Effect of oxidizing treatment on electrocatalytic activity of boron-doped amorphous carbon thin films

Wang Chen-Song,Suo Ni,Huang Hao,Wu Ai-min,Cao Guo-Zhong,Zhang Gui-Feng 한국탄소학회 2019 Carbon Letters Vol.29 No.5

Boron-doped amorphous carbon (BDAC) thin films with a regular oxygen reduction reaction (ORR) catalytic activity were synthesized in a hot filament chemical vapor deposition device using a mixture of CH4 and H2 as a gas source and B2O3 as a boron source and then oxidized in air at 380–470 °C for 15–75 min. Scanning electron microscope, transmission electron microscope, Raman spectroscopy, X-ray photoelectron spectroscopy, and electrochemical tests were used to characterize the physical and electrochemical properties of the BDAC catalysts. It was concluded that the BDAC catalyst oxidized at 450 °C for 45 min showed the best ORR catalytic activity in alkaline medium. The oxygen reduction potential and the transfer electron number n, respectively, are − 0.286 V versus Ag/AgCl and 3.24 from the rotating disk electrode experiments. The treated carbon film has better methanol resistance and stability than the commercial Pt/C catalyst.

Effect of oxidizing treatment on electrocatalytic activity of boron‑doped amorphous carbon thin films

Chen‑Song Wang,Ni Suo,Hao Huang,Ai‑min Wu,Guo‑Zhong Cao,Gui‑Feng Zhang 한국탄소학회 2019 Carbon Letters Vol.29 No.5

Boron-doped amorphous carbon (BDAC) thin films with a regular oxygen reduction reaction (ORR) catalytic activity were synthesized in a hot filament chemical vapor deposition device using a mixture of CH4 and H2 as a gas source and B2O3 as a boron source and then oxidized in air at 380–470 °C for 15–75 min. Scanning electron microscope, transmission electron microscope, Raman spectroscopy, X-ray photoelectron spectroscopy, and electrochemical tests were used to characterize the physical and electrochemical properties of the BDAC catalysts. It was concluded that the BDAC catalyst oxidized at 450 °C for 45 min showed the best ORR catalytic activity in alkaline medium. The oxygen reduction potential and the transfer electron number n, respectively, are − 0.286 V versus Ag/AgCl and 3.24 from the rotating disk electrode experiments. The treated carbon film has better methanol resistance and stability than the commercial Pt/C catalyst.

^161, ^163Dy의 0.003eV~50keV의 중성자 포획 단면적 측정

민영기,윤정란,노태익,김귀년,이삼열 東亞大學校附設基礎科學硏究所 2002 基礎科學硏究論文集 Vol.19 No.1

교토대학 원자로 연구소의 46MeV 전자선형가속기를 사용하여 중성자 TOF 방법으로, 에너지 영역 0.003eV∼50keV의 ^161, 163Dy sample의 중성자 포획 단면적을 측정하였다. 본 실험에서 사용된 Bi_4Ge_3O_12(BGO) 섬광 검출기는 sample의 핵반응에서 나오는 즉발 포획 감마선 측정에 사용하였다. 이 검출기는 중성자 선원으로부터 거리 12.7±0.02m 위치에 12개의 블록으로 되어 있으며, sample에 포획되는 중성자 flux의 절대치를 구하기 위해 Sm(n, γ) 및 ^10B(n, αγ) 반응을 이용하였다. ^161, 163Dy에 대한 포획 단면적 측정결과는 ENDF/B-VI 결과와 비교하였다. The neutron capture cross sections of ^161, 162Dy has been measured in the energy region from 0.003eV 50keV by using the neutron time-of-flight(TOF) promptγmethod with a 46MeV electron linear accelerator at the Research Reactor Institute, Kyoto University. An assemble of twelve pieces of BGO scintillation detectors, which was placed at a distance of 12.7±0.02mm from the neutron source, was employed as a total energy absorption detector for the prompt capture gamma-ray measurement, to obtain the absolute capture cross section value. The sample of ^161, 163Dy is a form of metallic plate. An enriched boron sample was employed to monitor the neutron flux/spectrum of the TOF beam using the standard reference cross section of the ^10B(n, αγ) reaction. Previous measurements and evaluated data in ENDF/B-VI was compared with the present results.

용융탄산염 연료전지의 CFD를 이용한 수치모사

劉旼炡,鄭貴榮 弘益大學校 科學技術硏究所 2004 科學技術硏究論文集 Vol.15 No.-

The gas channels of the molten carbonate fuel cell (MCFC) have been studied numerically. Distributions of pressure and gas compositions in the anode and the cathode gas channels were observed. The rate constant of the electrochemical reaction was deduced with the value of hydrogen usage. Calculations were made at the different values of the reaction rate constant and also at different sizes of gas channels. The commercial fluid dynamics program, Phoenics, was used. When the volumetric velocity is constant and the height of gas channel is changed, the changes of the CO2 concentration are big when the height of gas channel is thick. When the volumetric velocity is constant and the rates of generation and consumption are multiplied by 0.5, 1 and 2, the changes of the CO2 concentration are big when the rate of generation and consumption is big. On the other hand, when the linear velocity is constant, the changes of the CO2 concentration are big when the height of gas channel is thin.

위암 환자에서 절제된 림프절 수의 차이와 관련이 있는 인자

정귀애,박정희,변익건,김경종,장정환,김권천,민영돈 朝鮮大學校 附設 醫學硏究所 2004 The Medical Journal of Chosun University Vol.29 No.1

Purpose: By the definition of UICC TNM classification (fifth edition), the nodal stage of gastric cancer is based on the number of metastatic lymph nodes, which is influenced by the number of resected lymph nodes. And individual differences in the number of resected lymph nodes had been observed in patients with gastric cancer. The aim of this study is to verify the factors which are associated with the difference in the number of resected lymph nodes in patients with gastric cancer. Methods: We reviewed 613 patients with gastric cancer who underwent curative resection and D2 lymph node dissection with 15 or more resected lymph nodes. The number of resected lymph nodes was analyzed according to the characteristics of patients, the types of operation and prognostic factors of gastric cancer. Results: The mean number of resected lymph nodes per patient was 33.0 (median: 31.0, range: 15-88). The number of resected lymph nodes was significantly associated with the types of operation, the location and size of tumor, macroscopic types, depth of tumor invasion and the number of metastatic lymph nodes. Patient's age, gender and the histopathological finding's had no relationship with the number of resected lymph nodes. Conclusions: The number of resected lymph nodes from gastric cancer was different in each patient despite of same D2 lymph node dissection and it was associated with several prognostic factors of gastric cancer.

Android 기반의 PC 원격 제어기

박귀상;이나경;조혜민;양길웅;박세명 인제대학교 2012 仁濟論叢 Vol.27 No.1

One of the most attracting and interesting point of the application of the smart phone, particularly such as Android based smart phone, is not only providing additional useful functions to the user but also its easy and wide availability through the connection of the other types of devices. In this paper, we proposed and implemented Android application for the Remote PC control. In this paper, we used UDP network communication for sending data to the server and controlled the packet transmission rate to minimize the packet loss. And we used Spy++ tools and PostMessage function to controll outer device. We show that application based on the Android is very useful method for achieving and supporting the harmonized function between various independent devices

B_(2)O_(3)를 첨가한 Ni-Cu-Zn Ferrite의 자성에 대한 소결온도 효과

김민경,이명호,고재귀,송승기 명지대학교 자연과학연구소 2005 자연과학논문집 Vol.24 No.-

B_(2)O_(3)가 첨가된 Ni-Cu-Zn 페라이트의 소결온도 변화에 따른 자기적 성질을 연구하였다. 실험에 사용한 시료는 0.1 wt%의 B_(2)O_(3)를 (Ni_(0.204)Cu_(0.204)Zn_(0.612))Fe_(1.198)O_(2.98)에 첨가하여 각각 1000℃, 1100℃ 그리고 1200℃으로 4시간 동안 소결시켜 제작했다. 시료의 자기적 성질은 X-ray 회절 패턴, 자기이력 곡선, 초투자율, 손실계수 그리고 비저항을 측정하여 연구하였다. 자기이력 곡선과 초투자율 측정 결과로부터 세 시료 모두 우수한 연자성체가 되었음을 확인하였고, 소결온도가 높을수록 coercive force(H_(c))의 감소와 초투자율의 증가가 관찰되었다. 특히 가장 높은 온도(1200℃)로 소결한 시료의 Hc는 0.217Oe이었고, 초투자율은 전 영역의 주파수에 걸쳐 가장 큰 값을 유지하였다. 전력손실은 1 ㎑~10 ㎒ 주파수 영역의 교류에 대해 시료 모두 안정된 값을 갖고, 1200℃로 소결된 시료의 전력손실과 비저항은 시료 중 가장 적은 값을 가졌다. We have studied the dependence of B-doped Ni-Cu-Zn ferrite on sintering temperature. The samples were prepared from 0.1 wt% B_(2)O_(3)-doped (Ni_(0.204)Cu_(0.204)Zn_(0.612))Fe_(1.198)O_(2.98) ferrites and sintered at 1000℃, 1100℃ and 1200℃ for 4 hours respectively. The crystal structures of the samples were identified by X-ray diffraction pattern, and the magnetic properties of those were investigated by measuring X-ray diffraction pattern, hysteresis curve, initial permeability and resistivity. The results showed that all of the three samples were good soft magnetic materials, and initial permeability increased with the decreasing of Hc as the sintering temperature became higher. Especially, the sample sintered at 1200℃ showed Hc of 0.217Oe and maintained the highest value of initial permeability through the whole frequency range. The loss factors of the samples showed good frequency stability from 1 ㎑ to 10 ㎒ and both the loss factor and resistivity of the ssample sintered at 1200℃ was the least.

학습동기 향상 프로그램이 학습부진아의 학습태도에 미치는 효과

박귀자,민천식 대구교육대학교 초등교육연구소 2008 초등교육연구논총 Vol.23 No.2

본 연구는 학습동기 향상 프로그램이 학습부진아의 학습태도에 미치는 효과를 알아 보려는 단일대상 실험연구로써,다음과 같은 구체적인 연구 문제를 설정하였다. 첫째,학습동기 향상 프로그램이 학습부진아의 자신감에 미치는 효과는 어떠한가? 둘째,학습 동기 향상 프로그램이 학습부진아의 열의에 미치는 효과는 어떠한가? 셋째,학습동기 향상 프로그램이 학습부진아의 성공기대에 미치는 효과는 어떠한가? 이를 위하여,대구 광역시 S초등학교 6학년에 재학 중인 학습부진아 3명을 대상으로,매회 40분씩,주 2회,8주간,총 18회기 동안 실험하였으며,자료 처리는 사전 · 사후 학습태도 검사를 실시한 후 각각의 문항별 원점수 변화 추이를 Likert식 5단계 평정척도표로 비교 분석하였고,각 회기별로 나타난 대상 아동의 행동변화를 관찰 기록하여 이를 질적 분석하였다. This study is to find out the effect of program for heightening learning motive on learning attitude of children with underachieved in class as single subject experimental design, and the detailed dependent variables included the self-confidence, Passion, and expectation for success of those children. As for the subject of the study, 3 children with underachieved in learning, who are attending S elementary school in Daegu as six grade students. The experiment was conducted for the total of 18 times, twice a week for 9 weeks, and it took 40 minutes for one test every term. The training program which was used, was made by reorganizing the effect of program for heightening learning motive on learning attitude of children with underachieved by Kim Nam-0k(1991) suited to the school year of the subjects of the test. As for an assessment tool for finding out the changes in their learning attitude, only the contents of the sub-area of a learning activity test paper by Shim Jae-Sun(1996) and of a learning attitude test paper by Choi Sun(2004) were extracted according to my intention, and prior and post tests were conducted with the contents. And then, the trend of the changes was compared and analyzed with Likert 5 type rating measures, and this was expressed with a table and a bar graph by converting them into percentile. In addition, the changes in the attitude of the children were observed and recorded every term, and were subject to a qualitative analysis. The Conclusion attained from result of this study were as follows: First, the effect of program for heightening learning motive on learning attitude of children with underachieved is effective in heightening the self-confidence of children with underachieved in learning by making them realize that they have their own strength, and they can be good at studying. Second, the effect of program for heightening learning motive on learning attitude of children with underachieved is effective in heightening the passion of children with underachieved in learning by having them realize the reason why they need to study through activities of establishing short-to-long-term education goals for materializing their dream. Third, the effect of program for heightening learning motive on learning attitude of children with underachieved is effective in heightening the expectation for success of children with underachieved in learning by letting them have successful experience and success case by having them make their business card with a job that they dream to have, and creating the sense of expectation that they can achieve anything if they concentrate on something.

단위 연료전지 내 가스채널에서의 Phoenics를 이용한 수치모사 연구

劉旼炡,鄭貴榮 弘益大學校 科學技術硏究所 2005 科學技術硏究論文集 Vol.16 No.-

The mathematical modeling of MCFC was carried out to observe the effects of the water-gas shift reaction. Using the commercial CFD program Phoenics, studies on the butterfly-type fuel cell was carried out. Calculated results were compared with those of the general type fuel cell. In previous studies, it was assumed that properties of gases along the direction of gas channel height were constant. The consumption and the generation rates of CO_(2) could be decided as the rates which gave 0.4 of the hydrogen utilization in the anode gas channel. The y-directional average values were similar to the values near the separator surface and they positioned near the electrode surface. Therefore it was shown that it is safe to assume that the gas concentration along the direction of gas channel height is constant. Effects of the size of channel height on the x-directional distribution of X_(a)co_(2) appeared greater at a constant linear velocity rather than at a constant volumetric flow rate. As expected, the x-directional distributions of Xco_(2) in the butterfly type gas channels became more uniform.

첨가제가 Mn-Zn 페라이트의 자기적 성질에 미치는 효과

이명호,김민경,고재귀,송승기 명지대학교 자연과학연구소 2004 자연과학논문집 Vol.23 No.-

우리 연구는 첨가제가 페라이트에 미치는 효과를 연구하기 위해 두 종류의 서로 다른 금속이온을 첨가제로 한 Mn-Zn 페라이트 시료를 제작하여 이들의 자기적 성질을 비교 분석하였다. 시료 제작에 사용된 Mn-Zn 페라이트의 주 원료 조성비는 31 mol% MnO, 16 mol% ZnO 그리고 53 mol% Fe_(2)O_(3)이다. 볼밀 작업을 통해 주 원료를 잘 혼합한 후 950℃에서 3시간 동안 하소하였다. 하소된 재료에 실험에 필요한 첨가물을 혼합한 뒤 성형과정을 거쳐 1300℃에서 3시간 동안 소결하였다. 첨가물은 0.1 wt% Na_(2)SiO_(3)만을 사용한 경우 (Sample 1)와 0.05 wt% Na_(2)SiO_(3), 0.1 wt% CaO와 0.05 wt% Al_(2)O_(3)를 첨가한 (Sample 2) 두 종류의 첨가제를 이용하였다. 두 시료에 대한 자성 특성을 측정한 결과 Sample 2 시료가 Sample 1에 비해 포화자속밀도(saturation flux density) B_(8)는 더 커진 반면 잔류자속밀도(residual flux density) B_(1)과 보자력(coercive force) H_(6)는 더 적어졌음을 확인하였다. 또한 고주파 측정에서도 0.05 wt% Na_(2)SiO_(3), 0.1 wt% CaO와 0.05 wt% Al_(2)O_(3)가 첨가된 시료에서 주파수 증가에 따르는 자기손실이, 다른 시료에 비해, 매우 완만하게 증가하는 것을 관찰하였다. 이들 자기 측정으로부터 0.05 wt% Na_(2)SiO_(3), 0.1 wt% CaO와 0.05 wt% Al_(2)O_(3)의 첨가제가 Mn-Zn 페라이트의 연자성 특성을 향상시켯음을 확인하였고, 이 결과는 이들 첨가물이 소결(sintering)과정에 관하여 Mn-Zn 페라이트 미세구조의 치밀화와 입자성장을 촉진시키는 효과가 있음을 보인다. We prepared two kinds of Mn-Zn ferrites composed of 31 mol% MnO, 16 mol% ZnO and 53 mol% Fe_(2)O_(3) as a main material. These were well mixed in a ball-milling machine and calcinated at 950℃ for 3 hours. After being mixed with two kinds of additives of 0.1 wt% Na_(2)SiO_(3) (Sample 1) and 0.05 wt% Na_(2)SiO_(3), 0.1 wt% CaO and 0.05 wt% Al_(2)O_(3) (Sample 2) respectively, the materials were molded and sintered at 1300℃ for 3 hours. The sample 2 was found to have more saturation flux density, and less residual flux density and coercive force than the other one, which means that the sample 2 is more suitable for soft-magnetic material. When the samples were applied by AC magnetic field in the frequency range of 10 kMz~1 MHz, both have shown relatively stable initial permeabilities up to 1 MHz. On the other hand, the loss factof of sample 2 became less than that of sample 1 in the high frequency range above 100 kHz although there was no much difference in the resistivity of both samples through the frequency change, which suggests the additives in the sample 2 has suppressed the viscosity loss in the high frequency range. We conclude that the 0.05 wt% Na_(2)SiO_(3), 0.1 wt% CaO and 0.05 wt% Al_(2)O_(3) additives has promoted coarsening and densification of the microstructure of the Mn-Zn ferrite and resulted in the better quality of the Mn-Zn ferrite