• 한국산학기술학회논문지
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• 제1권2호
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• pp.41-48
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• 2000

최근 산업현장의 모든 부분에서 자동화의 요구가 급격하게 증가되고 있다. 지금까지의 사격장 시스템은 정적인 환경을 중심으로 설계되어져 왔다. 그러나, 실제의 사격상황은 목표물이 동적이므로 다른 사격 환경 변화가 요구된다. 본 연구에서는 동적인 사격환경을 구현하기 위해 1개 사로에 4대의 타겟을 설치하여 사격순서를 순차 및 비순차로 구분하고 사격시간을 가변적으로 조정할 수 있게 하였다. 그리고. 자동차 및 빌딩 자동화에 많이 응용되고 있는 CAN(Controller Area Network)을 이용함으로써 효율적인 통신을 가능하게 하였다. CAN은 높은 데이터 전송률과 안정성을 제공할 수 있어 다수의 ECU(Electric Control Unit)를 상호 연결하여 분산된 실시간 제어를 효율적으로 지원할 수 있다.

• 제어로봇시스템학회논문지
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• 제18권4호
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• pp.321-327
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• 2012

This paper presents a comparative analysis on three different types of performance indices of obstacle detection for an overlapped ultrasonic sensor ring. Due to beam overlap, the entire sensing zone of each ultrasonic sensor can be divided into three smaller sensing subzones, which leads to significant reduction of positional uncertainty in obstacle detection. First, the positional uncertainty in obstacle detection is expressed in terms of the area of a sensing subzone, and type 1 performance index is then defined as the area ratio of side and center sensing subzones. Second, based on the area of a sensing subzone, type 2 performance index is defined taking into account the size of the entire range of obstacle detection as well as the degree of the positional uncertainty in obstacle detection. Third, the positional uncertainty in obstacle detection is now expressed in terms of the length of the uncertainty arc spanning a sensing subzone, and type 3 performance index is then defined as the average value of the uncertainty arc lengths over the entire range of obstacle detection. Fourth, using a commercial low directivity ultrasonic sensor, the changes of three different performance indices depending on the parameter of an overlapped ultrasonic sensor ring are examined and compared.

• 한국환경과학회지
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• 제13권6호
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• pp.519-525
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• 2004

Air pollution from the Daegu industrial complex (Die) in Korea has been a common nuisance and cause of complaints for nearby residents. The current study measured the indoor and outdoor levels of six VOC (benzene, toluene, ethylbenzene, and three isomeric xylenes) at two residential areas with a different proximity to the ODIC, plus the ambient levels at two industrial areas within the boundary of the DDIC. The QA/QC program included the range of correlation coefficient (0.94-0.99) for calibration curves, within the permissible range. Toluene was the most abundant VOC in the ambient air both in residential and industrial areas. Both indoor and outdoor air concentrations of all target VOC except benzene were higher in residential area near the DIC compared to that further away from the DIC. Moreover, the ambient air concentrations of all target VOC except benzene for two industrial sites (A and B) were significantly higher than the outdoor or indoor air concentrations in the two residential areas. The findings further suggested that VOC ambient levels measured in a residential area near the DIC be used as a potential indicator of odor-causing unidentified air pollutants transported from the DIC. Moreover, it was found that the elevated ambient toluene levels outweighed the indoor sources with respect to the environmental exposure of residents nearby the DIC. However, in the residential area further away from the DIC, the toluene indoor sources outweighed the outdoor sources.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.61-64
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• 2008

The present study of these experiments are close examination of spray characteristics that are continuous liquid jet and modulated pressure pulse liquid jet. The experiments were conducted using water, over a range of cross-flow velocities from 42${\sim}$136 m/s, with injection frequencies of 35.7${\sim}$166.2 Hz. Between continuous cross-flow jet and pressure pulsed cross-flow jet for characteristics of penetration, breakup point, spray angle and macro spray shape are investigated experimentally. In cross-flow field, main parameter of liquid jet for breakup was cross-flow stream rather than pressure pulse frequency. As oscillation of the periodic pressure that could make liquid jet moved up and down, the mixing efficiency was increased. Also, a bulk of liquid jet puff was detected at upper field of liquid surface. So, this phenomenon has a good advantage of mixing spray from concentration of center area to outer area. Because of pressure pulsation frequency, an inclination of SMD for the structured layer was evanescent. Cross-sectional characteristics of SMD at downstream area were non-structured distributions. Then cross-sectional characteristics of SMD size were about same tendency over a range that is effect of spray mixing. The tendency of volume flux value for various frequency of pressure pulse was same distribution. And volume flux was decreased when the frequency of pressure pulse increase.

• 한국분무공학회지
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• 제14권2호
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• pp.59-64
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• 2009

These experiments are close examination of spray characteristics that are continuous liquid jet and modulated liquid jet. The experiments were conducted using water, over a range of crossflow velocities from $42{\sim}l36\;m/s$, with modulation frequencies of $35.7{\sim}166.2\;Hz$. Between continuous crossflow jet and modulated cross-flow jet of penetration, breakup point, spray angle and macro spray shape are experimentally investigated with image analysis. In cross-flow field, main parameter of liquid jet for breakup was cross-flow stream rather than modulation effect. As oscillation of the periodic pressure that could make liquid jet moved up and down, the mixing efficiency was increased. Also, a bulk of liquid jet puff was detected at upper field of liquid surface. So, this phenomenon has a good advantage of mixing spray from concentration of center area to outer area. Because of modulation frequency, SMD inclination of the structured layer was evanescent. Cross-sectional characteristics of SMD at downstream area were non-structured distributions. Then cross-sectional characteristics of SMD size were about same tendency over a range that is effect of spray mixing. The tendency of volume flux value for various modulation frequency was same distribution. And volume flux was decreased when the modulation frequency increase.

• 한국통신학회논문지
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• 제36권7A호
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• pp.669-677
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• 2011

IEEE 802.15.4 표준에서 슈퍼프레임 구조는 활성화 구간과 비활성화 구간을 사용하여 낮은 전력 소모를 제공하도록 한다. 하지만 슈퍼프레임의 활성화 구간 동안 통신하는 노드들은 코디네이터와의 거리와는 상관없이 동일한 전송 반경을 샤용하여 데이터를 전송하기 때문에 불필요한 에너지를 낭비하게 된다. 본 논문에서 코디네이터는 통신 영역을 4개의 영역으로 나누고 각 영역에 포함되어 있는 노드는 코디네이터가 전송한 비콘 메시지를 확인하여 송신전력을 설정함으로써 데이터 전송에서 발생하는 전력 소모를 최소화한다. 또한, Cross Layer 프로토콜을 통하여 PAN(personal Area Network) 영역을 구성하도록 하여 메시지 전송 충돌(collision) 현상을 최소화하였다.

• Journal of information and communication convergence engineering
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• 제2권1호
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• pp.58-60
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• 2004

Sea level variations and sea surface circulations in the Korean seas were observed by Topex/Poseidon altimeter data from 1993 through 1997. In sea level variations, the West and South Sea showed relatively high variations with comparison to the East Sea. Then, the northern and southern area in the West Sea showed the range of 20∼30cm and 18∼24cm, and the northern west of Jeju island and the southern west of Tsushima island in the South Sea showed the range of 15∼20cm and 10∼15cm, respectively. High variations in the West Sea were results to the inflow in sea surface of Yellow Sea Warm Current (YSWC) and bottom topography. Sea level variations in the South Sea were due to two branch currents (Jeju Warm Current and East Korea Warm Current) originated from Kuroshio Current (KC). In sea surface circulations, there existed remarkably three eddies circulations in the East Sea that are mainly connected with North Korea Cold Current (NKCC), East Korea Warm Current (EKWC) and Tushima Warm Current (TWC). Their eddies are caused basically to the influence of currents in sea surface circulations; Cyclone (0.03 cm/see) in the Wonsan bay off shore with NKCC, and anticyclone (0.06 cm/see) in the southwestern area of Ulleung island with EKWC, and cyclone (0.01 cm/see) in the northeastern area of Tushima island with TWC, respectively.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.879-881
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• 2003

Sea level variations and sea surface circulations in the Korean seas were observed by Topex/Poseidon altimeter data from 1993 through 1997. In sea level variations, the West and South Sea showed relatively high variations with comparison to the East Sea. Then, the northern and southern area in the West Sea showed the range of 20${\sim}$30cm and 18${\sim}$24cm, and the northern west of Jeju island and the southern west of Tsushima island in the South Sea showed the range of 15${\sim}$20cm and 10${\sim}$15cm, respectively. High variations in the West Sea was results to the inflow in sea surface of Yellow Sea Warm Current (YSWC) and bottom topography. Sea level variations in the South Sea was due to two branch currents(Jeju Warm Current and East Korea Warm Current) originated from Kuroshio Current (KC). In sea surface circulations, there existed remarkably three eddies circulations in the East Sea that are mainly connected with North Korea Cold Current (NKCC), East Korea Warm Current (EKWC) and Tushima Warm Current(TWC). Their eddies are caused basically to the influence of currents in sea surface circulations; Cyclone (0.03 cm/sec) in the Wonsan bay off shore with NKCC, and anticyclone (0.06 cm/sec) in the southwestern area of Ulleung island with EKWC, and cyclone (0.01 cm/sec) in the northeastern area of Tushima island with TWC, respectively.

• Membrane and Water Treatment
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• 제14권1호
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• pp.47-54
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• 2023

In this study, high concentrations of cadmium-containing wastewater were treated by electrodialysis (ED) with a channel stack. The limiting current density (LCD), cadmium removal efficiency, and current efficiency were investigated under each experimental condition according to the Reynolds number (Re), membrane area, and pH. With the increase in the film area to 111, 333, 555, and 777 cm² at Re (109.1), LCDs decreased to 408.11, 44.45, 35.32, and 13.64 A/m², respectively. The highest cadmium removal efficiency (99.6%) and current efficiency were obtained for the membrane area of 111 and 777 cm², respectively. Under changing Re in the pH range of 1 to 4, Re and LCD were proportional under the same pH condition, and pH and LCD tended to be inversely proportional under the same Re condition. Cadmium removal rate was the best at the pH range 3 - 4. It has been found that ED with channeled stacks can be successfully applied to treat wastewater containing high concentrations of cadmium.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.93-94
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• 2022

Although various studies about indoor positioning systems, such as beacon and Wifi, have been conducting for indoor positioning of workers at construction sites, these systems have limitations in terms of accuracy or economics. To overcome these limitations, geomagnetic field sequence-based indoor positioning technology can be a good alternative. However, it is necessary to correct the geomagnetic field near the construction material stocking area since the geomagnetic field can be distorted near construction materials such as rebars. Therefore, this study conducted an experiment for identifying correction range of geomagnetic field near the construction material stocking area. It was analyzed that the geomagnetic field should be corrected up to 60cm in the horizontal direction from the stocking point if the height of stocking area for rebars is 40cm or more. This study can be used for important reference for development of geomagnetic field sequence-based indoor positioning technology suitable for construction sites.