• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 2001.11a
• /
• pp.21-21
• /
• 2001

자원재활용과 원가절감를 위해 고지재활용율이 크게 상승하고 있으며, 이와 아울러 고 지원료로부터 고품질의 제품을 생산할 수 있는 기술에 대한 관심이 증대되고 있는 실 정이다. 저급 고지로부터 고품질의 탈묵펄프를 얻기 위해서는 고지재활용공정의 핵심 공정인 부유부상 공정의 효율화가 가장 중요하다고 믿어진다. 이를 위해서는 부유부상 공정에 가장 큰 영향을 미치는 고형입자의 표면 화학적 특성에 따른 공정의 분리효율 평가와 이에 근거한 공정해석과 개선이 요청된다. 이러한 부유부상 공정을 표면화학적 측면에서 구명하기 위해 마이크로 크리스탈린 셀룰로오스(Microcrystalline cellulose: M MCC)를 모댈 물질로 사용하여 표면화학적 특성은 다르나 입자의 크기와 형태는 동일 한 시료를 준비하였다. 친수성의 표면 특성을 나타내는 MCC의 표면 특성을 바꾸기 위 하여 AKD(alkyl ketene dimer)로 처리비율을 달리하여 솔벤트 사이징 처리를 실시하 였다. 이렇게 준비된 MCC의 표면화학적 특성을 IGC를 이용하여 평가하였다 .. IGC는 G GC를 응용한 표면분석 기술로 고체의 물리화학적 특성과 흡착성을 분석하기 위해서 사용되며 이로부터 흡착제의 표면특성을 평가할 수 있다. 본 실험에서는 AKD로 소수화 정도가 다르도록 소수화시킨 MCC 시료를 이용하여 I IGC 칼럼을 준비하고 n-알칸과 몇가지 극성 용매률 이용하여 이들의 칼럼 내 체류시 간을 측정함으로써 흡착특성을 평가하고 이로부터 흡착현상을 열역학적으로 분석하였다. IGC 분석 시에는 칼럼의 온도를 $30^{\circ}C$, $35^{\circ}C$, $40^{\circ}C$의 3수준으로 변화시켰다. 측정결 과로부터 MCC 표면의 흡착자유에너지와 엔탈피, 엔트로피의 변화량을 평가하였으며, 또한 MCC 표면의 극성에너지와 산염기적 성질을 평가하였다. 실험결과 MCC의 소수화도에 따른 열역학적 흡착현상의 차이가 명백하였다. 이는 소 수화 수준에 따라 소수성 및 친수성 물질의 흡착성이 변화된다는 것을 보여준다. 따라서 탈묵 시 진행되는 기포에의 부착현상을 평가할 수 있는 기초자료로 활용될 수 있다 고 사료되었다.

• Journal of the Korean Ceramic Society
• /
• v.33 no.8
• /
• pp.928-934
• /
• 1996

Quantitative analysis each portland cement components was conducted by standard calibration method using X-ray fluorescence spectrometer. Standard sample and the unknown sample were prepared by fused cast bead method. In checking the errors of standard cement 227A372 the relative errors of constituents such as CaO, SiO2, Al2O3, Fe2O3, MgO and SrO were less than 1% and the relative errors of constituents such as So3, K2O, TiO2, Na2O P2O5, and Mn2O3 were less than 5% Sample preparation was mainly contributed to the errors. Compared with general wet chemical method the results of X-ray fluorescence analyses were more precise and accurate. Moreover it is possible to analyze precisely a little amount of the constituents such as SrO, Mn2O3 and P2O5 the analyses of which were very difficult using the wet chemical method.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.7
• /
• pp.91-98
• /
• 2004

This paper presented results of the laboratory tests conducted to investigate ultrasonically enhanced flow rate using specially designed and fabricated equipment. Influencing factor, ${\alpha}_i$ was verified to investigate the effect of ultrasound on soil matrix and flowing liquid. The test conditions involve soil types, temperature and ultrasonic energy. The test results indicate that ultrasound enhances the flow rate significantly. The degree of enhancement and the values of influencing factors, however, vary with test conditions.

• Analytical Science and Technology
• /
• v.15 no.4
• /
• pp.346-359
• /
• 2002

The brominated flame retardants (BFRs) are one of the unregulated pollutants in Korea, which is recently highlighted the new pollutants of environmental contamination. In this study, the previous research papers related the BFRs were surveyed, and the analytical methods of BFRs were established. The results are followed; The 40 kinds of PBDEs standards were used to establish the analytical methods to perform the experiments of recoveries and detection limits in water and soil. The detection limits of PBDEs using GC/MS represented 5.0~10.0 pg/L for water and 0.5~2.0 ng/g for soil samples. The average recoveries of water samples were 89~98% with ethylacetate, n-hexane and dichloromethane, and 89~103% in combined solvent with n-hexane and acetone. In soxhlet extraction, the higher recoveries obtained the acetone:n-hexane(1:1) comparing with acetone:dichloromethane(1:1).

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.1
• /
• pp.338-344
• /
• 2021

In this study, an actual test procedure was considered for the effective operation of a bulletproof test. The problems of the existing system were drawn in two ways. First, it is difficult to mount items of various shapes. Second, various test standards cannot be applied. To improve these problems, an automated and standardized mounting system was designed/applied to mount various items. The multi-purpose mount was compatible with the backing support for body armor testing. The sample holding frame was located inside and was designed to mount samples of various sizes and shapes through vertical movement and fixation without a separate detachment/attachment process. A comparison of the economics before and after the introduction of the item mounting system confirmed the effectiveness of the system by the increased number of daily tests and equipment utilization and reduced hourly cost.

• Applied Chemistry for Engineering
• /
• v.28 no.3
• /
• pp.355-359
• /
• 2017

Zeolite X with Si/Al molar ratio = 1.08~1.20 was produced using a hydrothermal synthesis method. Ion-exchanged zeolite X samples were then prepared by using metal nitrate solutions containing $Mg^{2+}$ or $Cu^{2+}$. For all zeolite X samples, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS) were used to identify the change in crystal structure. The analysis of ammonia adsorption capability of zeolite X samples was conducted through the ammonia temperature-programmed desorption ($NH_3$-TPD) method. From XRD results, the prepared zeolite X samples maintained the Faujasite (FAU) structure regardless of cation contents in zeolite X, but the crystallinity of zeolite X containing $Mg^{2+}$ and $Cu^{2+}$ cations decreased. The distribution of cation contents in zeolite X was identified via EDS analysis. $NH_3$-TPD analysis showed that the $NH_3$ adsorption capacity of $Mg^{2+}$- and $Cu^{2+}$-zeolite X were 1.76 mmol/g and 2.35 mmol/g, respectively while the $Na^+$-zeolite X was 3.52 mmol/g ($NH_3/catalyst$). $Na^+$-zeolite X can thus be utilized as an adsorbent for the removal of ammonia in future.

• Analytical Science and Technology
• /
• v.13 no.2
• /
• pp.179-188
• /
• 2000

Trace elements in air samples artificially loaded on filters with urban dust and the bulk material of urban dust as an environmental sample were determined non-destructively using instrumental neutron activation analysis. Standard reference material (Urban Dust, SRM 1648) of the National Institute of Standard and Technology was used for the analytical quality control. The relative error for 37 elements was less than 15% and the standard deviation was less than 10%. 29 elements in the urban dust and 21 elements in the loaded filter sample were determined respectively. To evaluate the proficiency and reliability of the measurement, data intercomparison was performed and 39 analytical laboratories participated in the analysis using different analytical methods; neutron activation analysis, particle induced X-ray emission analysis, X-ray fluorescence analysis and atomic absorption spectrometry. Z-scores were calculated using the standard deviation of the laboratorie's mean as target standard deviation, and a good result was obtained that the values fall between -1 and +1 except some elements.

• Applied Microscopy
• /
• v.30 no.3
• /
• pp.241-248
• /
• 2000

Electron microscopy has used for analysing the structure of protein over 30 years. Bacteriohodopsin and porins are used as examples to illustrate the progress that has recently been made in attaining resolutions which hitherto were regarded as exclusive to the realm of x-ray crystallography. To determine a protein structure used by electron microscopy, one must pass through a number of basic steps including preparation of specimen , data acquisition and data processing.

• Journal of the Mineralogical Society of Korea
• /
• v.7 no.2
• /
• pp.128-137
• /
• 1994

예산-공주-청양 지역에는 여러 큰 규모의 활석 광상이 분포한다. 이 지역에서 산출되는 활석 광석은 초염기성암 기원의 사문암이 열수변질작용을 받아서 주로 생성된 것으로알려져 있으며 녹니석, 운모, 각섬석 등의 규산염 광물들은 불순물로 다량 함유하고 있다. 활성 광석에 포함되어 있는 이들 함철규산염 광물들을 분리해 내고 활석 광석의 품질을 향상시키기 위하여 고구려배자력분리방법을 실험적으로 적용함으로써 활석 광석의 정제법을 강구하고자 하였다. 활석광석을 구성하고 있는 광물들의 자기적, 광물학적 특성을 토대로 하여 인공 혼합 표준 시료와 활석 광석 시료를 준비하고 이들을 대상으로 각각 실험하였다. 정제 실험 결과 고구배자력분리기를 통과한 정광의 경우 활석의 양이 증가하였고 다른 불순광물들의 양은 현저히 감소하였으며 활석 광석의 백색도에 있어서는 대흥광산의 원광석의 경우 60.6에서 65.5로, 평안광산의 경우 61.6에서 65.0으로, 신양광산의 경우 71.2에서 74.5로 향상되었다.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 2006.04a
• /
• pp.205-210
• /
• 2006

본 논문은 내구성(durability) 및 내오염성(soiling resistance)이 중요한 용지에 있어 재현성 및 반복성이 우수하고 합리적인 측정방법을 구축하는데 목적이 있다. 연구목적에 적합한 시료의 준비, 오염물의 조성, 실험장치 및 실험후의 타당한 평가방법 등에 대하여 선행 연구결과를 고찰하였고 기존 방법의 수정과 새로운 장치의 제작 및 평가방법을 통해 재현성이 높은 평가방법을 정립할 수 있었다.