Hydrogen Absorption by Mg-Ni-Fe_2O_3 and Mg-Ni-Ti during Mechanical Grinding under Hydrogen

곽영준,박혜령,송명엽 대한금속·재료학회 2012 대한금속·재료학회지 Vol.50 No.11

Samples with compositions of 80 wt% Mg-14 wt% Ni-6 wt% Fe_2O_3 and 80 wt% Mg-14 wt% Ni-6 wt%Ti were prepared by mechanical grinding under hydrogen (reactive mechanical grinding). Their hydrogen absorptions during reactive mechanical grinding were examined. TGA and BET analysis were employed to investigate the hydrogen storage properties of the prepared alloys. TGA analysis of the Mg-14Ni-6Fe_2O_3showed an absorbed hydrogen quantity of 6.91 wt% while that of Mg-14Ni-6Ti was 2.59 wt%. BET analysis showed that the specific surface areas of Mg-14Ni-6Fe_2O_3 and Mg-14Ni-6Ti after reactive mechanical grinding were 264 ㎡/g and 64 m2/g, respectively. The larger absorbed hydrogen quantity and the larger specific surface area of Mg-14Ni-6Fe_2O_3 after RMG than those of Mg-14Ni-6Ti after RMG showed that the effects of Fe_2O_3addition are much stronger than those of Ti addition during reactive mechanical grinding.

농산물의 올바른 유통

곽영준 慶北大學校 農業開發大學院 2003 最高農業經營者課程 論文集 Vol.9 No.-

Photosensitive material in patterning for positive-tone photoresists

곽영준,이승우,손석호,석웅철,김기승 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.1

Hydrogen-storage properties of MgH2–10Ni–2NaAlH4–2Ti–2CNT milled in a planetary ball mill under H2

곽영준,송명엽,이병수,박혜령 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.6

A sample with a composition of 84 wt% MgH2–10 wt% Ni–2 wt% NaAlH4–2 wt% Ti–2 wt% CNT (named MgH2–10Ni–2NaAlH4–2Ti–2CNT) was prepared by milling in a planetary ball mill under H2. Activation of the sample was not required. At the first cycle, the sample absorbed 3.75 wt% H for 10 min, and 4.17 wt% H for 60 min at 593 K under 12 bar H2. Reactive mechanical grinding of Mg with Ni, NaAlH4, Ti,and CNT is thought to create defects on the surface and in the interior of Mg, as well as to reduce Mg particle size.

Comparison of Hydrogen-Storage Properties of Mg-14Ni-3Fe2O3-3Ti and Mg-14Ni-2Fe2O3-2Ti-2Fe

곽영준,박혜령,송명엽 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.3

Magnesium with oxides or transition elements prepared by mechanical grinding under H2 (reactive mechanical grinding) showed relatively high hydriding and dehydriding rates when the content of additives was about 20 wt%. Ni, Fe2O3, and Fe were chosen as the oxides or transition elements to be added. Ti was also selected since it was considered to increase the hydriding and dehydriding rates by forming Ti hydride. Samples Mg-14Ni-3Fe2O3-3Ti (Sample A) and Mg-14Ni-2Fe2O3-2Ti-2Fe (Sample B) were prepared by reactive mechanical grinding, and their hydrogen storage properties were compared. The activated Sample A had a little smaller hydriding rate than the activated Sample B, but a higher dehydriding rate than the activated Sample B. Sample A exhibits quite a larger dehydriding rate and quantity of hydrogen desorbed for 60 min than any other Mg-xNi-yFe2O3-zM (M=transition metals) samples. An addition of a relatively larger amount of Ti is considered to lead to quite a high hydriding rate and a high dehydriding rate of Sample A.

Preparation of Zn(BH4)2 and Diborane and Hydrogen Release Properties of Zn(BH4)2+xMgH2 (x=1, 5, 10, and 15)

곽영준,권성남,송명엽 대한금속·재료학회 2015 METALS AND MATERIALS International Vol.21 No.5

Zn(BH4)2 was prepared by milling ZnCl2 and NaBH4 in a planetary ball mill under Ar atmosphere, and Zn(BH4)2 +xMgH2 (x=1, 5, 10, and 15) samples were prepared. Diborane (B2H6) and hydrogen release characteristics of the Zn(BH4)2 and Zn(BH4)2+xMgH2 samples were studied. The samples synthesized by milling ZnCl2 and NaBH4 contained Zn(BH4)2 and NaCl, together with small amounts of ZnCl2 and NaBH4. We designated these samples as Zn(BH4)2(+NaCl). The weight loss up to 400 °C of the Zn(BH4)2(+NaCl) sample synthesized by milling 4 h was 11.2 wt%. FT-IR analysis showed that Zn(BH4)2 was formed in the Zn(BH4)2(+NaCl) samples. MgH2 was also milled in a planetary ball mill, and mixed with the Zn(BH4)2(+NaCl) synthesized by milling for 4 h in a mortar and pestle. The weight loss up to 400 °C of Zn(BH4)2(+NaCl)+MgH2 was 8.2 wt%, corresponding to the weight % of diborane and hydrogen released from the Zn(BH4)2(+NaCl)+MgH2 sample, with respect to the sample weight. DTA results of Zn(BH4)2(+NaCl)+xMgH2 showed that the decomposition peak of Zn(BH4)2 was at about 61 °C, and that of MgH2 was at about 370-389 °C.

연약지반의 상대적 침하 거동 분석

곽영준,한희수 대한지질공학회 2023 지질공학 Vol.33 No.2

Instruments are installed in soft ground improvement projects to manage economic and safe construction. When analyzing data, the amount of settlement data over time can be used to understand the overall ground settlement behavior, but it is difficult to analyze the interrelatedness between measurement points. Therefore, to analyze the relative compressive settlement behavior between measurement points, the settlement amount and velocity were processed and defined as the mean settlement difference index (  ) and the slope difference index ( ). Plotted in the mean settlement difference index - slope difference index (  -   ) coordinate system. As a result of the analysis of the relative compaction subsidence behavior between the measuring points, the relationship between the measuring points in the average subsidence difference index - slope difference index coordinate system moved to area 1 as the compaction was completed. By continuously plotting the movement path of the observation point in the corresponding coordinate system, the relative settlement behavior between the measurement points was analyzed, and it was possible to check whether the settlement behavior of the two measurement points was stable or unstable depending on the direction of the path. 연약지반 개량공사 시 계측기를 설치하여 경제적이고 안전한 시공이 이루어지도록 관리한다. 데이터 분석 시 시간에 따른 침하량 데이터를 활용하여 전체적인 지반 침하 거동을 파악할 수 있지만, 계측지점 간상호관련성을 분석하기에는 어려움이 있다. 따라서 계측지점 간의 상대적인 압밀침하 거동을 분석하기위하여, 침하량과 속도를 가공하여 평균 침하량 차이 지수와 기울기 차이 지수로 정의한 후, 평균 침하량차이 지수 - 기울기 차이 지수(  -   ) 좌표계에 도시하였다. 계측지점 간 상대적인 압밀침하 거동 분석결과 평균 침하량 차이 지수 - 기울기 차이 지수 좌표계에 나타낸 계측지점 간의 관계가 압밀이 완료됨에 따라 영역 1로 이동하였다. 관측점의 이동 경로를 해당 좌표계에 연속적으로 나타냄으로써 계측지점 간의 상대적인 압밀침하 거동관계를 분석하였으며, 이동경로 방향에 따라 두 계측지점의 압밀침하거동관계가 안정한 상태인지 불안정한 상태인지 확인할 수 있었다.

Synthesis and characterization of polybenzoxazoles for positive-tone photoresists

곽영준,이승우,석웅철,박주현,손석호 한국고분자학회 2015 한국고분자학회 학술대회 연구논문 초록집 Vol.2015 No.10

Electrochromic Properties of Polyimides Prepared from Methyl Substituted Triphenylamine Moiety with Different Dianhydrides

곽영준,이명준,석웅철,김준표,박주현,이승우 한국고분자학회 2015 한국고분자학회 학술대회 연구논문 초록집 Vol.2015 No.4

군집분류를 이용한 흙막이 벽체 배면 지반의 상대적 침하거동 분석

곽영준,한희수 대한지질공학회 2023 지질공학 Vol.33 No.1

As urbanization and industrialization increase development in downtown areas, damage due to ground settlement continues to occur. Building collapse in urban has a high risk of leading to large-scale damage to life and property. However, there has rarely been studied on measurement data analysis methods when uneven loads are applied to the excavated ground and no prior knowledge of the ground. Accordingly, it was attempted to analyze the relative settlement behavior and correlation by processing the time-series surface settlement of construction sites in the urban. In this paper, the average index of difference in settlement and average of relative difference in settlement are defined and calculated, then plotted in the coordinate system to analyze the relative settlement behavior over time. In addition, since there was no prior knowledge of the ground, a standard to classify the clusters was needed, and the observation points were classified into using k-means clustering and Dunn Index. As a result of the analysis, it was confirmed that all the clusters moved to the stable region as the settlement amount converges. The clusters were segmented. Based on the analysis results, it was possible to distinguish between the independent displacement area and same behavior area by analyzing the correlation between measurement points. If possible to analyze the relative settlement behavior between the stations and classify the behavior areas, it can be helpful in settlement and stability management, such as uplift of the surrounding area, prediction of ground failure area, and prevention of activity failure. 도시화와 산업화에 따라 도심지에 개발이 늘어나면서 지반침하로 인한 피해가 지속적으로 발생되고 있으며, 도심지에서의 건물붕괴는 대규모 인명 및 재산 피해로 이어질 위험이 크다. 굴착지반에 균등하지않은 하중이 작용하고, 대상지반의 사전지식이 없는 경우의 지반거동에 대해서는 연구가 거의 이루어지지 않았다. 이에 따라 지반 조사 정보가 없는 흙막이 공사의 굴착 과정에서 발생되는 배면 지반의 침하거동을 분석하는 방법이 기존에는 없었고, 본 연구에서는 시계열 데이터를 가공하여 상대적 침하거동과상호관련성을 분석하여 흙막이 벽체 배면 지반의 침하거동을 분석하고자 하였다. 본 논문에서는 평균침하량차지수와 평균상대침하량차를정의 및 계산하였으며, 이를 좌표계에 도시하여 시간경과에 따라 측점간의 상대적 침하거동을 분석하였다. 또한 관측점들의 군집을 분류할 수있는 기준이 필요하여 k-평균군집분석과 Dunn Index를 이용하여 분류하였다. 분석결과 계측지점의 침하량이 일정한 값으로 수렴하면서 모든 군집들이 안정영역으로 이동한 것을 확인할 수 있었으며, 군집은 세분화되었다. 이러한 분석결과를 바탕으로 연구대상의 각 측점 간 상관관계를 분석하여 연구대상 지반의 독자거동영역과 동일거동영역을 구분할 수 있었다. 이처럼 측점들 간의 상대적 침하거동을 분석을 통해 거동영역을 구분할 수 있다면, 주변지역의 융기, 지반파괴영역 예측, 터파기 공사 시 활동파괴의 방지 등 침하관리와 안정관리에 도움을 줄 수 있다고 판단된다.