• 대한화학회지
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• 제19권2호
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• pp.142-146
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• 1975

황산제일철을 원료로 해서 함수산화철 안료를 제조하기 위한 실험이다. 황산제일철을 암모니아로 중화해서 Mohr's salt(ferrous ammonium sulfate)을 만들고 Mohr's salt의 농도를 Fe(II) 이온농도, 14${\sim}$72g/l, 수소이온농도를 pH3 또는 6으로 조절한뒤, 반응온도는 $90{\sim}100^{\circ}C$로 일정하게 유지하고 반응시간 2시간, 3기압으로 공기 가압한 결과는 다음과 같다. Mohr's salt의 농도가 진하고, 중성으로 갈수록 함수산화철의 수득율이 증가되며, Mohr's salt 농도가 Fe(II) 이온농도, 42.81g/l 일때, 91.5% 이상의 수득율을 얻었다. 이렇게하여 생성된 함수산화철의 결정형은 $\alpha$-goethite형이며, 색상도 천연 ${\alpha}$-goethite와 유사하였다. 이것을 $500^{\circ}C$로 하소(calcination)하니 미려한 적갈색을 띤 ${\alpha}-Fe_2O_3$가 생성되었다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2000년도 추계학술발표회 초록집
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• pp.1-2
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• 2000

In chip plating, several parameters must be taken into consideration. Current density, solution concentration, pH, solution temperature, components volume, chip and media ratio, barrel geometrical shape were most likely found to have an effect to the process yields. The 3 types of barrels utilized in chip plating industry are the onventional rotating barrel, vibrational barrel(vibarrel), and the centrifugal type. Conventional rotating barrel is a close type and is commonly used. The components inside the barrel are circulated by the barrel's rotation at a horizontal axis. Process yield has known to have higher thickness deviation. The vibrational barrel is an open type which offers a wide exposure to electrolyte resulting to a stable thickness deviation. It rotates in a vertical axis coupled with multi-vibration action to facilitate mixed up and easy transportation of components. The centrifugal barrel has its plated work centrifugally compacted against the cathode ring for superior electrical contact with simultaneous rotary motion. This experiment has determined the effect of barrel vibration intensity to the plating thickness distribution. The procedures carried out in the experiment involved the overall plating process., cleaning, rinse, Nickel plating, Tin-Lead plating. Plating time was adjusted to meet the required specification. All other parameters were maintained constant. Two trials were performed to confirm the consistency of the result. The thickness data of the experiment conducted showed thatbthe average mean value obtained from higher vibrational intensity is nearer to the standard mean. The distribution curve shown has a narrower specification limits and it has a reduced variation around the target value. Generally, intensity control in vi-barrel facilitates mixed up and easy transportation of components. However, it is desirable to maintain an optimum vibration intensity to prevent solution intrusion into the chips' internal electrode. A cathodic reaction can occur in the interface of the external and internal electrode. 2H20 + e $\rightarrow$M/TEX> 20H + H2.. Hydrogen can penetrate into the body and create pressure which can cause cracks. At high intensity, the chip's motion becomes stronger, its contact between each other is delayed and so plating action is being controlled. However, the strong impact created by its collision can damage the external electrode's structure there by resulting to bad plating condition.

• 대한환경공학회지
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• 제29권5호
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• pp.515-520
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• 2007

현재 슬러지의 처리는 주로 해양투기에 의해 진행되는데 런던협약에 의해 슬러지 내 중금속 함량에 따라 점진적으로 해양투기가 완전 금지되어진다. 이에 하수슬러지의 안정적 처리 방안이 시급히 검토되어야 한다. 그 대책으로 최근 슬러지의 능률적이고 친환경적인 처리를 위한 방법 중 하나로 활성화를 통한 흡착제 제조가 부각되고 있다. 본 연구는 하수슬러지를 수증기 활성화법을 이용하여 흡착제로 활용하기 위한 기초연구로서 양질의 흡착제를 제조하기 위한 변수별 연구를 통한 최적 활성화조건을 연구하였다. 그 결과 요오드 흡착능을 기준으로 하여 변수별 연구를 통해 수증기 주입량 30 mL/hr, 활성화 온도 $500^{\circ}C$, 활성화 시간 60분으로 선정되었다. 이 때 요오드 흡착능과 수율은 228.4 mg/g, 77.23%로 나타났다. 또한 질소 흡착, SEM, EDS를 이용하여 수증기 활성화에 따른 세공 발달, 비표면적, 평균 세공경 및 화학적 성상과 함량을 파악하였다. 수증기 활성화를 통해 발달되는 세공은 주로 미세 세공임을 확인하였다.

• 대한한방부인과학회지
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• 제25권2호
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• pp.108-119
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• 2012

Objectives: This study was performed to compare the differences between decoctions extracted by different extraction method and extraction time. Methods: Decoctions were prepared with pressurized or non-pressurized extraction for 60, 120 and 180min. The yield of extract, total soluble solid content, hydrogen ion concentration(pH) and the content of reference compound in Sipjeondaebo-tang (Siquandabu-tang) were investigated. Results: While yields and the total soluble solid of decoction were higher in pressurized method proportional to extraction time, pH values were lower in pressurized method and showed decreasing values with increasing extraction time. Albilflorin, ferulic acid, nodakenin, coumarin, cinnamaldehyde and glycyrrhizin were contained in decoctions by pressurized extraction method more than non-pressurized method whereas the content of coumarin was higher in decoctions by non-pressurized extraction method. In addition, coumarin was extracted increasingly with extraction time in decoctions by pressurized method, however, nine compounds except cinnamaldehyde showed the tendency of increasing proportional to extraction time. Conclusions: The results show that extraction methods including pressurized or non-pressurized extraction, and extraction time could affect the physicochemical characteristic or composition of Sipjeondaebo-tang(Siquandabu-tang) decoction.

• 공업화학
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• 제9권5호
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• pp.619-623
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• 1998

불화된 금속 산화물 촉매상에서 이염화메탄을 불화하여 이불화메탄을 합성하는 연구를 하였다. 실험 변수는 반응온도, HF/DCM (dichloromethane) 몰비, 접촉시간 그리고 촉매의 형태이었다. 촉매의 성능은 불화된 알루미나 보다는 크롬이 담지된 불화된 알루미나가 우수하였으며 크롬을 담지한 촉매에서 전처리 하지 않은 경우가 수소와 공기 분위기로 소성처리한 경우보다 더욱 우수하였다. 최적 반응 조건은 반응온도 $340^{\circ}C$, HF/DCM 몰비 5이상 그리고 접촉시간 20 초 이상이었다. 이들 조건에서 얻은 이불화메탄의 최대 수율은 80% 이상이었다. 특히 반응시간이 8시간까지 촉매의 활성 감소나 이불화메탄의 선택성의 감소가 나타나지 않았다.

• 공업화학
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• 제9권5호
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• pp.749-753
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• 1998

고급지방산 메틸에스테르의 일종인 dodecanoic acid methyl ester (DME)에 금속 산화물인 고체촉매 (W-7)를 이용하여 고온, 고압하에서 ethyleneoxide (EO)를 5, 7, 9, 및 12 몰씩 부가반응시켜 얻은 비이온성 계면활성제인 methoxy polyoxy ethylene dodecanoate (MPD)류 4종을 높은 수율 (93~97%)로 합성하여 얻었다. DME는 구조적으로 활성수소가 없어서 일반적인 산, 알칼리 촉매에서는 반응이 어렵고 활성고체촉매를 사용해야 EO의 단위 몰수를 부가 시킬 수 있었다. 최종 생성물에 대한 것을 IR, HPLC 및 $^1H$ NMR를 이용하여 각각의 화합물에 대한 구조를 확인하였다. 이 결과 EO의 부가 몰수는 5.2, 7.1, 9.2 및 12.1 몰이었고, 각 몰의 평균 EO 분포는 polyoxyethylene alkyl ether (AE)처럼 정규분포 곡선을 나타내었다.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.325-334
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• 2018

Lactose is a reducing disaccharide consisting of two different monosaccharides such as galactose and glucose. The hydrogenation of lactose to lactitol is a formidable challenge because it is a complex process and several side products are formed. In this work, we synthesized Ru-Ni bimetallic nanohybrids as efficient catalysts for selective lactose hydrogenation to give selective lactitol. Ru-Ni bimetallic nanohybrids with $Ru-NiO_x$ (x = 1, 5, and 10 wt%) are prepared by impregnating Ru and Ni salts precursors with $TiO_2$ used as support material. Ru-Ni bimetallic nanohybrids (represented as $5Ru-5NiO/TiO_2$) catalyst is found to exhibit the remarkably high selectivity of lactitol (99.4%) and turnover frequency i.e. ($374h^{-1}$). In contrast, monometallic $Ru/TiO_2$ catalyst shows poor performance with ($TOF=251h^{-1}$). The detailed characterizations confirmed a strong interaction between Ru and NiO species, demonstrating a synergistic effect on the improvement on lactitol selectivity. The impregnation-reduction method for the preparation of bimetallic $Ru-NiO/TiO_2$ catalyst promoted Ru nanoparticles dispersed on NiO and intensified the interaction between Ru and NiO species. $Ru-NiO/TiO_2$ efficiently catalyzed the hydrogenation of lactose to lactitol with high yield/selectivity at almost complete conversion of lactose at $120^{\circ}C$ and 55 bar of hydrogen ($H_2$) pressure. Moreover, $Ru-NiO/TiO_2$ catalyst could also be easily recovered and reused up to four runs without notable change in original activity.

• 미생물학회지
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• 제55권3호
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• pp.258-267
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• 2019

본 연구의 목적은 탈지유와 두유 내에서 Enterobacter aerogenes CIH05의 증식과 바이오제닉 아민(biogenic amines, BA) 생성량에 대한 유산균의 영향을 조사하는 것이다. 갓김치로부터 분리된 Lactobacillus acidophilus GK20, Lactobacillus paracasei GK74 및 Lactobacillus planatrum GK81은 탈카르복시화 배지 상에서 BA를 생성하지 않았다. 탈지유와 두유 내에서 L. paracasei GK74에 의해 가장 많은 생균수와 항균 물질 생성량이 측정되었고, 반면 L. plantarum GK81은 다른 균주들에 비해 유의하게 낮은 균수와 항균 물질을 생산하였다. 유산, 과산화수소 및 박테리오신의 생산량은 Lactobacillus의 균종과 배지 종류에 의존하였다. 유산균과 유사하게 E. aerogenes CIH05도 단독 배양 시 두유보다 탈지유에서 더 많은 균수가 측정되었다. 탈지유와 두유 내에서 L. acidophilus GK20이나 L. paracasei GK74와 혼합 배양하거나 박테리오신 용액(300 AU/ml)을 처리했을 때 E. aerogenes CIH05의 균수가 유의하게 감소되었고 히스타민과 카다베린의 생성도 효과적으로 억제되었다.

• 천문학회지
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• 제54권5호
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• pp.139-155
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• 2021

We present an updated version of the multilayer spectral inversion (MLSI) recently proposed as a technique to infer the physical parameters of plasmas in the solar chromosphere from a strong absorption line. In the original MLSI, the absorption profile was constant over each layer of the chromosphere, whereas the source function was allowed to vary with optical depth. In our updated MLSI, the absorption profile is allowed to vary with optical depth in each layer and kept continuous at the interface of two adjacent layers. We also propose a new set of physical requirements for the parameters useful in the constrained model fitting. We apply this updated MLSI to two sets of Hα and Ca II line spectral data taken by the Fast Imaging Solar Spectrograph (FISS) from a quiet region and an active region, respectively. We find that the new version of the MLSI satisfactorily fits most of the observed line profiles of various features, including a network feature, an internetwork feature, a mottle feature in a quiet region, and a plage feature, a superpenumbral fibril, an umbral feature, and a fast downflow feature in an active region. The MLSI can also yield physically reasonable estimates of hydrogen temperature and nonthermal speed as well as Doppler velocities at different atmospheric levels. We conclude that the MLSI is a very useful tool to analyze the Hα line and the Ca II 8542 line spectral daya, and will promote the investigation of physical processes occurring in the solar photosphere and chromosphere.

• 대한금속재료학회지
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• 제47권3호
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• pp.175-181
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• 2009

Mechanical properties and precipitation behavior of backward extruded 6061 Al alloy for pressure vessel were investigated using tensile test, transmission electron microscopy (TEM) and differential scanning calorimeter (DSC). In this study, solution heat treatment (SHT) was performed at $535^{\circ}C$ for 30~90 min and aging treatment was conducted at 177 and $190^{\circ}C$ for 1~7 h. Maximum tensile strength of $36.6kgf/mm^2$ and yield strength of $33.29kgf/mm^2$ were achieved at the aging time of 5 h at $190^{\circ}C$. TEM observation showed that fine needle-like ${\beta}^{{\prime}{\prime}}$ phase which has 35~45 nm of length was uniformly distributed in the aged 6061 Al alloy specimen. From tensile test, TEM and DSC analysis, it is expected that aging time of 2~5 h at $190^{\circ}C$ is suitable for the extruded A6061 used as pressure vessels.