• 공학교육연구
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• 제16권4호
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• pp.30-36
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• 2013

Applying intuitive learning method on engineering education, especially for the mechanical engineering, is hardly found from the previous case studies and is not easily proved its beneficial verification. Verbal repetition is also rarely used to investigate its positive effects on educational methodology for both science and engineering disciplines. To prove the education effects of these two methods; we used intuitive thinking time period at the beginning of each lecture and let students repeat the concepts and the equations verbally. These two methods were related to the subjects of each lecture, and were used for students to try to draw engineering thinking from natural phenomena that they could easily experience in daily life. The methods could help them to memorize theoretical ideas. We investigated the effects of intuition and verbal repetition methods by comparing the scores of final exam with those of midterm exam. The results revealed significant improvement; 77.6% of the students achieved higher score in their final exam compared to midterm exam. We plan to investigate qualitative contributions of intuition and verbal repetition methods to the students' achievement for the further research.

• 대한화장품학회지
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• 제24권3호
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• pp.59-64
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• 1998

In order to lower porosity of the porous silica, titanium alkoxide solution was filled in the pore of silica in the heating-vacuum condition. The specific surface area of modified samples was decreased effectively from 900 m$^2$/g to 100 m$^2$/g. (The aggregation phenomena in modified samples were improved fairly.) Samples were heated at 600 , and then the titanium alkoxide in the pore was decomposed completely to titanium oxide from TGA-DTA measurement. From SEM result, it was evident that titanium oxide did not coat the surface of the silica. The modified samples were analyzed using SEM, DTA-TGA, BET, and UV-visible spectrometer.

• 한국CDE학회논문집
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• 제19권3호
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• pp.245-252
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• 2014

Engineering applications of global optimization techniques are recently abundant in the literature and it may be caused by both new methodologies arising and faster computers coming out. Many of the optimization techniques are based on natural or biological phenomena. This study put focus on enhancing the performace of Cuckoo Search (CS) among them since it has the least number of parameters to tune. The proposed enhancement can be achieved by applying surrogate-based optimization at every cycle of CS, which fortifies the exploitation capability of the original method. The enhanced algorithm has been applied several engineering design problems with constraints. The proposed method shows comparable or superior performance to the original method.

• Animal cells and systems
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• 제10권2호
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• pp.79-83
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• 2006

Tissue plasminogen activator (tPA) is used to lyse clots and reperfuse brain in ischemic stroke. However, sideeffects of intracerebral hemorrhage (ICH) and edema limit their clinical application. In part, these phenomena has been linked with elevations in matrix metalloproteinase-9 (MMP-9) in neurovascular unit. However little is known about their regulatory signaling pathways in brain cells. Here, I examine the role of MAP kinase pathways in tPA-induced MMP-9 regulation in rat cortical astrocytes. tPA $(1-10\;{\mu}g/ml)$ induced dose-dependent elevations in MMP-9 and MMP-2 in conditioned media. Although tPA increased phosphorylation in two MAP kinases (ERK, JNK), only inhibition of the JNK pathway by the JNK inhibitor SP600126 significantly reduced MMP-9 upregulation. Neither ERK inhibition with U0126 nor p38 inhibition with SB203580 had any significant effects. Taken together, these results suggest that c-jun N-terminal kinase (JNK) plays an essential role for tPA-induced MMP-9 upregulation.

• 대한기계학회논문집A
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• 제27권1호
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• pp.48-57
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• 2003

This study presents nonlinear vibration of a cantilever beam subjected to electromagnetic forces. The dynamic responses of the beam show various nonlinear phenomena with the variation of the system parameters, such as the jump phenomenon, multiple solutions, and the movement of the natural frequency. In this study the nonlinear stiffness due to electromagnetic forces which depends on air gap size is measured experimentally, and the system is modeled by a single degree of freedom nonlinear dynamic system and solutions are solved numerically. The numerical results show good agreements with the experimental results, which demonstrate the nonlinearity of electromagnetic force. Finally the occurrences of the jump phenomenon and the first, second and fourth harmonic components are confirmed in using the method of multiple scales.

• 한국초등과학교육학회지:초등과학교육
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• 제18권2호
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• pp.131-144
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• 1999

This study investigates the pre-service teacher trainees' reactions to and evaluations about the earth science teaching method that utilizes songs. The subjects of the study were 81 university students in teacher training institutes for primary schools and secondary schools. The researcher used songs which the subjects judged to be reflecting some of the natural phenomena related to the earth science. The teacher trainees were taught some of the earth science concepts with the help of the selected songs. Discussions about the possibilities of the songs as an ai d to science teaching were also encouraged. The teacher trainees demonstrated positive reactions to the teaching method, and expressed their intention to use songs in their future teaching. The method also inspired the trainees to be inquisitive in their everyday life and seek other effective teaching methods.

• 대한공간정보학회지
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• 제24권2호
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• pp.95-106
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• 2016

Landslide is one of the natural hazards, triggered by rainfall or earthquake and it leads to damage and loss of properties and lives especially in hilly and mountainous regions. Inventory maps of the area is of much importance in order to understand the landslide phenomena in detail, conduct further studies on landslide, prepare susceptibility map and minimize risk. Inventory maps of landslides can be constructed by several methods, using multiple images through visual interpretation, using algorithms in multi-spectral or SAR images or verification from field investigation. The possible methods were explored for Sindhupalchowk district of Nepal, which was struck by massive earthquake on 2015 and landslide inventory was prepared. The inventory was analyzed for its frequency over elevation, slope aspect and dominant soil classes and also the information value for their occurrence probability.

• 설비공학논문집
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• 제13권9호
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• pp.845-852
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• 2001

The phenomena of energy separation in vortex tubes was investigated experimentally to see the effects of the conductivity of a tube and convective heat transfer on the outer surface of a tube. The experiment was carried out with different conductivity (pyrex, stainless steel and copper) of a tube and three kinds of convective heat transfer modes (adiabatic condition, natural convection (air) and forced convection (water) on the outer surface of a tube. the results were obtained that hot exit fluid temperature was highly affected by a change of conductivity of a tube when the outer surface was cooled by the forced convection of water. However, the cold exit temperature was little affected by heat transfer modes on the outer surface in vortex tubes.

• 통합자연과학논문집
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• 제13권1호
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• pp.1-7
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• 2020

This paper proposes a novel fractional frequency reuse(FFR) based on dynamic user distribution. In the FFR, a macro cell is divided into two regions, i.e., the inner region(IR) and outer region(OR). The criterion for dividing the IR and OR is the distance ratio of the radius. However, these distance-based criteria are uncertain in measuring user performance. This is because there are various attenuation phenomena such as shadowing and wall penetration as well as path loss. Therefore, we propose a novel FFR based on dynamic user classification with signal to interference plus noise ratio(SINR) of macro users and classify the FFR into two regions newly. Simulation results show that the proposed scheme has better performance than the conventional FFR in terms of SINR and throughput of macro cell users.

• 한국환경과학회지
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• 제25권10호
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• pp.1389-1396
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• 2016

A monitoring system for a field magnetometer was configured with assistance of a Raspberry Pi as a data logger. The suggested geomagnetic system uses a semi-real-time data transmission module. The system consists of two parts: a field-observation part and a data-center part. The field-observation part comprises a Raspberry Pi, magnetometer, LTE router, and power source, while the data center part takes samples at the site. The collected magnetometer data are then sent to the data center through the LTE router. The newly designed monitoring system was deployed and checked in Jeju-do island, and found to operate stably. The suggested system is promising in that it is simple and cost saving, providing at least physical insight and knowledge on the complex natural phenomena.