using Ti-isopropoxide and 2-propanol by sol-gel combustion method. For cases of variable Acetylene black, characteristic of porosity, size of particle and crystallite of obtained $TiO_2$ nano-powder was investigated. The photovoltaic efficiency of the prepared DSCs was measured using $TiO_2$ film which prepared on each different heat treatment temperature($400^{\circ}C{\sim}700^{\circ}C$) with paste of $TiO_2$ powder. The porosity and size of particle of $TiO_2$ powder made with Acetylene black 0.4g was influenced significantly effect to DSCs characteristic. Heat treatment at $500^{\circ}C$ makes the better photovoltaic efficiency which 5.02%($J_{sc}=11.79mA/cm^2$, $V_{oc}=0.73V$, ff=0.58). The sol-gel combustion method was useful to DSCs fabrication.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1989년도 춘계학술대회 논문집
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• pp.77-80
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• 1989

The aim of the study is to develope the processing technique of PZT-Polymer piezoelectric composite materials for ultrasonic transducer application such as biomedical probe and hydrophone. Piezoelectric composite of PZT and polymer with 1-3 connectivity patterns have been fabricated by dicing-filling method and extrusion forming method. In this study processing forming method. In the study processing steps by extrusion forming method in the preperation of PZT/polymer piezoelectric composites are described. The PZT powder used in the study is commercial powder which is prepared by mixing PbO, TiO$_2$ and ZrO$_2$. The binder, water and plasticizer are mixed with the PZT powder to form a slip. It is necessary to adjust the viescosity of slip according on the PZT rod diameters to be extruded. The electromechanical properties of the piezoelectric composites are characterized in terms of the thickness resonance mode. The pulse response characteristics by the ultrasonic transducer analyzer and osciloscope are evaluated.

• 한국약용작물학회지
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• 제12권6호
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• pp.454-458
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• 2004

잇꽃 종실의 품질 향상에 효과적인 황 시용방법을 구명하고자 황분말 20 kg/10a와 유안의 시용방법 및 시용량을 달리하여 종실의 영양적 품질에 미치는 영향을 비교 조사한 결과는 다음과 같다. 1. 종실의 질소와 황 함량은 황 무시용구에 비해 시용구에서 높은 경향이었다. 황 처리간에는 질소 함량은 차이가 없었으나, 황 함량은 유안 토양시비량이 증가할수록 높아졌다. 유안 시비방법 간에는 토양시비 33 kg/10a와 엽면시비 간에 큰 차이는 없었다. 질소/황 비율은 황 시용으로 질소/황 비율이 저하되었고, 유안 토양시비 간에는 시용량이 증가할수록 감소하여 유안 49.5 kg/10a 처리시 가장 낮았다. 2. 종실의 조지방과 조단백질 함량은 황 시용시 무시용에 비하여 높았으며, 황 유형 간에는 조지방이 유안 엽면시비에서 가장 높았고, 조단백질이 유안 16.5 kg/10a에서 가장 낮았던 것을 제외하고 차이가 없었다. 3. 총페놀성 화합물 함량과 항산화 활성은 황 시용으로 증가하였다. 황 처리 간에는 총페놀성 화합물 함량은 차이가 없었으나, 항산화 활성은 황분말과 유안 33.0 kg/10a 처리에서 다소 높았다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1997년도 특별강연 및 추계학술발표 개요집
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• pp.119-121
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• 1997

No Abstract, See Full Text

• 한국축산식품학회지
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• 제33권5호
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• pp.672-677
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• 2013

The aim of this study was to develop sample preparation method and evaluate the exact cholesterol content in egg and egg powder purchased from Korean markets, and to determine whether significant differences exist among various egg products, since a variety of products are available in Korean markets and there are no recent databases for cholesterol. To evaluate the cholesterol content in chicken egg sold in Korean local market, a simple method using non-heated saponification to determine cholesterol for emulsified foods was applied. The results of recovery for egg and egg powder were in a range of 92.4-105.0%, with a relative standard deviation between 1.1% and 2.8% by using gas chromatography-flame ionization detector. Therefore, the total cholesterol content in whole egg was estimated between 160.8 and 226.3 mg/egg (AV(average) $186.8{\pm}3.5$), which is similar or lower than previously reported levels. The value for cholesterol in egg powder was estimated between 2.94 and 3.49 mg/g (AV $3.23{\pm}0.15$). We suggested method that can be applicable to chicken egg and egg powder matrix as providing rapid and accurate determination of cholesterol in egg and egg powder. This information will be helpful for processed food producers for deciding food labels of cholesterol content.