• Environmental Analysis Health and Toxicology
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• 제15권3호
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• pp.99-106
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• 2000

Ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) are various applied as chelating agents for metal ions, then they are widely used in many industrial processes and domestic products. A method is described for the determination of EDTA and NTA in water samples by GC/MS . The reaction temperature, reaction time and pH for esterification of EDTA and NTA were investigated using 10% sulfuric acid-methanol, ethanol and propanol. Optimum conditions were obtained by the esterification in 80$\^{C}$ for 1hr with ethanol. Method detection limits of ethylated EDTA and NTA in the 200 ml of water samples were 0.05 ng/ml, respectively, EDTA and NTA could be determined in the range of 0.05∼23.6 and 0.05∼7.0 ng/ml in treated water, and in the range of 0.06∼25.0 and 0.05∼6.40 ng/ml in raw water respectively. Risk assessments with EDTA and NTA exposure by drinking water ingestion were carried out. Based on the results of analysis, chronic daily intakes of EDTA and NTA would be less than the value of acceptable daily intake or tolerable daily intake.

• 한국운동역학회지
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• 제16권4호
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• pp.147-152
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• 2006

The purpose of this study was to develop the experimental machine for the putting strokes. This experimental machine is called Pendulum Putting Machine(PPM). The height of PPM is 75cm and the mass is 10kg. To make the frame of this machine, 24 and 20 diameters of iron pipes were used. Bottom of the frame(bottom girdle) was made with circle shape and top of the frame(top girdle) was made with rectangular shape. Above the top girdle, iron plate($12{\times}17{\times}0.5cm$) was placed to connect the ball bearing. At the top of the frame two ball bearings with axis were placed for the diverse lies of putters and irons. To verify usefulness of this machine, experiments were executed with the PPM. Two major experimental conditions were hitting points(sweet spot, toe side, heel side) and hitting places(bottom, 3cm before bottom, 3cm after bottom). Eleven different cases were tested. The results showed that the diversity of the ball placement(distance and direction) was acceptable(distance range, 2.70-5.87 standard deviation; direction range, 1.71-4.65 standard deviation). Overall the Pendulum Putting Machine is very useful for the study of putting and driving strokes.

• Macromolecular Research
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• 제10권2호
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• pp.103-107
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• 2002

High purity water soluble chitosans (WsCs) were employed as a flocculant to remove heavy metal ions from wastewater of industrial plating wastewater treatment complex. Their weight average molecular weights and polydispersities were 272,000~620,000 g/mol and 1.4~1.9 range, respectively and were readily soluble in water in the pH range of 3~11. Heavy metal ions such as chromium, iron and copper were removed well by WsCs. When WsCs was blended with either sodium N, N-diethyldithiocarbamate trihydrate (SDDC$_{T}$) or sodium salicylate (SSc), the removal efficiency was further increased primarily due to the excess amount of hydrophilic sulfonic and carboxylic groups. Especially, in the case of WsCs-SSc the remaining chromium and copper concentrations were 0.1 mg/L and 9.5 mg/L, which are 1/15 and 1/3 compared with that of pure WsCs, respectively. The former is within the acceptable limit, but the latter is not. Therefore, the effective copper flocculant remains to be studied.d.

• 제어로봇시스템학회논문지
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• 제17권2호
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• pp.149-156
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• 2011

This paper reveals a distance estimation algorithm based on multi-code ultrasonic and wireless sensor network. For measuring the distances among the sensor nodes, each ultrasonic transmitter transmits multi-code ultrasonic signal simultaneously. Receivers use cross correlation method to separate the coded signals. The information of measured distances is broadcasted to each sensor node by wireless sensor network. The wireless sensor network measures the distance among the sensor nodes using the received signal strength of the broadcasting. The multi-code ultrasonic have a limitation of measurable distance. And the received signal strength is affected from an environment. This paper measures a distance using ultrasonic and a received signal strength in short range. These measured data are applied to the least square estimation algorithm. By the expansion of the fitting curve, a distance measurement in long range using the received signal strength is compensated. The coupled system reduce the error to an acceptable level.

• IEIE Transactions on Smart Processing and Computing
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• 제5권2호
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• pp.107-116
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• 2016

Premature babies of less than 37 weeks gestation might require oxygen therapy as an integral part of treatment and respiratory support. Because of their under-developed lungs, these so-called "preemies" might contract respiratory distress syndrome (RDS). To treat RDS, neonatal oxygen therapy is administered, where controlled oxygen gas is measured as a fraction of inspired oxygen ($FiO_2$). However, exposure to high oxygen content during long treatment could cause oxygen intoxication, which might cause permanent blindness due to retinopathy of prematurity (ROP), whereas insufficient oxygen exposure could cause severe hypoxia. A doctor would use oxygen saturation ($SpO_2$) data and prescribe a dose of $FiO_2$ to maintain $SpO_2$ within a suitable range. One objective is to maintain $SpO_2$ within the acceptable range using $FiO_2$ that is as low as possible. Adjustment of $FiO_2$ would normally be done by nurses every 15 to 30 minutes, which might not be safe in many situations. An error in $FiO_2$ adjustment during a manual procedure could be as large as +/- 2.5%. This paper presents a system that can determine an $FiO_2$ value suitable to the current $SpO_2$ and that automatically adjusts $FiO_2$ with an error clearance of +/- 0.25%.

• 한국실내디자인학회논문집
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• 제18권4호
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• pp.43-50
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• 2009

Design trend, transparency, which has been developed under a reflection of current periodic environment, has been exposed to people all over the world through varieties of architecture facade and interior space. As interior space follows this trend, which has difference in showing space from the past, transparency becomes an important measure of showing openness of certain space. Main objective of this research is to understand a characteristics of materials that leads transparency a important measure to the modern interior design, and this will set the range to this applicable materials for appropriate areas of defining transparency in an interior. Characteristic uses of transparent materials found in this research which leads transparency into interior space are described below: First, there are two perspectives in transparency. One is visibility and material wised transparency and the other is conditional and spacial wised transparency. With this knowledge, we can expand a level of transparency with ideas such as clarity, opacity, visible transmission, and reflection, and this broadened range will vary the acceptable materials used to show transparency. Second, transparent materials are used with many different purposes in modern interior space as furnitures, sanitary fixtures, partitions, and other structures. With using modern technology in reforming this materials brought new methods in structure composing. last, transparent materials' expnt pable characteristics made modern interior space to have a control over spacial homogeneity, a simplified octlines, weakened boundaries, and compositional effects by interference and vision.

• 한국환경독성학회:학술대회논문집
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• 한국환경독성학회 2003년도 추계국제학술대회
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• pp.158-158
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• 2003

Bioassays using gametes of sea urchins are widely used in ecotoxicological assessments of marine environments. Since most of sea urchin species in Korean coastal water spawn from spring to autumn, bioassay with them during the winter is impossible. In the course of developing standard methods for bioassays with Korean species, we found a winter-spawning starfish, Asterias amurensis, Since reproductive mode of asteroids is similar to echinoids, the bioassay protocol for sea urchins could be applied similarly to the starfish. Here, we tested and determined several conditions for the acceptability of bioassay with A. amurensis. The least required time for formation of fertilization membrane of fertilized eggs to be easily distinguished from unfertilized ones was 60 min. The threshold of sperm to egg ratio that could make acceptable fertilization rates in controls was 3000. The allowed time for manipulation of sperm after dilution in seawater was at most 3 hr. The optimal exposure time of sperms when the response against toxicant solution was relatively stable was in the range of 20-60 min. The tolerance range of sperms to the salinity of test solution was 26-38 psu. The sensitivity of A. amurensis sperm was intermediate among marine organisms commonly used in aquatic toxicity tests. The sperm bioassay with A. amurensis can be satisfactorily applied to toxicity assessments of marine environments.

• International Journal of Aeronautical and Space Sciences
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• 제16권3호
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• pp.463-474
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• 2015

Future Ground Control Stations (GCSs) for Unmanned Aerial Vehicles (UAVs) teleoperation targets better situational awareness by providing extra motion cues to stimulate the vestibular system. This paper proposes a new virtual environment for long range Unmanned Aerial Vehicle (UAV) control via Non-Line-of-Sight (NLoS) communications, which is based on motion platforms. It generates motion cues for the teleoperator for extra sensory stimulation to enhance the guidance performance. The proposed environment employs the distributed component simulation over GSM network as a simulation platform. GSM communications are utilized as a multi-hop communication network, which is similar to global satellite communications. It considers a UAV mathematical model and wind turbulence effects to simulate a realistic UAV dynamics. Moreover, the proposed virtual environment simulates a Multiple Axis Rotating Device (MARD) as Human Machine Interface (HMI) device to provide a complete delay analysis. The demonstrated measurements cover Graphical User Interface (GUI) capabilities, NLoS GSM communications delay, MARD performance, and different software workload. The proposed virtual environment succeeded to provide visual and vestibular feedbacks for teleoperators via GSM networks. The overall system performance is acceptable relative to other Line-of-Sight (LoS) systems, which promises a good potential for future long range, medium altitude UAV teleoperation researches.

• 한국항공우주학회지
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• 제33권1호
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• pp.33-38
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• 2005

로터 블레이드 가진 주파수에서의 가진력이 헬리콥터 진동의 주요 요인이다. 이 로터 블레이드 가진 주파수는 일반적으로 10~30 Hz 영역이고 관심 기체 모드들도 이와 유사하다. 그런데 해외 제작 헬리콥터 전방 끝단에 무거운 센서를 장착하는 것은 기체의 동적 특성 변화를 가져와 로터 가진 주파수와 공진을 유발할 수 있다. 전 기체의 동적 특성에 변화를 유발하지 않도록 하기 위해, 무거운 센서를 어떻게 장착할 것인지를 개념적 접근 및 유한요소 해석을 통해 결정하였다. 센서 마운트 시스템이 장착된 전 기체의 지상 진동시험 결과는 장착 설계가 타당함을 보여준다.

• Journal of Welding and Joining
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• 제32권2호
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• pp.70-75
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• 2014

In automotive industry, applying of Mg alloy to autobody has been issued recently as a light metal. But poor resistance spot weldability of Mg alloy is blocking commercialization. So studies on improving resistance spot weldability of Mg alloy is increasing continuously. For reduce loss of heat input during welding, inverter DC power source is considered because of short rise time to target welding current. But rapid rising of welding current can increase temperature rapidly in nugget and oxide film between electrode and base metal, and that causes generating expulsion on low welding current range. In this study, for increase optimum welding current range and prevent generating expulsion, applicate various types of welding current waveform controls during resistance spot welding. For analysis effects of each current waveform control, acceptable welding current regions according to electrode force and welding time is determined and lobe diagram is derived. In result, pre heat is proposed as optimum type of welding current waveform control.