• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2001년도 ICCAS
• /
• pp.92.2-92
• /
• 2001

This paper presents the time optimal reorientation solution of three-axis spacecraft which has only three magnetic torquers. It has been very difficult problem because the magnetic torquer generates only perpendicular to Earth magnetic field vector. In this paper, minimum-time solution using only magnetic torquer is solved using collocation method and nonlinear programming solver NPSOL. IGRF Earth magnetic field model used to simulate magnetic field. The result is verified by comparing to the result of numerical integration. The solution is obtained for the various reorientation maneuver of three axes rigid spacecraft. And the results show that all three axes of rigid spacecraft are controlled effectively only by magnetic torqure.

• 한국환경보건학회지
• /
• 제41권3호
• /
• pp.147-162
• /
• 2015

Objectives: The objective of this review was to summarize the primary role of three representative endocrine axes in aquatic vertebrates and discuss the effects on endocrine systems and their interactions in teleost fish after exposure to environmental contaminants. Methods: We summarized individual traits and mechanisms for hormonal and transcriptional interactions between the hypothalamic-pituitary-gonad (HPG), hypothalamic-pituitary-thyroid (HPT), and hypothalamic-pituitary-adrenal (HPA) axes in fish. We also provided a brief discussion on the effects of nonylphenol-induced toxicity on endocrine systems and their interactions in fish as a demonstration of holistic explanation. Results: Currently-available data showed that thyroid dysfunction is associated with reproductive toxicity due to changes in steroidogenic gene expressions and sex hormone levels as well as gonad glands in fish. As an example, we demonstrated that exposure to nonylphenol could induce estrogenicity in male fish by decreasing thyroid hormones, which contributes to increased aromatase expression. Although the mechanisms are complicated and involved in multiple ways, a number of studies have shown that sex steroids influence the HPT axis or the HPA axis in fish, indicating bi-directional crosstalk. Critically missing is information on the primary target or toxicity mechanisms of environmental contaminants among the three endocrine axes, so further studies are needed to explore those possibilities. Conclusions: This review highlights the interactions between the HPG, HPT, and HPA axes in fish in order to better understand how these endocrine systems could interact with each other in situations of exposure to endocrine disrupting chemicals.

• 보존과학회지
• /
• 제29권4호
• /
• pp.367-378
• /
• 2013

원삼국시대에 속하는 경기도 김포시 양촌유적에서 출토된 단조철부 5점과 주조철부 1점을 대상으로 미세조직 관찰과 비금속개재물 분석을 실시하였다. 단조품에 사용된 소재는 순철에 가까운 소재와 저탄소강이 사용되었고 성형 후 1점에만 담금질을 하였다. 주조품은 주철을 탈탄시킨 미세조직이 보여 주철탈탄 제강법이 적용된 것을 확인하였다. 비금속개재물 분석결과 철부는 고체저온환원법으로 제련하여 생산된 괴련철을 두드려서 제작하였다. FeO 함량이 $SiO_2$에 비해 비교적 높게 나타나 제련 시 노의 온도가 환원에 충분하지 못해 Fe의 회수율이 적었던 것으로 보이며 이 과정에서 광물에 포함된 K, P, Mg, Mn, Ti 등 불순물이 혼입되었다. Ca 함량이 높게 검출되는 곳이 있어 일부는 조제제로 석회물질을 넣었던 것으로 추정된다.

• 한국자기공명학회논문지
• /
• 제12권2호
• /
• pp.103-110
• /
• 2008

Spin Hamiltonian for the paramagnetic center with a three-fold symmetry and high spin ($S{\geq}2$) multiplicity should contain the fourth order zero-field splitting (ZFS) terms. Electron magnetic resonance transition lines of the center with S = 5/2 are expected to split in a pair when the magnetic field is applied off the principal axes of ZFS, while they are superimposed when the magnetic field is applied parallel to the principal axes of ZFS. In this study we report that the transition lines of $Mn^{2+}$ centers at the three-fold symmetric sites in $LiNbO_3$, chemically equivalent but physically different, split in two due to the nonzero fourth order ZFS term.

• 자원환경지질
• /
• 제16권2호
• /
• pp.111-123
• /
• 1983

The studied area is situated in tho southern part of the Ogcheon fold belt, where the "Ogcheon Group" is widespread with Jurassic and Cretaceous intrusions. The regional stratigraphy may be divided into three formations, the lower pebble bearing phyllitic, the middle dark grey phyllitic, and the upper black phyllitic formations. For the purposes of the present study, the area has been partitioned to three structural subareas based on major fold axes and fault line. The main subjects of the research have been discussed from two different points, multiple deformation and minor-micro fold styles. The former is analyzed by pebble elongation, folding and lineation in a pebbly formation as well as schistosity, crenulation cleavage and crenulated lineation in the phyllitic formation. The later describes the characteristic features of fold style in each formation and structural subarea. Although minor fold axes within broad pelitic rocks usually tend to trend northeast and to plunge northward, most of these were probably formed by two stages, first a similar fold phase and second a kink fold phase. Measured structural elements indicate that crenulation cleavage in phyllite formed parallel to fold axes of folded pebble followed a NE phase of first deformation and a fold axes of pebbles diagonal to bedding of phyllite are represented by a NW phase of a second deformation. Microscopically, quartz and mica grains form a micro fold enabling one to establish tectonic levels which occur in different deformation modes in each stratigraphic sequence. Microtextures such as crenulation cleavage, kink band, aggregate band of mica and pressure shadows of porphyroblast of quartz related to qarnet and staurolite may suggest the time relation of crystallization and tectonism. The result of this study may conform that three deformation phase, NE first phase-NE second phase-NW phase, occurred in the area.

• Strategy21
• /
• 통권44호
• /
• pp.142-176
• /
• 2018

So far, the main threat to South Korea was North Korea. That is why South Korea established a strategy based on the threat of North Korea and most of the budget on defense was used to deter North Korea. Even though the neighboring countries(China, Japan, and Russia) are growing as a real threat with abilities and intentions based on their powerful naval forces, South Korea has not yet been able to establish a strategy that regards neighboring countries as a threat. But the decades-old structural mechanism of the Korean security environment is undergoing a radical change on April 27, 2018, through the South-North summit and the Panmunjom Declaration. Under the changing security environment, South Korea was placed in a complicated dilemma that had to deal with threats of two axes(China), three axes(China, Japan), and four axes(Japan, Russia). If the one axis threat(North Korea) is dominated by land threats, the second, third and fourth axis threats are threats from the sea. This paper analyzed the maritime strategy of Korea within the framework of maritime-geopolitics, in other words recognition and expansion of the sphere of maritime. I have designed that the maritime defense space that we can deny from threats is divided into three lines of defense: 1 line (radius 3,000km), 2 lines (2,000km), and 3 lines (1,000km). The three defense zones of the three lines were defined as an active defense(1 line), defensive offense(2 line), active offense(3 line). The three defense zones of the three lines were defined as the sphere of core maritime, As a power to deny the sphere of core maritime, it was analyzed as a maneuvering unit, a nuclear-powered submarine, the establishment of missile strategy, and the fortification of islands station. The marine strategy of South Korea with these concepts and means was defined as 'Offensive Maritime Denial Strategy'.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 추계학술대회논문집
• /
• pp.1043-1047
• /
• 2003

Most of the measurement and the evaluation of hand-transmitted vibration have been performed by using a small size single axis accelerometer between the handle and the hand palm or a three axis accelerometer attached on an adapter outside the hand(indirect measurement). It is most desirable for the correct evaluation of hand-transmitted vibration form the power tool handle to measure the acceleration between the handle surface and the hand palm in the three axis(direct measurement) as recommended in ISO 5349-1. In the study three axes acceleration measurement device was developed of which the thickness was less than 7mm so that it can be placed between the handle and the palm without any inconvenience during the measurement. To verify the performance of the developed device, measured acceleration by the two methods, direct and indirect, were compared in the study.

• 한국반도체및디스플레이장비학회:학술대회논문집
• /
• 한국반도체및디스플레이장비학회 2003년도 추계학술대회 발표 논문집
• /
• pp.177-181
• /
• 2003

This paper presents a 3-axis fine positioning stage. All the procedure concerning the design and fabrication of the stage are described. The stage considered here is composed of flexure hinges, piezoelectric actuators and their peripherals. A special flexure hinge is adopted to be able to actuate the single stage in three axes at the same time. A ball contact mechanism is introduced into the piezoelectric actuator to avoid the cross talk among the axes. The final design is obtained with the theoretical analysis on the stage. An actual fine stage is developed and the design specifications are verified through an experiment.

• 한국산업융합학회 논문집
• /
• 제21권4호
• /
• pp.183-189
• /
• 2018

The focus of this paper is to design and control a three fingered hand system with eight axes for smart factory with an flexible controller, and to keep a useful big database for dynamic manipulation based on the experimental results. The weight of the hand module is only 1.2 kg, but flexible motion and powerful grasping are possible. To achieve such a flexible motion control of a robotic hand, we have developed a robust and precise fingered hand with a control system incorporating image recognition system in which we deal with the problems of not only accuracy and range of motion but also the flexibility of hand. The fingers are arranged so as to grasp both circular and prismatic objects. In order to achieve the light mechanism, we reduced the number of joints and fingers as much as possible. In this study, it was used three fingers with eight axes which is the optimal number to achieve a robust grasping diverse shape parts for smart factory.

• Journal of Astronomy and Space Sciences
• /
• 제29권4호
• /
• pp.389-395
• /
• 2012

The problem of spacecraft attitude control is solved using an adaptive neuro-fuzzy inference system (ANFIS). An ANFIS produces a control signal for one of the three axes of a spacecraft's body frame, so in total three ANFISs are constructed for 3-axis attitude control. The fuzzy inference system of the ANFIS is initialized using a subtractive clustering method. The ANFIS is trained by a hybrid learning algorithm using the data obtained from attitude control simulations using state-dependent Riccati equation controller. The training data set for each axis is composed of state errors for 3 axes (roll, pitch, and yaw) and a control signal for one of the 3 axes. The stability region of the ANFIS controller is estimated numerically based on Lyapunov stability theory using a numerical method to calculate Jacobian matrix. To measure the performance of the ANFIS controller, root mean square error and correlation factor are used as performance indicators. The performance is tested on two ANFIS controllers trained in different conditions. The test results show that the performance indicators are proper in the sense that the ANFIS controller with the larger stability region provides better performance according to the performance indicators.