• Journal of Magnetics
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• 제18권4호
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• pp.454-459
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• 2013

This paper deals with an optimal angle error reduction method of magnetic position sensor using hall effect elements. The angle detection simulation for the magnetic position sensor is performed by 3 dimensional finite element method and Taguchi method, one of the design of experiments. The magnetic position sensor is required to generate ideal sine and cosine waveforms from its hall effect elements according to rotation angle for precise angle information. However, the output signals are easy to include harmonics due to uneven magnetic field distribution from permanent magnet in the air-gap in the vicinity of hall effect elements. For the Taguchi method, three design parameters related to position of hall effect elements and shape of back yoke are selected. The characteristics of optimal magnetic position sensor are compared with those of original one in terms of simulation as well as experiment. Finally, the performances of the motor adopting original model and optimal model are represented for the purpose of verification of motor performance due to signals from magnetic position sensor.

• Journal of the korean society of oceanography
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• 제38권1호
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• pp.17-23
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• 2003

We report the distribution of $^{210}$ Pb and various metallic elements (Al, Fe, Mg, Ca, Ti, Mn, Sr, Ba, Zn, V, Cr, Zr, Ni, Cu, and Y) in the sediment cores from six shellfish-farming bays in the South Sea of Korea. The $^{210Pb}$ inventories in Deukryang, Gwangyang, and Goseong Bay cores were comparable to those expected from the known fallout input. However, the $^{210}$ Pb inventories were two times higher in Jinju, Gangjin, and Hansan-Koeje Bay cores, suggesting an important role of other sources such as fluvial inputs. Based on the enrichment factor analyses, non-detrital fractions of all the measured elements were found to be insignificant. The Mn was highly enriched only in the surface sediments of the Jinju and Goseong Bay, which implies that the surface-sediment environment of these bays is efficiently oxidizing Mn remobilized from either pore waters or bottom seawaters. These data set provides the sources of heavy metal in sediment around shellfish farms and the current level of metallic elements for the future monitoring.

• KSTLE International Journal
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• 제10권1_2호
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• pp.17-22
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• 2009

The numerical analysis of elastohydrodynamic lubrication for the ball and roller bearings is performed in order to study the effect of the number of rolling elements and the shaft load on the minimum film thickness. A finite difference method and the Newton-Raphson method are used in the analysis. For a given shaft load, the maximum load of rolling element is determined along with the number of rolling elements. And then the minimum film thickness is calculated for several rolling bearings. The shape of film thickness and the pressure distribution are also studied.

• 유통과학연구
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• 제17권12호
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• pp.81-93
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• 2019

Purpose: The success of electronic commerce businesses is the ability to retain the customers and inspire their loyalty in online shopping. The purpose of this study is to develop a model to study the effect of perceived mental benefits, online trust, and hedonic value on the elements of electronic loyalty. Research design, data and methodology: Mixed research method was applied in this study with qualitative and quantitative research method. Qualitative data was collected through focus group discussion with electronic commerce experts. Quantitative data was collected through a survey of 917 customers, in which conducted in four cities and one province in Vietnam. SmartPLS software is used for processing quantitative data. Results: The study points out that four constructs of the mental benefit concept, although not entirely, have an impact on online trust and hedonic value. At the same time, two antecedents of electronic loyalty's three elements are online trust and hedonic value. Conclusions: Through the positive influence between the elements in the conceptual model, the study has shown that the perceived mental benefits, online trust, and hedonic value are important factors to shape the electronic loyalty in developing countries, such as Vietnam. This study proposed some scientific and managerial implications.

• Steel and Composite Structures
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• 제18권5호
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• pp.1103-1117
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• 2015

It is known that material properties, connection quality and manufacturing methods are among the important factors directly affecting the behavior of steel connections and hence steel structures. The possible performance differences between a fabricated connection and its computer model may cause critical design problems for steel structures. Achieving a reliable design depends, however, on how accurately the material properties and relevant constitutive models are considered to characterize the behavior of structures. Conventionally, the stress and strain fields in structural steel connections are calculated using the finite elements method with assumed material properties and constitutive models. Because the conventional strain gages allow the measurement of deformation only at one point and direction for specific time duration, it is not possible to determine the general characteristics of stress-strain distributions in connections after the laboratory performance tests. In this study, a new method is introduced to measure displacement distribution of simple steel welded connections under tension tests. The method is based on analyzing digital images of connection specimens taken periodically during the laboratory tension test. By using this method, displacement distribution of steel connections can be calculated with an acceptable precision for the tested connections. Calculated displacements based on the digital image correlation method are compared with those calculated using the finite elements method.

• 자원환경지질
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• 제54권3호
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• pp.331-352
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• 2021

The relationship of both heavy metals and major elements in soil, plants, and groundwater was studied in a hyper-arid area and depends completely on the groundwater to cover its all needs. The study reviles that 27.3% of the studied groundwater was strongly acidic and has very low pH values (

• 한국수학교육학회지시리즈C:초등수학교육
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• 제18권3호
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• pp.235-247
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• 2015

본 연구에서는 2009 개정 초등수학 3~4학년군 교과서에 포함된 STEAM 요소를 학년별, 내용 영역별로 분석하여 어떤 요소가 어떻게 분포되어 있는지를 알아보고자 하였다. 연구 결과 STEAM 요소의 학년별 분포는 4학년 1학기 184개(27.7%), 3학년 2학기 164개(24.8%), 3학년 1학기 162개(24.4%), 4학년 2학기 153개(23.1%)의 순으로 나타났고, 3학년과 4학년의 차이는 거의 없다고 볼 수 있다. 내용 영역별 분포는 STEAM 요소가 내용 영역의 분포 비율과 비슷하게 분포되어 있음을 알 수 있었다. 그러나 STEAM 요소별로는 편차가 심하다는 것을 알 수 있었다. 예술(A) 요소가 448개(67.6%)로 가장 많았는데, 표현예술이 344개(51.9%)로 문화예술의 104개(15.7%)보다 3배 정도 많았다. 표현예술이 약 절반을 차지하고 있는 것은 하위요소로 수학 교과서에 만화, 글쓰기, 이야기 만들기 등의 의사소통 요소가 많이 포함된 것이 주된 이유라고 볼 수 있다. 다음으로 기술공학(T-E) 요소가 160개(24.1%) 포함되었고, 과학(S) 요소가 55개(8.3%)가 포함되어 있었다. 다음 교육과정의 교과서 개발 시 상대적으로 적은 과학 요소도 보다 적극적으로 융합하려는 노력을 기울일 필요가 있다.

• 한국환경과학회지
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• 제16권1호
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• pp.21-26
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• 2007

The concentrations of fourteen mineral and trace elements (Al, Ca, Fe, K, Mg, Se, Ba, Co, Cu, V, Pb, Hg, Cd and As) were determined in Ganoderma Lucidum and their infusions consumed for medical purposes collected from Vietnam, China and some places in Korea. Concentrated acid digestion procedure was applied under optimized conditions for dissolution of these medicinal fungi. Element concentrations in these fungi and their in-fusions were then determined by ICP-AES. The mineral and trace element content of these samples and their in-fusions showed a wide variability However, distribution of some elements in the infusions is not high.

• Journal of Applied Biological Chemistry
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• 제60권3호
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• pp.207-211
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• 2017

It is introduced an outstanding book about an important topic in occupational and environmental sciences i.e., the opportunities and challenges that may be connected with increasing the use and distribution of rare earth elements. These chemically similar elements, comprising the lanthanides, scandium, and yttrium, are involved in a number of essential technological applications, and their effects raise a number of human health issues of relevance to the occupational and environmental sciences. The book that I introduced here, "Rare Earth Elements in Human and Environmental Health; At the Crossroads between Toxicity and Safety" edited by Giovanni Pagano (Pan Stanford Publishing Pte. Ltd., Temasek Boulevard, Singapore) represents a break from that situation. It is essential to increase our knowledge about the environmental fate and biological effects of these technologically important metals in order to prevent unforeseen long-term man-made consequences to human health. This book is likely to become an important resource for scientists, engineers, and decision makers who understand the need for sensible exploitation of this resource.

• 한국지구과학회지
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• 제34권4호
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• pp.289-302
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• 2013

대부분 니질 퇴적물로 구성된 황해 남동부 흑산니질대 퇴적물의 기원지를 밝히기 위해 퇴적물 시료에 대해 주성분 원소와 희토류 원소(REE)를 분석하였다. 표층 퇴적물 시료는 흑산니질대 내 51지점에서 피스톤식과 박스형 시료 채취기로 획득하였다. 흑산니질대의 표층퇴적물은 니 퇴적물이 우세하게 나타나며, 평균입도는 $5-6{\phi}$이다. 공간적으로 북쪽지역은 실트함량이 높고, 남쪽지역으로 갈수록 점토함량이 증가한다. 흥미롭게도 주성분 원소와 희토류 원소 함량 특성은 퇴적물 기원 해석에 있어 다른 결과를 가져왔다. Fe/Al과 Mg/Al 함량 비, $Al_2O_3$와 MgO 함량 비, $Al_2O_3$와 $K_2O$를 각각 도시한 결과, 흑산니질대 퇴적물은 한국 기원의 퇴적물이 우세한 것으로 나타났다. 하지만 희토류 원소의 특성은 중국 기원의 퇴적물이 우세함을 반영한다. 이러한 기원 불일치는 각 원소의 함량 조절요인이 다르기 때문이다. 주성분 원소는 입도와 높은 상관관계를 고려할 때 입도에 따라 그 함량이 영향을 받는 것으로 해석된다. 반면에 희토류 원소는 입도와는 상관관계가 낮으며, 중광물 함량에 의해 조절되는 것으로 사료된다. 이와 같이, 각기 다른 추적자에 따른 기원의 불일치를 해결하기 위해 추가적인 연구가 필요하다.