• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.4
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• pp.382-390
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• 2011

Smart sensors embedable in composite wind turbine blades have been required to be researched for monitoring the health status of large wind turbine blades during real-time operation. In this research, the feasibility of packaged FBG sensor probes was studied through the experiments of composite blade trailing edge specimens in order to detect cracking and debonding damages. The instants of cracking and debonding generated in the shear web were confirmed by rapid changes of the wavelength shifts from the bare FBG sensor probes. Packaged FBG sensor probes were proposed to remove the fragile property of bare FBG sensor probes attached on composite wind blade specimens. Strain and temperature sensitivity of fabricated probes installed on the skin of blade specimen were almost equal to those of a bare FBG sensor. Strain sensitivity was measured to be ${\mu}{\varepsilon}$/pm in a strain range from to 0 to 600 ${\mu}{\varepsilon}$, and the calculated temperature sensitivity was to be 48 pm/$^{\circ}C$ in the heating test up to 80 degree.

• Journal of the Korean Society of Radiology
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• v.12 no.3
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• pp.389-395
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• 2018

The study attempted to use computed tomography images to determine the usefulness of the reduction in the axial reduction algorithm in the event of a metallic artifacts reduction in the image of the beam-hardening effect, which is known as the most effective method of reducing metallic artifact reduction in the image and the reduction of the metal produced in this study. As a result, the result is increased to 140 kVp to reduce the value of the CT value by 0.02 to 0.05 %, resulting in decreased axial effect (P > 0.05). The CT value decreased from 12.4 to 26.9 % when applied to the reduction of the metallic. 12.4 to 26.9 % (p<0.05). In addition, in the qualitative assessment by the clinical trial evaluation, it was assessed as 1.8 points after applying the MAR algorithm, In the resolution of resolution and contrast evaluations, the estimation of the decrease in metallic artifact effects was assessed as the metal was assessed to be scored 7.2 points after the MAR algorithm was evaluated. Therefore, in case of artifacts due to irreversible beam hardening effect, it is useful to reduce artifacts caused by beam hardening effect by using various methods derived from existing researches and scanning by applying the metal artifact reduction algorithm proposed in this experiment.

• Information Systems Review
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• v.10 no.2
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• pp.137-158
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• 2008

Rapid development of various information technologies creates new opportunities in online and offline markets. In this changing market environment, customers have various demands on new products and services. Therefore, their power and influence on the markets grow stronger each year. Companies have paid great attention to customer relationship management. Especially, personalized product recommendation systems, which recommend products and services based on customer's private information or purchasing behaviors in stores, is an important asset to most companies. CRM is one of the important business processes where reliable information is mined from customer database. Data mining techniques such as artificial intelligence are popular tools used to extract useful information and knowledge from these customer databases. In this research, we propose a recommendation system that predicts customer's purchase intention. Then, customer's purchasing intention of specific product is predicted by using data mining techniques using receipt data set. The performance of this suggested method is compared with that of other data mining technologies.

• Economic and Environmental Geology
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• v.50 no.2
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• pp.159-170
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• 2017

The temporal and spatial temperature distribution of the heat storage mortar made of porous feldspar was measured and the thermal properties and electricity consumption were analyzed. For the experiment, two real size chambers (control model and test model) with hot water pipes were constructed. Two large scale models with hot water pipes were constructed. The surface temperature change of the heat storage layer was remotely monitored during the heating and cooling process using infrared thermal imaging camera and temperature sensor. The temperature increased from $20^{\circ}C$ to $30^{\circ}C$ under the heating condition. The temperature of the heat storage layer of the test model was $2.0-3.5^{\circ}C$ higher than the control model and the time to reach the target temperature was shortened. As the distance from the hot water pipe increased, the temperature gap increased from $4.0^{\circ}C$ to $4.8^{\circ}C$. The power consumed until the surface temperature of the heat storage layer reached $30^{\circ}C$ was 2.2 times that of the control model. From the heating experiment, the stepwise temperature and electricity consumption were calculated, and the electricity consumption of the heat storage layer of the test model was reduced by 66%. In the cooling experiment, the surface temperature of the heat storage layer of the test model was maintained $2^{\circ}C$ higher than that of the control model. The heat storage effect of the porous feldspar mortar was confirmed by the temperature experiment. With considering that the time to reheat the heat storage layer is extended, the energy efficiency will be increased.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.10a
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• pp.73-77
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• 1996

정보는 의사결정자들의 수주에 있을 때 기업에 있어 강력한 경쟁무기가 된다. 의사결정자들의 정보에 대한 이러한 필요성을 충족시키기 위해서 데이타는 운영시스템(Operational System)에서 추출되어 데이타웨어하우스에 저장된다. 데이타웨어하우스는 핵심 비지니스영역(key business dimension)에 의해 정리된 historical data를 저장한다. 이러한 의사결정자들을 위한 데이타웨어하우스 정보의 전달은 기존의 클라이언트/서버 시스템 하에서는 많은 지원을 요구한다. 즉 기존 클라이언트/서버 시스템 하에서는 사용자들의 접근을 위해 데이타가 추출되고 조직화되어지고 나면, 반드시 분석 소프트웨어가 각 사용자의 컴퓨터에 설치되어야 하고 외부의 사용자를 위한 새로운 운영자가 고용되어야 한다. 사용자의 다양한 요구 그리고 계속적 사용자의 교체는 사용자 지원에 있어 심각한 기업부담으로 작용한다. 또한 클라이언트/서버 시스템에서는 기업외부의 정보 이용자들에게 정보를 제공하는데 있어 장소적 한계점을 가지고 잇다. 인트라넷과 인터넷은 이러한 클라이언트/서버 시스템 환경의 문제에 대해 해답을 제시한다. 인트라넷은 데이타웨어하우스로의 접근을 간단히 할뿐만 아니라 의사결정자들의 정보의 공유와 상호분석의 새로운 단계를 제공한다. 그리고 인터넷은 기업 외부 어디에서나 기업이 제공하는 정보를 이용하고자 하는 사람들에게 접근의 편의성을 제공한다. 즉 데이타웨어하우스의 목표와 인트라넷, 인터넷의 목표는 데이타로의 손쉬운 접근이라는 점에서 동일하다. 이러한 점에 착안하여 인트라넷과 인터넷하에서 운용되는 데이타웨어하우스 시스템 구축을 위한 방안을 제시하고자 한다.다(학생군:8.16kg 작업자군:12.9kg). 심박수를 이용한 생리학적 연구에서는 평균 심박수가 거의 100 이하를 유지하므로써 피실험자들이 8시간 작업기준으로 보아 무리가 없는 최대허용 하중을 결정하였음을 보였다. 또한 각 운반작업에 대한 최대허용 하중을 예측하는 회귀모형을 제시하였다.아직 정립되어 있지 않은 분산 환경하에서의 관계형 데이타베이스의 데이타관리의 분류체계를 나름대로 정립하였다는데 그 의의가 있다. 또한 이것의 응용은 현재 분산데이타베이스 구축에 있어 나타나는 기술적인 문제점들을 어느정도 보완할 수 있다는 점에서 그 중요성이 있다.ence of a small(IxEpc),hot(Tex> SOK) core which contains two tempegatlue peaks at -15" east and north of MDS. The column density of HCaN is (1-3):n1014cm-2. Column density at distant position from MD5 is larger than that in the (:entral region. We have deduced that this hot-core has a mass of 10sR1 which i:s about an order of magnitude larger those obtained by previous studies.previous studies.업순서들의 상관관계를 고려하여 보다 개선된 해를 구하기 위한 연구가 요구된다. 또한, 준비작업비용을 발생시키는 작업장의 작업순서결정에 대해서도 연구를 행하여, 보완작업비용과 준비비용을 고려한 GMMAL 작업순서문제를 해

• Journal of Energy Engineering
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• v.22 no.2
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• pp.96-104
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• 2013

Coal gasification is considered as one of the best alternatives among clean coal technology and new concept next generation technologies are under being developed to achieve low cost as well as high efficiency. In this study we have developed double swirl multi-burner as part of the development of low cost compact gasifier. We installed new concept multi-burner with pulverized coal distributor to the body of existing gasifier for burner test. Gasification test was performed under the condition of $6.4{\sim}7.2kg/cm^2$ and $1170{\sim}1300^{\circ}C$ by using Indonesian ABK (sub-bituminous) coal to get operation condition of new concept multi-burner. Our interest was focused to ensure a stable operating condition rather than the gasifier performance evaluation. As a result, we were able to achieve the carbon conversion of 84% and the cold gas efficiency of 52.1% at the stable operating conditions.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.1
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• pp.1-10
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• 1999

The north-west sea area of Cheju Island is where originate two layer current in the summer season. The case of the fishing operations in this sea area is almost impossible for normal expansion of the net gear for shooting net, and is happened to be frequent occasions for rise of tension suddenly in purseline by changes of the net shapes in the operation. Therefore, the safety of the operations is often obstructed by the above mentioned. In connection with the above, model experiments on the purse seine in the circulating water tank was carried out in comparison and analysis on the changes of tension in the pruseline by deformation of purse seine in the sea area of two layer current. THe results obtained are as follows;In the case of the required time for pursing of 20 minutes in the no current set, the increasing curve for tension of purseline can be expressed as:Y=0.0004x3+0.0098x2+0.3000x(r=0.9989)where Y is tension(metric tons) of a purseline, x is required time(minutes) for pursing. And, the maximum value of tension in this time was an increase of 31.3 percent at 15 minutes, and was a decrease of 30.3 percent at 30 minutes than that of 20 minutes.When the bottom margin of net is held on the position in velocity of 0.5 knot at three-eighths of net in the bottom current to the net height, the maximum tension of the required time for pursing of 30 minutes in tight set and loose set were decrease of 29.5 percent and 28.7 percent respectively than that of 20 minutes.The work load during the required time for pursing of 20 minutes were calculated 5.79×106 kgf·m in no current set, 7.89×106 kgf·m in tight set and 5.15×106 kgf·m in loose set, therefore it was an increase of 22.3 percent in tight set, and was a decrease of 11.1 percent in loose set than that of the no current set. Where tight set and loose set is a range of the bottom current with velocity of 0.5 knot at three-eighths of net to the net height.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.3
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• pp.134-147
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• 2006

A model experiment using circulation water channel was carried out to investigate the dynamic characteristics of bottom trawl net which can be used in sea mount of North Pacific. Hydrodynamic resistance and shape variation according to the flow velocity and angle of hand rope transformation for net were measured, and experimental value was analyzed as the value of full-scale bottom trawl net. The results summarized are as follows; At the $30^{\circ}$ of angle of hand rope to net, hydrodynamic resistance varied from 0.5kgf to 2.68kgf as the flow velocity increased between 0.31m/s and 0.92m/s, and formula of hydrodynamic resistance for the model net was $F_m=3.04\;{\cdot}\;{\upsilon}^{1.53}$. At the fixed angle of hand rope, Net height was low and Net width was high according to the increase of flow velocity, and in addition, vertical opening was low and Net width was high by the increase of angle of hand rope at the fixed flow velocity. At the $30^{\circ}$ of angle of hand rope to net, net opening area was $0.214m^2$ as flow velocity was 0.61m/s, and formula of net opening area for the model net was $S_m=-0.22{\upsilon}+0.35$. At the $30^{\circ}$ of angle of hand rope to net, catch efficiency seemed to be highest as $0.319m^3/s$ of filtering volume at the 0.76m/s(51kt's) of flow velocity. Shape variation of net showed the gradual laminar transform for the variation of flow velocity but there needed some improvements due to the occurrence of shortening at the ahead of wing net.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.4
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• pp.281-289
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• 2011

The purpose of this study is to identify the flow resistance of the bottom trawl net. The bottom trawl net being used in the training ship of Chonnam National University was selected as a full-scale net, and model nets such as 1/10, 1/25 and 1/50 of the actual net were made. Total resistance of the net part, the height of the net mouth and the flow resistance of components of the net such as wing, bag and cod-end part was measured, converted into full-scale and compared. Additionally, the model rule of Tauti (1934), which has been most frequently used in fishing net modeling experiments, was applied to interpret flow resistance and scale effect of model experiment was investigated. Presumed that the flow resistance R is $R=kS{\upsilon}^2$ against the flow velocity of each net ${\upsilon}$, resistance coefficient k was calculated by substituting R, ${\upsilon}$ and S of the net. From the result, it was found that k decreases exponentially when u increases which makes $k=c{\upsilon}^{-m}$. Whereas m of each net is ranged between 0.13-0.16 and there was not significant difference between nets. c does not show big difference in 1/10 and 1/25 model and the value itself was relatively bigger than in 1/50 model. The height of the net mouth of 1/25 and 1/50 model net h decreases exponentially according as ${\upsilon}$ increases to make $h=d{\upsilon}^{-n}$. Whereas d and n values were almost same in two nets. Additionally, when resistance of cod-end, wing and bag part in 1/25 and 1/50 model nets, both nets showed big resistance in bag part when flow is 1m/s as more than 60%. Wing and cod-end part showed almost same value or wing part had little bit larger value. On the other hand, when reviewing the reasons why both models showed difference in 1/50 model while c value against the resistance coefficient k did not show big difference in 1/10 and 1/25 model, it is inferred that the difference occurred not from material difference but from the difference in net size according to scale. It was judged that they are the scale effects concomitant to the model experiments.

• 대한공업교육학회지
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• v.39 no.2
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• pp.122-143
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• 2014

The purpose of this research were to develop program of elementary school technology education using history of technology and to learn about its effect. In order to accomplish the purpose of the research, we developed the program by referring to various records and perform the qualitative experiment study through several questionnaire, pictures and materials, to learn about the program effect. The research took the mixed-model design, consisted of collection of quantitative data by Likert scale and collection of qualitative data including the open-ended questions. And the research results were as below. First, development of elementary school technology education program using history of technology was developed as program for 12 hours, 12 themes, for the elementary levels. Second, seeing the result of program of elementary school technology education using history of technology, the program for history of technology for the primary school students, a majority of answers showed high satisfaction about the program, giving answers such as 'I want to do it again following hands on minds on activity.' Third, according to the analysis on the qualitiative evidence of the program, students were found to take pictures with hands on minds on activity camera obscura with much interest and curiosity. Many students are seen to complete the task on their own with a great a look of self-satisfaction, understanding the principle of camera.