중위권 공과대학에서 학생 과제물 수행에 대한 문제점 분석

백현덕,박진원 한국공학교육학회 2009 공학교육연구 Vol.12 No.3

This paper is on the analysis of the present situation in carrying out homework assignments of the students in the college of Science and Technology, Hongik University. Our survey confirmed that the purpose of the assignments was not satisfactorily achieved, because only a few students solve the problems by their own efforts and most of the other students just copied their peers' work. The reason for this problem was analysed based on the result of questionnaire for the professors and students. Possible solutions for the problem is proposed, such as providing sufficient number of teaching assistants and changing instruction strategy, reflecting the significance of homework assignments in the learning process. As one of the probable solutions, a team-based assignment is proposed, and expected and observed positive results were discussed. 본 논문은 홍익대학교 과학기술대학 재학생들의 과제물 수행에 대한 실태를 조사 분석하여 문제점에 대한 개선방안을 찾기 위한 것이다. 조사된 과제 수행의 문제점은 예상한 바와 같이 소수의 학생들만이 문제를 풀고 대부분 학생들은 동료들이 푼 것을 베껴서 제출하고 있다는 점이었다. 교수 및 학생들을 대상으로 실시한 설문조사 결과 그 원인은 학생들의 면학분위기가 조성되지 못함, 과제물이 학생들의 수준에 비해 너무 어려움, 학생들의 과제 수행을 도와 주는 제도적 장치의 미비 등으로 나타났다.해결 방안으로 제시될 수 있는 것은, 첫째 장학생 제도의 운영방법을 개선하여 자격을 갖춘 과목 조교를 충분히 확보하는 것이다. 둘째 교수들은 과제물 운영이 정상적으로 이루어질 수 있도록 더 적극적인 해결책을 찾는 것이다. 학습 효과 달성을 위해서 익히는 과정의 중요성을 교수방법에 반영할 필요가 있는 것이다. 셋째 팀 단위 학습법을 과제물 운영에 적용하는 방안을 생각할 수 있다. 공동 작업으로 인한 과제물에 대한 심리적, 시간적 부담 경감, 모여서 문제를 해결하는 과정을 통한 면학분위기의 조성 및 팀워크 능력 배양, 교수의 과제물 평가와 피드백의 용이 등 이점이 확인되고 있다.

기전력측정법에 의한 SrBi₂O₄의 생성자유에너지

白鉉德 홍익대학교 산업기술연구소 1994 産業技術 Vol.4 No.-

The free energy of formation of SrBi_2O_4 from its constituent oxides was determined at 630℃. The activity values of Bi_2O_3 and SrO were measured by the electrochemical e.m.f measurement method and free energy of formation was obtained to be -65.7kJ/mol by the relevant thermodynamic relation.

Ce_(1-x)Ca_(x)O_(2-δ) (x=1/6)에서의 프로톤 전도도

白鉉德 弘益大學校 産業技術硏究所 2004 産業技術 Vol.14 No.-

Electrical conductivity of sintered Ce_(1-x)Ca_(x)O_(2-δ) (x=1/6) was measured at temperatures 750, 800 and 850℃ in dry and wet air. No measurable conductivity increase was observed in wet atmosphere, as expected in usual proton-conducting oxides such as BaCeO₃, and thus it was concluded that no proton conduction occurs in this oxide due to the water absorption.

Y₂O₃가 도핑된 SrZrO₃-금속전극계의 전기전도 특성

백현덕,이풍헌,Baek, Hyun-Deok,Lee, Poong-Hun 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.4

Electrical conduction in $SrZr_{1-x}Y_xO_{3-\delta}$((x=0.05, 0.10)-metal electrode system was investigated by impedance spectroscopy and two-probe d.c. conductivity measurement. Electrode conductivity in anodic direction varies with $P_W^{1/2}$( and that in cathodic direction with $P_{O2}^{1/4}$ in oxidizing atmosphere. In hydrogen atmosphere, the addition of water vapor increased the electrode conductivity both in anodic and cathodic direction. Increasing dopant concentration from 5 to 10% showed a more than four times increase in anodic conduction as well as bulk conduction of the solid electrolyte. This observation implies that unfilled oxygen vacancy concentration increases rapidly as the dopant content increases in humid atmosphere. The activation energy of cathodic conduction in Pt and Ag electrode was nearly same below $800^{\circ}C$ which means the rate of cathodic reaction is determined by the reaction in the electrolyte surface rather than on the metal electrodes. $SrZr_{1-x}Y_xO_{3-\delta}$(x=0.05, 0.10)-금속전극 계에서 임피던스법과 d.c.법으로 전기전도도를 측정함으로써 고체전해질 및 전극전도도를 고찰하였다. 고체전해질과 anode를 통한 전기전도도는 $P_W^{1/2}$(PW는 수증기분압)에 의존하여 증가함을 보였다. Cathode 전도도는 $P_{O2}^{1/4}$에 비례함을 보였으며, 수증기분압 증가와 함께 감소하여 고체전해질내의 전자 결함의 농도와 함께 증가하는 것을 알 수 있었다. 수소분위기에서는 수증기의 첨가가 anode와 cathode 두 방향의 전극반응 속도 모두를 촉진하였다. 도펀트 첨가량이 5%에서 10%로 증가될 때 anode와 고체전해질의 전기전도도가 3배 이상 크게 증가하여 유효 산소이온공공의 농도가 급격히 증가함을 알 수 있었다. Pt와 Ag전극을 통한 cathode 전도도의 활성화에너지가 거의 같은 값을 나타냈으며 이는 cathode반응의 속도가 금속전극이 아니라 고체전해질표면에서 일어나는 반응에 의하여 결정되는 것으로 해석되었다.

공학교육에서의 팀성취분담 협동학습 모형(STAD)의 적용과 효과

백현덕(Hyun-Deok Baek),박진원(Jin-Won Park) 한국공학교육학회 2012 공학교육연구 Vol.15 No.6

Problem solving by homework assignment is a process of practicing what were discussed in classrooms and thus is considered as an essential part of learning procedure in engineering education. We introduced the concept of cooperative learning, Student Teams-Achievement Division(STAD), to improve the students’ learning efficiency by in-class problem solving. The instructor explained fundamental concepts, and lecture materials were handed out to compensate for the time of in-class team activity. Brief tests were given after every chapter, and team-based additional credits were given for the improvement comparing the average of previous tests of each student. This attempt of modified STAD was evaluated to have brought about a significant improvement in students academic achievement, in addition to activating classroom atmosphere.

산화물 내에서의 산소의 화학 확산계수

白鉉德 弘益大學校 産業技術硏究所 2007 産業技術 Vol.17 No.-

In the chemical diffusion of oxygen, given by ◁수식 삽입▷(원문을 참조하세요) the effect of the thermodynamic factors, Wc' and WVo' was studied. As the concentration of the charge carriers, oxygen vacancies or electrons, increases, the corresponding thermodynamic factor, Wv_(o') or Wv_(e'), is expected to decrease, and thus the contribution of the charge carrier whose concentration is larger than the other becomes smaller. In case the concentartion of electron increases, the effect of transport number being considered together in the given equation of ◁수식 삽입▷(원문을 참조하세요) above, the values of ◁수식 삽입▷(원문을 참조하세요) and ◁수식 삽입▷(원문을 참조하세요) reduce and that of ◁수식 삽입▷(원문을 참조하세요) become more significant. Analogously an enhanced concentration of oxygen vacancies will give rise to reductions of ◁수식 삽입▷(원문을 참조하세요) and ◁수식 삽입▷(원문을 참조하세요) and an increase in ◁수식 삽입▷(원문을 참조하세요). As a result, obviously it is shown that the chemical diffusion coefficient is controlled by the diffusion coefficient of charged species of a lower concentration.

Y₂O₃가 도핑된 BaThO₃에서의 전기전도특성

白鉉德 홍익대학교 산업기술연구소 1998 産業技術 Vol.8 No.-

Electrical conduction of BaTh_0.9Y_0.1O_2.96 ceramics was investigated at 1276K. Total and partial conductivities were modeled using a method previously reported by the present author. The parameters used were derived based on the work of Tsuji and coworkers. Calculated conductivities showed a good agreement with the experimental results. The electrical conduction was dominated by holes in dry air and gradually dominated by protons with an increasing water pressure.

고온 프로톤전도체의 수소 분위기 하에서의 전기전도 특성

白鉉德 홍익대학교 산업기술연구소 2000 産業技術 Vol.10 No.-

Electronic conductivity was predicted for high-temperature proton-conductors based on their defect structure in the condition ionic defects are dominent over electronic ones. Electronic conductivity was expressed as a function of vapor pressures of oxygen and water vapor, not explicitly of hydrogen vapor pressure. Dissolution of water into the crystals of HTPCs bring about an increase in electronic conduction as well as proton conduction, and total conductivity was expected to show a rapid increase with an increasing water vapor pressure.

Y-도핑된 SrZrO_3 - 금속전극계의 전기전도 특성

白鉉德 홍익대학교 산업기술연구소 2001 産業技術 Vol.11 No.-

Electrical conduction in SrZr_xY_1-xO_3-δ(x= 0.05, 0.10)-metal electrode system was investigated by impedance spectroscopy and two-probe d.c. conductivity measurement. In 10%-doped samples, electrode conductivity in anodic direction varies with P_w^1/2 and that in cathodic direction with P_o2^1/4 in oxidizing atmosphere. In hydrogen atmosphere, the addition of water vapor increased the electrode conductivity both in anodic and cathodic direction. Increasing dopant concentration from 5 to 10% showed more than four times increase in anodic conduction as well as bulk conductivity of the solid electrolyte. This observation may be due the fact that the effective oxygen vacancy concentration is not proportional to the apparent dopant content. The activation energy of d.c. conductivity in Pt and Ag electrode was nearly same, which means the rate of cathodic reaction is determined by the reaction in the electrolyte surface rather than on the metal electrodes.

산소 이온 전도체의 열역학적 안정성 제고

白鉉德 홍익대학교 산업기술연구소 1993 産業技術 Vol.2 No.-

The stability of Bi_2O_3 against reduction was investigated in the bismuth sesquioxide and alkaline earth oxide binary system. Using cells with alkaline earth fluoride as the solid electrolyte, the activity of CaO, SrO and BaO was measured. Then using Gibbs-Duhem integration, the activities of Bi_2O_3 were determined. In the high-ionic-conductive rhombohedral phase region, the activity of Bi_2O_3 decreased substantially in all three systems and showed negative deviation from Raoult's Law. The rhombohedral phase in the Bi_2O_3-SrO system showed the lowest activity of Bi_2O_3, 0.117 in the SrO-richest composition, (Bi_2O_3)_0.57(SrO)_0.43 at 630℃.