• 대한화학회지
• /
• 제56권1호
• /
• pp.137-143
• /
• 2012

화학을 배우고 가르칠 때의 어려움을 파악하기 위하여, 화학교육 홈페이지 인터넷 화학 Q&A 게시판에 학생과 교사가 올린 질문을 분석하였다. 학생과 교사의 질문은 내용과 동기 측면에서 서로 다른 경향을 보였다. 화학I에서 학생들은 '물' 영역에 가장 많은 질문을 하였고 교사는 '생활 속의 화합물' 영역에 가장 많은 질문을 하였다. 화학II에서 학생들은 '기체, 액체, 고체'에, 교사는 '화학 반응과 에너지'가 가장 많은 질문을 하였다. 화학 관련 질문을 하는 동기로 학생들은 불분명한 화학 개념과 문제 해결에 도움을 받기를 원하였고, 교사는 정보 탐색이나 실험에 관련된 질문을 많이 하였다. 화학 Q&A 게시판은 화학을 배우고 가르칠 때 필요한 정보를 주고받는 장이 되고 있었다. 화학 교육에 Q&A 게시판을 활용하는 시사점을 논의하였다.

• 한국수소및신에너지학회논문집
• /
• 제15권4호
• /
• pp.274-282
• /
• 2004

This study focused on the development of high performance catalyst for autothermal reforming (ATR) of gasoline to produce hydrogen. The ATR was carried out over MgO/Al2O3 supported metal catalysts prepared under various experimental conditions. The catalysts before and after reaction were characterized by N2-physisorption, CO-chemisorption, SEM and XRD. The performance of supported multi-metal catalysts were better than that of supported mono-metal catalysts. Especially, it was observed that the conversion of iso-octane over prepared Ni/Fe/MgO/Al2O3 catalyst was 99.9 % comparable with commercial catalyst (ICI) and the selectivity of hydrogen over the prepared catalyst was 65% higher than ICI catalyst. Furthermore, it was identified that the sulfur tolerance of prepared catalyst was much better than ICI catalyst based on the ATR reaction of iso-octane containing sulfur of 100 ppm. Therefore, Ni/Fe/MgO/Al2O3 catalyst can be applied for a fuel reformer, hydrogen station and on-board reformer in furl cell powered vehicles.

• ETRI Journal
• /
• 제33권1호
• /
• pp.121-124
• /
• 2011

Digital harmonics, which may reduce the radio frequency sensitivity of a system, can be coupled with an antenna in a mobile handset. This letter presents a decoupling method for increasing the isolation between digital harmonics on a flexible printed circuit board (FPCB) and an antenna in terms of the ground mode current and the concept of reaction. We model the signal and ground lines in an FPCB as a loop circuit exciting a ground mode current and demonstrate a simple but efficient decoupling method for reducing the excited ground mode current.

• The Journal of Korean Physical Therapy
• /
• 제5권1호
• /
• pp.61-69
• /
• 1993

It was performed to encourage for Physical Therapist to apply the theory of center of the human body and segments in clinical situations. This study was investigated literarily on center of the human body and segments. Methods which search for the center-2 types, that is, method using reaction broad and segmental method-was suggested. The center location difference of gravity in human body depends on individual character. Generally, the center location is in kent of 2nd sacrum, that is, at $55\%$ of height from foot. The center of each segment is on 'link'. In the first place we must how the weight of segment we can search for the center easily. Mean segment coater location of extremities is at $42.33\%$ from each proximal end, and mean center of head and trunk lies at $45\%$.

• 제어로봇시스템학회논문지
• /
• 제12권5호
• /
• pp.419-424
• /
• 2006

In this study, a thermal control system which applied a Peltier device for the polymerase chain reaction(PCR) machine is to be designed. Here in order for it to easily follow the characteristics of the thermal cycle existing for gene amplification of the PCR sample, a PCR control board utilizing a thermal sensor, a Peltier, and a 8 bit microprocessor is made up. Especially a fuzzy type PD control algorithm is applied periodically in time response, and control system is implemented. For that matter, the characteristic data of subject system is obtained and analysed to begin with. Based on this analysed data, the proposed control algorithm is applied and an evaluation of the performance of the whole system take place through the PC.

• 한국표면공학회지
• /
• 제32권3호
• /
• pp.336-339
• /
• 1999

Photo-excited $TiO_2$ surface has a strong ability to induce various chemical reactions. Our study concentrates mainly on the utilisation of light energy to induce reactive radicals for environmental protection application. For instance, we have successfully used TiO$_2$ to break down foul smelling substances in air. In order to retain and separate the $TiO_2$ catalyst from the reactants and products, $TiO_2$ was immobilised by fixing onto various substrates. $TiO_2$ catalyst coated onto glass, wall paper and painted panel was found to show significant deodorising effect. The deodorising effect continues as long as$TiO_2$ is exposed to light irradiation.

• 자원리싸이클링
• /
• 제26권4호
• /
• pp.95-100
• /
• 2017

본 연구에서는 폐 PCB(printed circuit board) 표면을 긁어내어 회수한 구리분말을 용융하는 과정에서 용융온도 저감과 정제를 위하여 플럭스로 $Fe_2O_3$를 첨가하였으며, $Fe_2O_3$ 첨가량 및 온도에 따른 구리의 회수율과 불순물 농도에 미치는 영향을 조사하였다. 구리 회수율은 반응온도와 $Fe_2O_3$의 첨가비율이 증가할 수 록 증가하였다. 그리고 구리 중 산소, 실리콘, 철의 농도는 $Fe_2O_3$ 첨가량이 증가할수록 감소하였다. $Fe_2O_3$를 첨가하여 반응시킨 후의 슬래그를 XRD로 분석하여 fayalite($2FeO{\cdot}SiO_2$)와 철산화물을 확인하였다. 따라서 fayalite 슬래그의 생성에 의한 슬래그의 융점과 점도 감소가 구리 회수율의 증가에 크게 기여한 것으로 생각된다.

• 반도체디스플레이기술학회지
• /
• 제18권1호
• /
• pp.15-20
• /
• 2019

Inspection and measurement of surface quality is one of the most critical processes for manufacturing products such as semiconductor wafers, sapphire substrates, and display panels. The vibrations of the inspection and measurement devices are supposed to be the most dominant factors for severe measurement errors and longer measuring time. In this study, dynamic characteristics of an inspection and measurement device are analyzed through frequency response experiment and computer simulation to obtain parameters such as frequencies, magnitudes, mode shapes, and periods of vibrations. And then an active damper which consists of sensor, interface board, and actuator is designed based on the parameters to formulate the most effective reaction signal to suppress the vibrations which is generated by an interface board, and provided by an actuator. If the vibrations are measured by the sensor, the active damper immediately generates and provides the corresponding reaction signal to inspection and measurement device. The result shows that the active damper can suppress structural vibrations effectively and reduce measuring time of the device and enhance the productivity.

• 한국생산제조학회지
• /
• 제23권3호
• /
• pp.237-242
• /
• 2014

Recently much research are has been done into the compositions of lead-free solders. As a result, there has been a rapid increase in the number of new compositions. In the past, the properties of these new compositions were determined and verified through drop-impact tests. However, these drop tests were expensive and it took a long time to obtain a result. The main goal of this study was to establish an analytical method capable of predicting the impact life-time of a new solder composition for board-level flip chips though the application of drop simulations using LS-DYNA. Based on the reaction load obtain with LS-DYNA, the drop-impact fracture cycles were predicted. The study was performed using a Sn-3.0Ag-0.5Cu solder (305 composition). To verify the reliability of the proposed analytical method, the results of the drop-impact tests and life-time analysis were compared, and were found to be in good agreement. Thus, the new analytical method was shown to be very useful and effective.

• Journal of Advanced Marine Engineering and Technology
• /
• 제27권7호
• /
• pp.832-838
• /
• 2003

IMO NOx levels are generally possible to meet by means of primary on-engine measures. Nevertheless further significant follow-on reductions are likely to require a secondary after-treatment technique. SCR system is currently the only available technology proven at full scale to meet the 90% NOx reduction levels. Accordingly, maybe the use of an SCR system on board ship provides the solution to minimize this primary pollutant without increasing fuel consumption. In order to develop a practical SCR system for marine application on board ship, a primary SCR system using urea was made. The SCR system was set up on the ship. employed a two-stroke diesel engine as a main propulsion. which is a training ship in KMU (Korea Maritime Univ.). The purpose of this paper is to report the results about the basic effects of the above system parameters which is investigated from practical application through its trial use. The degree of NOx removal depends on some parameters. such as the amount of urea solution added, space velocity. reaction gas temperature and activity of catalyst. The preliminary results from trial run are presented.