• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.301-307
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• 2023

Deep learning requires building a deep neural network, collecting a large amount of training data, and then training the built neural network for a long time. If training does not proceed properly or overfitting occurs, training will fail. When using deep learning tools that have been developed so far, it takes a lot of time to collect training data and learn. However, due to the rapid advent of the mobile environment and the increase in sensor data, the demand for real-time deep learning technology that can dramatically reduce the time required for neural network learning is rapidly increasing. In this study, a real-time deep learning system was implemented using an Arduino system equipped with a fine dust sensor. In the implemented system, fine dust data is measured every 30 seconds, and when up to 120 are accumulated, learning is performed using the previously accumulated data and the newly accumulated data as a dataset. The neural network for learning was composed of one input layer, one hidden layer, and one output. To evaluate the performance of the implemented system, learning time and root mean square error (RMSE) were measured. As a result of the experiment, the average learning error was 0.04053796, and the average learning time of one epoch was about 3,447 seconds.

• Korean Journal of Environment and Ecology
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• v.19 no.3
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• pp.279-286
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• 2005

This study was conducted to analyze the changing pattern of the bird community after the construction of artificial wetland at Sihwah lake from may 2000 to January 2002. Total seventy seven bird species were recorded at Sihwa artificial wetland area during the survey. Number of the bird species and individuals were increased in second year than first survey year. Especially shorebirds and raptors were more increased than other groups. Long-term and continuous monitoring of bird community would be needed to clarify the reasons of increasing pattern of bird species and individuals in artificial wetlands of Sihwa lake. Until now, this area has been considered as suitable habitat for dabbling ducks than shore birds and has simple habitat environment consisting of open water surface and reed beds. Therefore, we suggest the follows for creation of diverse habitat types: 1) seasonal water-level manipulation 2) management of diverse aquatic plants and 3) creation of diverse land cover; sandy fields, gravelly fields, grasslands, etc.

• Journal of Korean Society of Forest Science
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• v.101 no.3
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• pp.480-487
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• 2012

This study was conducted to search the effects of debris barrier on the benthic macroinvertebrate. Gimcheon was selected as the survey site as it has relatively stable ecosystem with constantly running water. The survey was conducted 6 times before and after the construction of debris barrier from February in 2009 to October in 2010. In the first survey before construction, the identified species were 36 species belonged to 22 families, 9 order, 4 class, and 4 phylum. The figure slightly decreased to 30 species belonged to 18 families, 7 order, 2 class, and 2 phylum in the sixth survey after construction. Before construction, occupation ratio of EPT taxa was showed in the following order: Ephemeroptera (50.0%, 85.0%), Trichoptera (35.3%, 10.0%), and Plecopteran (14.8%, 5.0%). After construction, it was showed in the following order: Trichoptera (50.3%, 68.0%), Ephemeroptera (42.1%, 29.4%), and Plecopteran (7.5%, 2.7%). Ephemeroptera was the highest before construction. Trichoptera increased rapidly after construction. The Diversity, Richness, Evenness, and Dominance indices were all turned low in the second survey right after the construction. However, each index tended to increase with the course of time. In Functional Feeding Groups, GC type was the highest of 60.7% before construction. After construction, SC(53.1%) and FC(35.4%) increased rapidly and they became stabilized since the third survey. The result of this study reveals that debris barrier greatly affects the Aquatic Ecosystem right after its construction, but the system becomes stable and returns to normal with the course of time (about 18 months). Therefore, the study considering various influence factors such as time is required to recover completely through further long-term monitoring.

• The Korean Journal of Ecology
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• v.28 no.1
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• pp.45-53
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• 2005

Urban stream is an important place supporting urban ecosystem. This study was carried out to clarify the role of Jungrangchun for wintering waterbirds in Seoul. We monitored the fluctuation of waterbirds population using our census data (1997/98 winter) and pervious census data (the Ministry of Environment and National Institute of Environmental Research $1999{\sim}2004$). Wintering behaviours of common teals (Anas crecca) were also observed to understand the habitat use of waterbirds in this area. As a result of this, Jungrangchun was an important place to support $3,004\sim8,237$ wintering birds, mainly dabbling ducks and diving ducks. The population of diving ducks showed high annual fluctuation whilst the population of dabbling ducks regularly used this area every year The maximum number of waterbirds foraged and rested in late January and late February. In daily use, the number of waterbirds increased on afternoon and rapidly increased after sunset. It is assumed that waterbirds used this area not only as a nocturnal feeding site but also daytime feeding site. Thus, this result suggest that Jungrangchun is important for not only the daily use but also the nocturnal use of wintering waterbirds. The number of diving ducks was increased with low temperature and high wind speed. Therefore, this area was also a shelter of diving ducks on chilly and windy day.

• The Journal of the Korea Contents Association
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• v.22 no.5
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• pp.620-632
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• 2022

In order to prepare for the Anthropocene, this study aims to provide basic data on the direction of the Anthropocene liberal arts education by sharing experiences on anthropocene perception for undergraduates using the FGI analysis method. Interviews were conducted on 14 people who participated in liberal arts tutoring for about four months from October 2021 to January 2022, and as a result of confirming meaningful concepts according to qualitative analysis methods, a total of three topics, eight subcategories, and 16 sub-units were derived. "The advent of the new geological age" recognized that the anthrop tax was close to our lives, and it was time to predict the future through the meaning, seriousness, and development potential of the anthrop tax, and "Anthropocene Reorganization and Responsibility" emphasized the reorganization and responsibility of individuals, companies, and governments. The Direction of Human Tax Liberal Education proposed future basic liberal arts education, action practice for climate change, measures to overcome the anthropology using ICT technology, and various liberal arts education contents for a positive anthropology. In this regard, this study raised perception of the survival of mankind by in-depth exploration of the anthropocene in terms of liberal arts education, suggested the direction of future liberal arts education necessary in the anthropocene era, and suggested implications for the educational content and method.

• Korean Journal of Environment and Ecology
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• v.31 no.2
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• pp.127-134
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• 2017

This study was conducted to identify the reproductive behavior of the barn swallow. The study was carried out in Gwangju, Korea during the 2013 breeding season. In the morning, the nest-building frequency was 14.2~31.0 trips/h (10.2~19.8 trips/h by male and 4.0~11.4 trips/h by female). The nest-building activity took 7.6~15.9 min/h (4.8~8.1 min/h by male and 2.8~8.0 min/h by female). The nest-building time by female ($40.0{\pm}27.9sec/trip$) was about 1.5 times longer than the nest-building time by male ($26.1{\pm}15.5sec/trip$). Only the female incubated the eggs. The Incubation time was $50.6{\pm}17.5min/h$ (84%) at 6h, 24.5 min/h (40.8%) at 7h and 15.6 min/h (26.0%) thereafter. During daytime, the female incubation time showed a highly significant difference (p<0.001), and the incubation time at 6h was higher than that at other times. There was a significantly negative correlation between female incubation time and the mean air temperature(p<0.05). The frequency of feeding was $385.2{\pm}66.9trips/nest$ in the daytime ($219.2{\pm}37.1trips/nest$ by male and $166.0{\pm}30.8trips/nest$ by female). The frequency of feeding per hour was $32.1{\pm}12.3trips/h$ ($18.3{\pm}7.8trips/h$ by male and $14.3{\pm}4.5trips/h$ by female). The frequency of feeding per hour showed a significant difference in the range of 10h(p<0.05) and 15h(p<0.01) by sex. The time of feeding by female ($40.9{\pm}83.3sec/trip$) was longer than the time of feeding by male ($12.3{\pm}31.0sec/trip$). The juvenile defecation frequency was $45.6{\pm}8.4times/nest$ per day and showed a positive correlation with feeding frequency (p<0.05). The results of this study will be helpful in understanding the reproductive behaviors of the swallow adapted to the environment in Korea.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.306-306
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• 2008

기계적 에너지를 전기적 에너지로 변환하는 에너지 변환소자인 압전 세라믹스는 액추에이터, 변압기, 초음파모터, 초음파 소자 및 각종 센서로 응용되고 있으며, 그 응용분야는 크게 증가하고 있다. 최근에는 이러한 압전 소자를 앞으로 도래하는 ubiquitous, 무선 모바일 시대의 휴대용 전자제품, robotics, MEMS 분야 등의 대체 에너지원으로 응용하기 위한 연구가 진행되고 있다. 특히 인간의 걷기 운동 등과 같은 일상적인 동작으로 필요한 전력을 얻을 수 있고, 세라믹 소자를 이용하기 때문에 전자노이즈가 발생되지 않을 뿐 아니라 반영구적으로 사용할 수 가 있어서, 기존 이차전지를 대체 또는 보완 할 수 있는 방안도 검토되고 있다. PZT계 세라믹스는 높은 유전상수와 우수한 압전특성으로 전자세라믹스 분야에서 가장 널리 사용되어지고 있지만 $1200^{\circ}C$ 이상의 높은 소결온도 때문에 $1000^{\circ}C$ 부근에서 급격히 휘발되는 PbO로 인한 환경오염과 기본조성의 변화로 인한 압전 특성의 저하가 문제시 되고 있다. 또한 적층 세라믹스의 제작 시 구조적 특성상 내부전극이 도포된 상태에서 동시 소결이 필요한데, 융점이 낮은 Ag전극 대신 값비싼 Pd나 Pt가 다량 함유된 Ag/Pd, Ag/Pt 전극이 사용되고 있어 경제성이 떨어지는 단점을 갖게 된다. 순수 Ag 전극을 사용하거나 Ag의 비율이 높은 내부전극을 사용하기 위해서는 $900^{\circ}C$ 이하에서 소결되고 우수한 전기적 특성을 보이는 압전 세라믹스를 개발 하는 것이 필요하다. 따라서 본 연구에서는 압전특성이 우수한 $(Pb_{1-x}Cd_x)(Ni_{1/3}/Nb_{2/3})_{0.25}(Zr_{0.35}/Ti_{0.4})O_3$ 계의 조성을 설계하고, 소걸온도를 낮추기 위해서 2 단계 하소법을 이용하였다. 또한 $MnCO_3$, $SiO_2$, $Pb_3O_4$ 등을 소량 첨가하여 액상 소결 특성을 부여하여 소결 온도를 감소시키려는 시도도 하였다. 분말을 볼 밀링 (ball milling)을 통해 24시간 동안 혼합하고, 혼합된 분말은 $800^{\circ}C$에서 2시간 동안 하소하였다. 하소한 분말을 다시 72시간 동안 볼 밀링 하여 최종 분말을 얻었다. 최종 분말에 PVB를 첨가하여 직경 15mm의 디스크 형태로 성형한 후, 850~$975^{\circ}C$ 범위에서 온도를 변화시키면서 소결을 하였다. 최종 분말 및 소결된 시편을 XRD분석을 통하여 상을 확인하였고, SEM을 이용하여 미세조직을 관찰 하였다. 전기적 특성을 평가하기 위하여 두께를 1mm로 연마한 시편에 Ag 전극을 도포하여 $650^{\circ}C$에서 열처리한 후, 분극처리 하였다. 압전특성은 $d_{33}$-meter로 측정하였고, impedance analyzer를 이용하여 압전 특성 (전기기계결합계수 및 기계적품질계수)을 측정 하였다. 또한 강유전체 특성 평가 장치 (Precision-LC)를 이용하여 분극-전계 특성을 평가하였다. 이상의 연구를 통하여 소결 온도가 $900^{\circ}C$인 경우에서도 양호한 압전 특성을 확보 할 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.295-295
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• 2007

기계적 에너지를 전기적 에너지로 변화하는 에너지 변환소자인 압전 세라믹스는 액츄에이터, 변압기, 초음파모터, 초음파 소자 및 각종 센서로 응용되고 있으며, 그 응용분야는 크게 증가하고 있다. 최근 이러한 에너지 변화 소자는 앞으로 도래하는 ubiquitous, 무선 모바일 시대의 휴대용 전자제품, robotics, 항공우주, 자동차, 의료, 건축, MEMS 분야 등의 대체 에너지원으로 응용하기 위한 연구가 진행되고 있다. 특히 인간의 동작 등과 같은 일상적인 동작으로 필요한 전력을 얻을 수 있고, 세라믹 소자를 이용하기 때문에 전자노이즈가 발생되지 않을 뿐 아니라 반영구적으로 사용할 수가 있어서, 기존 이차전지, 연료전지를 대체 또는 보완 할 수 있는 방안도 검토되고 있다. PZT계 세라믹스는 높은 유전상수와 압전특성으로 전자세라믹스분야에서 가장 널리 사용되어지고 있지만 $1200^{\circ}C$이상의 높은 소결온도 때문에 $1000^{\circ}C$ 부근에서 급격히 휘발되는 PbO로 인한 환경오염과 기본조성의 변화로 인한 압전 특성의 저하가 문제시되고 있다. 또한, 적층 세라믹스의 제작 시 구조적 특성상 내부 전극이 도포된 상태에서 동시 소결이 필요한데, 융점이 낮은 Ag전극 대신 값비싼 Pd나 Pt가 다량 함유된 Ag/Pd, Ag/Pt 전극이 사용되고 있어 경제적인 문제가 발생하게 된다. 따라서 순수 Ag 전극을 사용하거나, Ag의 비율이 높은 내부 전극을 사용하기 위해서는 $950^{\circ}C$ 이하에서 소결되는 압전 세라믹스를 개발 하는 것이 필요하다. 따라서 본 연구에서는 압전특성이 우수한 $(Pb_{1-x}Cd_x)\;[(Ni_{1/3}/Nb_{2/3})_{0.25}Zr_{0.35}Ti_{0.4}]O_3$계의 조성을 설계하여, 소결온도를 낮추기 위해서 2단계 하소법을 이용하였다. 분말을 ball milling을 통해 24시간 동안 혼합하였다. 혼합된 분말은 $800^{\circ}C$에서 2시간 동안 하소하였다. 하소한 분말을 72시간 동안 ball milling 하여 최종 분말을 얻었다. 최종 분말에 PVB를 첨가하여 ${\Phi}21$ disk 형태로 성형한 후, $800{\sim}950^{\circ}C$ 소결을 하였다. 최종 분말 및 소결된 시편을 XRD분석을 통하여 상을 확인하였고, SEM을 이용하여 미세조직을 관찰하였다. 전기적 특성을 확인하기 위하여 두께 1mm로 연마한 시편에 Ag 전극을 도포하여 열처리한 후, 분극 처리하였다. 압전특성은 $d_{33}$ 미터로 측정하였고, impedance analyzer를 이용하여 주파수 및 impedance 특성을 측정하였다. 그 결과 $900^{\circ}C$에서 우수한 압전 특성 및 전기적 특성을 확보 할 수 있었다.

• Journal of Venture Innovation
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• v.5 no.4
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• pp.179-189
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• 2022

In the face of revolutionary changes in industry, the relationship between labor and income needs to be reconceptualized in the period of social revolution. The absolute decrease in labor due to the absence of labor is caused by automation, smartization, AI, robot labor, etc., which we must accept whether we want to or not. However, while gross social product and capital of the state or society increase, individual income is likely to decrease. During this transformation period, the state or politics must prepare for the problems caused by the decline in individual income. Until now, there have been various levels of discussion on social welfare or social security from the perspective of welfare or assistance. Attempts or studies at the experimental level have been conducted at the level of many countries or local governments and have found positive and negative effects. There is no basic income system that is widely implemented at the national level, and various discussions are taking place from a future-oriented perspective. Therefore, I propose to look at it from a new perspective based on the perspective so far. We explored that it is part of a positive approach to examine the importance and necessity of basic income in terms of working hours, quality of labor, income, quality of life, value of spare time, and work-life balance. The goal is to actively accept the absolute lack of working hours, replacement of mechanical labor, and polarization due to changes in the industry paradigm, and to look at the problems that come from a positive perspective. If we are going to accept it anyway, we should not look at these issues as short-sighted, but prepare them preemptively and establish a primitive plan from a long-term and overall perspective. Smartphones have changed the world over the past decade and have been lost, but wouldn't there be a lot of new discoveries? Shouldn't we think of it as a great opportunity to improve the quality of life through technological changes?

• Journal of The Korean Association of Information Education
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• v.6 no.2
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• pp.163-178
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• 2002

WBI as new instructional method is known to be superior to the traditional face-to-face education method with regard to cost, time and effectiveness of learning. However, WBI lacks the humanity education that teaches human nature such as cooperative spirit or morality, since WBI delivers the knowledge in a mechanical way. The objective of this study is to design and implement Web-based humanity education system that supplements WBI. The system is designed to promote the intimate relation, reliability, and openness between teacher and student. Also, this system encourages the students to experience an affirmative human relation through group activities. In additions, this system promotes parents to join together for improving their understanding of children's learning process.