• Korean Journal of Computational Design and Engineering
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• v.5 no.1
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• pp.42-49
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• 2000

This paper presents a solid modeling system that enables real time co-operative modeling and discussion on m between geographically separated designers. The modeling system is implemented using CORBA architecture and integrated in WWW with Java technology. The server objects use a commercial solid modeling kernel to provide modeling features and access database including product model data. The client is implemented using Java2 platform so that enables end-users access the system with web-browsers.

• Journal of the Korean Geophysical Society
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• v.4 no.1
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• pp.57-69
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• 2001

We have carried out a nondestructive close examination for the purpose of the structural safety diagnosis of the Three-Story Pagoda(Seokga Pagoda) in Bulkuk temple in the city of Kyungju, Kyungbuk, Korea. Ultrasonic wave velocities were measured at 456 points of the pagoda comprising 44 blocks to estimate the mechanical properties of rock blocks constituting the pagoda. The measured velocities have the range of 1217 to 4403 m/sec with the average of 3227 m/sec. The empirical relationship between the ultrasonic velocity and the uniaxial compressive strength yielded the estimation of strength of each block, ranging from 134 to 844 kg/cm^2 and averaging 463 kg/cm^2. With an assumption that the strength of each block is described as a random variables having a normal distribution, we calculated the probability of failure of rock blocks of the pagoda. Our investigation revealed that the probability of the structural failure due to the weight of higher blocks is very low. However, the probability of partial failure around contact area is substantial, which is consistent with the appearance that edges and the corners of some blocks were broken off. The platform under the body of the pagoda appeared to be structurally weak as the probability of tensile failure of the lower platform is up to 18%, and diagonal fractures are shown where the probability of failure is high.

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.2
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• pp.76-81
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• 2007

A novel multi-layer type micro gas sensor for $NO_X$ detection was designed and fabricated. Micro platform defined as type II-1 in this article for micro gas sensor was fabricated using the MEMS technology to meet the demanding needs of lower power consumption. Nano composite materials were fabricated with nanosized tin oxide powder and $\underline{m}$ulti-$\underline{w}$all $\underline{c}$arbon $\underline{n}$ano $\underline{t}$ube (MWCNT) to improve sensitivity. We investigated characteristics of fabricated multi-layer type micro gas sensor with $NO_2$ concentration variations at constant 2.2 V. Sensitivity (S) of micro gas sensor were observed to increase from 2.9, to 7.4 and 11.2 as concentrations of $NO_2$ gases increased from 2.4 ppm, to 3.6 ppm and 4.9 ppm. When 2.4 ppm of $NO_2$ gas was applied, response time and recovery time of micro gas sensor were recorded as 101 seconds and 142 seconds, respectively.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.10
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• pp.1157-1162
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• 2015

The maintenance function of Solar power plant is configured with Sensor devices, Gateway, and Maintenance Function Platform. In this paper, we designed gateway resource tree and service scenario to fit the Maintenance Function and demonstrated appropriate operation of the maintenance service through intelligent functional modeling.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.5
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• pp.273-280
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• 2011

In this paper, we describe the structural reinforcement approach of the throwing-type firefighter assistance robot which can be thrown into a fire site to monitor inside the place and search trapped people while ensuring a firefighter's safety. The reinforcement design is focused on high strength with low weight for the robot. The in-depth structural analysis of the platform is carried out to track down the weakest part, especially with the 1.8m height of drop test. The analysis is verified by comparing with the 1.8m height of the drop test of the throwing-type firefighter assistance robot. The optimal approach for improving the strength of the weakest part aims at topological equivalent and equivalently stress distributed shape.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.01a
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• pp.457-458
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• 2019

본 논문에서는 심장 박동 변이 (HRV: heart rate variability) 센서와 표준 기반 사물인터넷 (IoT: Internet of Things) 플랫폼을 활용한 스트레스 측정 시스템을 구현하고 그 활용 방법을 제안한다. HRV를 측정하기 위해 맥파 (PPG)센서와 오픈소스 하드웨어를 이용해 센싱 시스템을 구축하고 표준 사물인터넷 플랫폼을 이용하여 서버 시스템을 구축하였다. 추후 분석을 통해 유추한 스트레스 정도에 따라 플랫폼에 연결된 다양한 기기들을 이용하여 스트레스를 낮추기 위한 개인별 스트레스 관리 솔루션을 구현할 수 있음을 알 수 있다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.07a
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• pp.247-248
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• 2019

본 논문에서는 블루투스 비콘을 이용해 고소 작업장 등의 위험지역에서 작업자 추적 및 확인과 안전 벨트고리를 체결했는지 여부와 작업자의 행동에 따른 데이터를 추가로 수집하여 작업자의 행동 패턴을 분석하였다. IoT 국제 표준인 oneM2M을 기반으로 IoT Device와 Application을 연결하는 중간 매개체로 모비우스 플랫폼을 사용해 시스템을 구축하였다. 또한, 본 연구팀의 선행 연구에서 작업자 위험 행동분류 시스템을 개선할 수 있는 연구 결과를 비교하였다.

• Korean Journal of Chemical Engineering
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• v.35 no.11
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• pp.2232-2240
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• 2018

We applied methanesulfonic acid (MSA) as a green catalyst to produce levulinic acid (LA) from monomeric sugars. To optimize reaction factors and assess the effect of reciprocal interactions, a statistical experimental design was applied. Optimized result of 40.7% LA yield was obtained under the following conditions: 60 g/L galactose, 0.4 M MSA at $188^{\circ}C$ for 26.7 min. On the other hand, 66.1% LA yield was achieved under 60 g/L fructose and 0.4 M MSA at $188^{\circ}C$ for 36 min conditions. For the effect of combined severity factor on the LA yield from galactose, the LA yield showed a peaked pattern, which was linearly increased until a CSF 3.2 and then diminished with a high CSF. Moreover, it was closely fitted to a non-linear Gaussian peak pattern with a high regression value of 0.989. These results suggest that MSA and galactose, derived from marine red macro-algae, can potentially be applied for the conversion into platform chemicals.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.4
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• pp.3962-3969
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• 1975

1. When the frame of the experimental apparatus was directly fixed on the platform, result from the spectrum density analysis showed that the generated vibration frequecy of the system was nearly-same as the system's own characteristic vibration frequency, 80Hz, in the case of the forcing vibration frequency was 7.5 to 22.5Hz. The reduction ratio of acceleration by balanced type model compare to non-balanced type one was 26.66 percent. 2. When the frame of experimental apparatus was fixed on the platform with putting a shock absorbing rubber between the frame and the platform, the generated vibration frequency of the system was same as forcing vibration frequency. When either frequency or the amplitude of the forcing vibration was increased, the acceleration ratio was increased too. The average reduction ratio was resulted 44.77 per cent. It was concluded that this method of acceleration measurement(the method using a shock absorbing rubber) was a reaonable method, because actual machine will work under such condition. As the vibration frequency and aptitude were increased, the absolute magnitude of acceleration was increased. 3. unbalanced rotating parts, and unbalanced moment of inertia of links were supposed to be causing factors of residual vibration in spite of using the balanced type oscillating mole drainer. This fact suggested that the attachment of the counter weight on the rotating parts which satisfy the condition mw$.$rw=m0e, was necessary. And also, it was expected that the shock absorbing effect could be improved by putting the shock absorbing materials between the moving parts and their supports.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.2
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• pp.980-992
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• 2019

This paper describes a model test and numerical simulation of a 750-kW-semi-submersible platform wind turbine under several wind and wave conditions for validation of the numerical simulation model. The semi-submersible platform was designed to support the 750-kW-wind turbine class and operate at a water depth of 50 m. The model tests were performed to estimate the performance characteristics of the wind turbine system in the wide tank of the University of Ulsan. Motions and loads of the wind turbine system under the wind and wave conditions were measured and analyzed. The NREL-FAST code was used to simulate the wind turbine system, and the results were compared with those of the test model. The results demonstrate that the numerical simulation captures noticeably the fully coupled floating wind turbine dynamic responses. Also, the model shows a good stability and small responses during waves, wind, and operation of the 750-kW-floating offshore wind turbine.