• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.1-12
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• 2017

As the current ground transportation system becomes saturated, there is a need to develop a roadable personal air vehicle (PAV). Therefore, researches for PAV development and operation system development are being actively carried out in various countries around the world. PAV, the next generation transportation system, is a new concept of personal transportation that combines ground transportation, air traffic, and IT industry. Also, the development of PAV can solve the saturation of traffic congestion and shorten the travel time dramatically. In this study, we analyzed the certification criteria of FAR Part 23, which is going to be revised, and analyzed the patents and folding mechanism of Terrafugia Transition and Aeromobil 3.0, which are the most advanced of roadable PAV. Also, we used $OpenVSP^{(R)}$ for the reverse configuration design of the existing Terafugia transition and Aeromobile 3.0. Aerodynamic analyses were performed for the reverse configuration design using the $XFR5^{(R)}$ program.

• Journal of Korean Institute of Industrial Engineers
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• v.23 no.4
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• pp.803-816
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• 1997

In this paper we propose a new approach far part families considering multiple attributes of parts in the design and operating stage of flexible manufacturing systems. We first represent the relationship of parts and the relative attributes using fuzzy membership function, AHP method and normalization. As a result, more realistic nonbinary data of the relationship is obtained. Then we group parts into part families based on the nonbinary data using fuzzy $\alpha$-cut and new similarity coefficient method. The performance of our method is compared numerically with others.

• Korean Journal of Environmental Agriculture
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• v.23 no.4
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• pp.234-239
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• 2004

[ $NO_3$ ]-N and T-N removal rates of cattail wetland cells were compared with those of reed wetland cells. The examined cells were a part of a pond-wetland system composed of two ponds in series and six wetland cells in parallel. Each wetland cell was 25m in length and 6m in width. Cattails (Typha angustifolia) were transplanted into three cells and reeds Phragmites australis) into another three ones in June 2000. Water of Sinyang stream flowing into Kohung Estuarine lake located in the southern part of the Korean Peninsula was pumped into the primary pond, its effluent was discharged into the secondary pond Effluent from the secondary pond was funneled into each cell. Two cattail and reed cells were chosen for this research. Water quantity and quality of influnt and effluent were analyzed front May 2001 through October 2001. The volume of influent and effluent of the cells averaged about $20.0\;m^3/day$ and $19.3\;m^3/day$, respectively. Hydraulic retention time was approximately 1.5 days. Influent $NO_3$-N concentration for the four cells averaged 2.39 mg/L. Effluent $NO_3$-N concentration far the cattail and reed cells averaged 1.74 and 1.78 mg/L, respectively. Average $NO_3$-N retention rate for the cattail and reed cells by mass was 30 and 29%, respectively. Influent T-N concentration far the four cells averaged 4.13 mg/L. Effluent T-N concentration for the cattail and reed cells averaged 2.55 and 2.61 mgL respectively. Average T-N retention rate for the cattail and reed cells by mass was 39 and 38%, respectively. $NO_3$-N and T-N concentrations in effluent from the cattail cells were significantly low (p=0.04), compared with those from the reed cells. Cattail wetland cells were more efficient for $NO_3$-N and T-N abatement than reed ones.

• Journal of Advanced Navigation Technology
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• v.22 no.2
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• pp.111-122
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• 2018

At present, the ground transportation system is saturated in many countries including Korea. To overcome this problem, many researches of developing a roadable personal air vehicle (PAV) are being carried out to alleviate traffic congestion and to accomplish door-to-door mobility through three-dimensional traffic system. In this study, the thrust-to-weight ratio, the wing loading, and the power-to-weight ratio that are major design parameters for the sizing of roadable PAVs were calculated under the constraints of ground roll, climb rate, maximum cruise speed, service ceiling, stall speed. Also, in the sizing process, the study was conducted to determine the design point using the graphs of thrust-to-weight ratio, wing loading, power-to-weight ratio, and brake horse power for the mission profiles considering domestic environments and the FAR PART 23 which is the GA class aircraft certification standard.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.9 s.186
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• pp.119-126
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• 2006

This paper addresses the methodology development far the automated machining setup planning system using case-based reasoning(CBR). The case-based reasoning is used to develop a setup planning system. which consists of part input and representation module, case retrieval module, and case adaptation module. We present new approaches in the part input and representation module and the case retrieval module focusing on the similarity index determination. An illustrative example is included to demonstrate the proposed method.

• Journal of Power System Engineering
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• v.16 no.2
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• pp.17-23
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• 2012

The steady three-dimensional computational thermal flow analysis using standard k-${\varepsilon}$ turbulence model was carried out to investigate the heat transfer characteristics of a cabin cooler for a commercial vehicle. The heat exchanging method of this cabin cooler is to use the cooling effect of a thermoelectric module. In view of the results so far achieved, the air system resistance of a cabin cooler is about 12.4 Pa as a static pressure, and then the operating point of a cross-flow fan considering in this study is formed in the comparatively low flowrate region. The air temperature difference obtained from the cold part of an thermoelectric module is about $26^{\circ}C$, and the cooling water temperature difference obtained from the hot part of an thermoelectric module is about $3.5^{\circ}C$.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.9 s.186
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• pp.76-83
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• 2006

Machining accuracy is closely related with tool deflection induced by cutting forces. In this research, cutting forces and tool deflection in end milling are expressed as a closed form of tool rotational angle and cutting conditions. The discrete cutting fores caused by periodic tool entry and exit are represented as a continuous function using the Fourier series expansion. Tool deflection is predicted by direct integration of the distributed loads on cutting edges. Cutting conditions, tool geometry, run-outs and the stiffness of tool clamping part are considered together far cutting forces and tool deflection estimation. Compared with numerical methods, the presented method has advantages in prediction time reduction and the effects of feeding and run-outs on cutting forces and tool deflection can be analyzed quantitatively. This research can be effectively used in real time machining error estimation and cutting condition selection for error minimization since the form accuracy is easily predicted from tool deflection curve.

• Publications of The Korean Astronomical Society
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• v.28 no.2
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• pp.17-23
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• 2013

Song I-Yeong (1619 ~ 1692), who was an astronomy professor of Gwansanggam (觀象監, Bureau of Astronomy), created the Honcheonsigye (渾天時計, Armillary Clock) in 1669 (10th year of King Hyeonjong Era). Honcheonsigye was a unique astronomical clock which combined an armillary sphere, the traditional astronomical instrument of the Far East, with the power mechanism of western alarm clock. The clock part of this armillary clock is composed of two major parts which are the going-train, power unit used the weight, and the time signal system in a wooden case. The time signal system is composed of four parts which are the time-annunciator, the striking train, the 12 different time-announcing medallions and the sound bell. This clock has been neglected for many years and its several components have been lost. This study is to understand the structure of time signal system and suggests the restoration process.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.3
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• pp.325-330
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• 2010

In the fields of design within civil engineering, BIM based Utilization of 3D object model is still far from commercialization. In this paper, BIM based 3D object model is composed for PSC box girder, super structure of railway bridge. The basic unit of the model is part model. The part model is the minimum unit model. And it has hierarchy to reflect the characteristics of structures. Change orders of structural designer must be reflected quickly in the 3D object model. Repetitive change orders are occurred in actual construction process. To prepare that, we classified design variables to parameters. Change orders of structural designer can be reflected quickly in the 3D object model because those parameters are related with information of 3D object model. In this paper, we studied various benefits of BIM based design method with 3D object model in the fields of design within civil engineering, and proposed the efficient application method of 3D object model for PSC box girder.

• Journal of the Korean Professional Engineers Association
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• v.19 no.1
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• pp.25-32
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• 1986

The number of visiters to Bukhan Mt. national park, generation quantity of solid waste and collection system were researched to consider a counterplan for the pollution control of the national park and study for developing the effective treatment of solid waste was tried through the proximate analysis of each component containing. Results obtained in this study were summerized as follows; The great part of visitors go on an excursion to the Bukhan Mt. national park during July and August and also, the solid waste was generated nearly a half of the total amount at the same period. The major collection facilities in the national park were waste basket and incineration box. But the incineration box was too large in volume and very far in distance, and its collection period was irregular, so it was cause to the congestion of solid waste and bad smell and dirty. Therefore, to complete collection of solid waste, we must set up the waste basket which able to find within 40～50m from the origination place of solid waste and induce the visitors to throw the solid waste. It was obtained as moisture content: 48.5 wt%, volatile solid: 28.4wt％, fixed solid: 23.1 wt％, lower heating value: 1,320kca1/kg from experimental analysis of solid waste. According to this analysis, the incineration operation is possible, but the generation quantity of solid waste was too small to construct incineration plant for heat recovery. It was found that it is suitable for the aerobic composting by mixing with the night soil which generate in the national park after the recovery of resources such as metals, glasses and plastics.