• 한국안전학회지
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• 제29권4호
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• pp.61-72
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• 2014

The aim of this study is to define the condition of optimal pre-treatment for preferable activated carbon fibers (ACFs), which are based on rayon fibers. This paper shows the ideal path of ACFs preparation process; implies that rayon fibers are pre-treated by various solvents with different times before the heating process. The pre-treated rayon fibers finally turned into desirable rayon fiber-based ACFs through optimal pre-treatment condition by heating processes. The thermal analysis method of pre-treated rayon fibers by thermo-gravimetry analyser (TGA) is an idealized tool, which analyzes the best thermal condition of pre-treatment process. Surface morphologies of resulting rayon fibers based ACFs were examined by scanning electron microscope(SEM). The results of TGA and SEM analyses show that the optimal pre-treatment condition for preparing ACFs was clearly defined, in terms of thermal stability and surface morphology.

• 상하수도학회지
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• 제38권2호
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• pp.109-117
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• 2024

In this study, various pre-treatment methods were evaluated for microalgae separation. These methods aimed to facilitate safe, rapid, and cost-effective online imaging for real-time observation and cell counting. As pre-treatment techniques, heating, chemical hydrolysis, heating combined with chemical hydrolysis, and sonication were employed. The effectiveness of these methods was evaluated in the context of online imaging quality through experimentation on cultivated microalgae (Chlorella vulgaris and Scenedesmus quadricauda). The chemical treatment method was found to be inappropriate for improving image acquisition. The heating pre-treatment method exhibited a drawback of prolonged cell dispersion time. Additionally, the heating combined with chemical hydrolysis method was confirmed to have the lowest dispersion effect for Chlorella vulgaris. Conversely, ultrasonication emerged as a promising technique for microalgae separation in terms of repeatability and reproducibility. This study suggests the potential for selecting optimal pre-treatment methods to effectively operate real-time online monitoring devices, paving the way for future research and applications in microalgae cultivation and imaging.

• Environmental Engineering Research
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• 제22권1호
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• pp.12-18
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• 2017

Struvite precipitation has been proven to be an effective method in removing and recovering ammonia nitrogen (N) and phosphate phosphorus (P) from wastewater. In this study, effects of pH, molar ratios and pre-treatment of effluent of anaerobically digested swine wastewater were investigated to improve struvite crystallization. The magnesium : ammonium : phosphate ratio of 1.2 : 1.0 : 1.0 was found to be optimal, yet the molar ratio in the wastewater was 1 : 74.9 : 1.8. From the analysis, the optimum pH was between 8.0 and 9.0 for maximal phosphate P release and from 8.0 to 10.0 for maximal ammonia N and phosphate P removal from real wastewater. Analysis from Visual MINTEQ predicted the pH range of 7-11 for ammonia N and phosphate P removal and recovery as struvite. For pre-treatment, microwave pre-treatment was ineffective for phosphate P release but ultrasound pre-treatment showed up to 77.4% phosphate P release at 1,000 kJ/L of energy dose. Precipitates analysis showed that phosphorus and magnesium in the collected precipitate had almost same values as theoretical values, but the ammonia content was less than the theoretical value.

• 한국환경보건학회지
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• 제35권5호
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• pp.402-410
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• 2009

This study was carried out to examine the optimal analytical method for determination of urinary toxic arsenic (inorganic arsenic and its metabolites) by HG-AAS (hydride generation-atomic absorption spectrometry). In the analysis of SRMs (standard reference materials), method E (addition of 0.4% L-cysteine to pre-reductant and use 0.04M HCl as carrier acid) showed the most accurate results compared with the reference values. In the analysis of 30 urinary samples, analytical results were significantly different depend on the component of pre-reductant and the concentration of carrier acid. When the concentration of carrier acid was higher, the analytical result was lower. The recovery rates of MMA (monomethylarsonic acid) and DMA (dimethylarsenic acid) were varied by the concentration of pre-treatment acid and carrier acid and hydride generation reagents. When the concentration of carrier acid was 1.62 M (5% HCl), the recovery rates of DMA was 1%. The recovery rates of MMA and DMA in method E (=V) were 102% and 100%, respectively. The results of this study suggest that the component and concentration of pre-reductant and carrier acid must be carefully adjusted in the analysis of urinary arsenic, and method E is recommendable as the most precise analytical method for determination of urinary toxic arsenic.

• 펄프종이기술
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• 제44권6호
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• pp.36-42
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• 2012

The empty fruit bunch fibers(EFB) of oil palm were examined for optimal utilization of the EFB fibers. The EFB fibers were obtained by shredding EFB, followe by removal of fines. The surface properties of the fibers were modified with various pre-treatments, such as hot water extraction, the soaking treatments with NaOH, $ClO_2$ and n-hexane. The changes in the fiber surface were examined with FT-IR method, which showed the changes in chemical compositions such as pectin, lignin, and etc. according to the pre-treatment methods. And the z-directional tensile testing of the fiber mold made of the treated EFB fibers showed the changes in the bonding strength by the pre-treatments. The fiber mold made of EFB fibers treated with $ClO_2$ showed the greater increase in the tensile energy absorption although the NaOH treatment resulted in the severer impact on the EFB fibers.

• 한국축산식품학회지
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• 제43권3호
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• pp.428-440
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• 2023

Global meat consumption is increasing worldwide, however, supply remains lacking. Several alternative protein sources, such as cultured meat, plant-based protein production, and edible insects, have been proposed to overcome this shortage. Interestingly, edible insects are characterized by superior digestive and absorptive qualities that make them the ideal replacement for traditional protein production. This study aims to further the processing ability of insect protein by investigating the effects of various pre-treatment methods, such as blanching (HB), roasting (HR), and superheated steam (HS), on the nutritional properties and physicochemical characteristics of proteins extracted from Hermetia illucens larvae. The drying rate, pH value, color analysis, amino and fatty acid profile, as well as bulk density, shear force, and rehydration ratios of the above pre-treatment methods, were explored. HS was found to have the highest drying rate and pH value analysis showed that HB and HS samples have significantly higher values compared to the other modalities. Raw edible insects had the highest value in the sum of essential amino acid (EAA) and EAA index when compared to EAAs. HB and HS showed significantly lower bulk density results, and HS showed the highest shear force and the highest value in rehydration ratio, regardless of immersion time. Therefore, taking the above results together, it was found that blanching and superheated steam blanching pre-treatment were the most effective methods to improve the processing properties of H. illucens after hot-air drying.

• 펄프종이기술
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• 제45권1호
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• pp.75-82
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• 2013

The traditional Hanji-making was confronted with lots of industrial disadvantages and economic problems, due to the original hand-made process. Recently, the studies on the automation of overall Hanji manufacturing process is carried out by applying the commercial chemical pulping method in order to expand industrial application or efficiency of non-wood fibrous materials. However, the application of commercial pulping methods to the bast tissues of paper mulberry leads to the chemical and mechanical deterioration of cellulosic fibers. In this study, the optimal cooking method using the bast parts of paper mulberry produced by an auto-scraping device was applied to minimize the damage of fiber strength for the paper yarn manufacture. The pre-steaming treatment and alkaline pulping systems were evaluated in removal efficiency of lignin and pectin materials within the bast tissue of paper mulberry. With the application of pre-steaming treatment and 2 stage pulping system using potassium carbonate and then sodium hydroxide, kappa values were decreased two times more in lignin removal than the single stage of pulping method. It was also identified from SEM images and ATR-FTIR spectra that the pectin components within cellular structure of bast tissue were easily removed and the debarked bast parts by a auto-scraping device were easily defiberized by 2-stage pulping sequence using potassium carbonate/sodium hydroxide pulping system.

• 한국산학기술학회논문지
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• 제17권3호
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• pp.73-78
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• 2016

본 연구에서는 STS316 스테인리스강에 가스텅스텐아크용접을 수행하였다. 더블토치 장치를 이용하여 스텔라이트계 육성용접을 실시하였고, 다구찌 기법을 적용하여 경도 측정값에 대한 응답변수를 산출하여 공정 최적화를 도출하였다. 또한 이 공정변수가 육성용접의 특성에 미치는 영향을 분석하였다. 다구찌 기법에 의한 육성용접의 공정설계에 있어서 다중응답 변수를 고려한 최적공정설계는 매우 유효한 것을 확인할 수 있었다. 또한 각각의 응답변수에 대한 공정변수의 기여도 및 기여도에 대한 영향을 손쉽게 분석할 수 있었다. 육성용접에서 중요한 기계적 특성 요소인 경도값을 고려한 최적공정 조건은 전류 105 A, 전압 18V, 예열온도 $200^{\circ}C$, 후열온도 $100^{\circ}C$로 확인 되었다. 더블토치를 이용한 가스텅스텐아크용접의 최적조건에서 제작된 시험편의 경우 단일 토치를 사용 하였을 때 보다 더블토치를 사용하는 조건에 의해 제작된 시험편의 경우 경도는 8.19% 높은 양호한 특성을 나타내었다.

• Journal of Dental Anesthesia and Pain Medicine
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• 제17권2호
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• pp.91-103
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• 2017

General anesthesia is commonly used to facilitate dental treatment in patients with anxiety or challenging behavior, many of whom are children or patients with special needs. When performing procedures under general anesthesia, dental surgeons must perform a thorough pre-operative assessment, as well as ensure that the patients are aware of the potential risks and that informed consent has been obtained. Such precautions ensure optimal patient management and reduce the frequency of morbidities associated with this form of sedation. Most guidelines address the management of pediatric patients under general anesthesia. However, little has been published regarding this method in patients with special needs. This article constitutes a review of the current literature regarding management of patients with special needs under general anesthesia.

• Korean Chemical Engineering Research
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• 제47권6호
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• pp.762-767
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• 2009

해외 열대작물 씨앗에서 추출한 식물성 오일을 이용하여 바이오디젤을 생산하고 물성분석을 통해 차량연료로서의 사용가능성을 검토하는 연구를 수행하였다. 유리지방산 함량이 높은 열대작물 오일의 효율적인 바이오디젤 생산을 위해서는 유리지방산을 산촉매로 에스테르화한 후 전이에스테르화 반응하는 2단계 반응공정의 적용이 필요하였다. 전처리(에스테르화) 반응에 적합한 촉매를 선정하기 위해 3가지 산 촉매의 비교실험 수행 결과 황산이 최적 촉매임을 확인하였고, 반응표면분석법(response surface method, RSM)에 의해 도출한 최적 반응조건은 황산 촉매 0.982%와 메탄올 26.7%로 나타났다. 전이에스테르화 반응에 대한 최적화 실험을 반응표면분석법에 근거하여 수행하고, 결과로 KOH 촉매 1.24%, 메탄올 22.76%로 확인되었지만 본 연구팀의 선행 실험의 반응조건(KOH 0.8%)보다 과량의 촉매가 투입된 것으로 나타났다. 이에 대한 확인실험으로 메탄올과 촉매 투입량에 대한 추가 실험을 수행하였으며, 그 결과로서 최적 반응조건으로 KOH 촉매 0.8%와 메탄올:오일 몰비 6.2:1로 도출하였으며 반응생성물의 분석결과 지방산 메틸에스테르(fatty acid methyl ester, FAME) 100.8%, 산가 0.45 mgKOH/g, 수분 0.00%, 산화안정성 0.70 h, 총 글리세롤 함량 0.04%, Mono-glyceride 함량 0.04%, Di-glyceride 함량 0.01%, Tri-glyceride 함량 0.00%, 동점도($40^{\circ}C$에서) $4.041mm^2/s$, 저온필터막힘점 $1.0^{\circ}C$로 주요 바이오디젤 품질규격을 만족하는 것으로 나타났다.