• 농업과학연구
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• 제39권4호
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• pp.459-466
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• 2012

The objective of this study is to observe growth pattern of grand rapids(lettuce) according to different dexperimental conditions for minimizing its growth period such as composition of nutrient, irradiation time of light source and cultivation mode. The culture of water spray type using seeds of grand rapids was performed during growth period of total 50 days. Experimental conditions consist of five compositions of nutrient (PW 0.5 mS/cm, PW 1.0 mS/cm, PY 0.5 mS/cm, PY 1.0 mS/cm, PW 2.0 mS/cm) and three irradiation times of light source (12h(on) / 12h(off), 18h(on) / 06h(off), 24h(on) / 00h(off)). Illumination was adjusted to ratio of 7:1:1 of red, blue and white color, respectively. Indoor environmental condition for cultivating grand rapids is as follows: temperature (19-$22^{\circ}C$), relative humidity (60-70%) and carbon dioxide (1,000-1,200 ppm). The data were obtained from five iteration tests. The maximum growth level was observed in the experimental condition of 18 hr(on) / 06 hr(off) and PY 1 mS/cm for 1st week of cultivation period, 24 hr(on) / 00 hr(off) and PY 1mS/cm for 2nd week of cultivation period, and 24 hr(on) / 00hr(off) and PW 1 mS/cm for 3rd week of cultivation period, respectively. On the contrary, the minimum growth level was observed in the experimental condition of 18 hr(on) / 06 hr(off) and PW 0.5 mS/cm for 1st week of cultivation period, 12 hr(on) / 12 hr(off) and PW 0.5 mS/cm for 2nd week of cultivation period, and 12 hr(on) / 12 hr(off) and PY 0.5 mS/cm for 3rd week of cultivation period, respectively. Based on the results obtained from this study, it is concluded that the growth level of grand rapids varied with different irradiation time of light source and composition ratio of nutrient according to cultivation period.

• 한국사회복지학
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• 제43권
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• pp.328-357
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• 2000

From Foucault's Perspective of power, this study is trying to illuminate the characteristics and limitations of 'empowerment' which is widely accepted as a central value and practice skill of social work. Notwithstanding the superficial consensus on the empowerment, the author shows that it is a confusing concept with contrasting expectations and conflicting methodologies or only a wishful rhetorical jargon. Furthermore, he argues that the empowerment is not just a value-free intervention skill working outside the ruling power but a ruling-discourse or power-mechanism of a liberal society which makes citizens responsible voluntarily. For a theoretical background for these arguments, the 2nd chapter reviews Foucault's theory of power. The 1st part of the 3rd chapter summarizes the historical background of empowerment practice and its methodological characteristics and meanings, the 2nd part reviews the existing critics on the conceptual and practical limitations of empowerment, and the last part reveals, based upon Foucault's theory of power, that the empowerment is a typical mode of ruling power in liberal societies. The author expects that this study may warn the moral and intellectual superiority complex of social work discourse and help stimulate the ethical sensibility and responsibility in social work practice.

• 한국유체기계학회 논문집
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• 제15권2호
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• pp.12-19
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• 2012

This study presents unsteady and unstable characteristics of three stage transonic axial compressor, developed by Korea Aerospace Research Institute. As approaching to the unstable operating region at the 103% design speed of the compressor, a modal type stall precursor appears in front of highly loaded 3rd rotor row at first, and it propagates to the upstream. On the contrary, actual stall cell initiates from the stall precursor in front of the 1st rotor row, and it propagates to the downstream of the compressor. After the stall region reached the 3rd stage and stall cell rotates circumferentially about 360 deg, it develops to one dimensional compressor surge mode. It shows a mild surge behaviour with 3~4 Hz frequency. From the test data, it can be suggested that there is a priority to give an optimum blade loading distributions to construct a multi stage transonic axial compressor stages either to secure more stable compressor operating ranges, or to maximize the compressor efficiency.

• 한국의상디자인학회지
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• 제8권2호
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• pp.95-108
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• 2006

The purpose of this study was to analyze the historical change of Paris Collection in relation to the social and cultural environment. Together with the various changes in society, creates fashion, the historical background of the Paris Collections is analyzed from the end of the 19th century until the present. The research method includes analysis entered on data from literature and magazines. From this study, the following conclusions can be reached. 1. Paris Collection is composed of various situations such as the economic aspect, the changing society, the change of the costumes, the change of consumer's consciousness, etc,. 2. The position and role of Paris Collection will be changed in the future. But, there is no alternative. Paris Collection is the best system which we need in our society. 3. Since the level of the planning of the apparel industry becoming raised rapidly, Paris collection tend to avoid the traditional aspect. 4. In order to make good product, good understanding of the historical background need. It must be considered to understand changes such as consumers lifestyles, social trend, etc.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.527-535
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• 2012

This paper reports the active vibration control of plates using positive position feedback controller (PPF). The equations of motion of the plate under force and moment pairs were derived and the equations of PPF controllers were formulated. The effect of the parameters - gain and damping ratio - of the PPF controllers on the open loop transfer function was investigated mainly in terms of the system stability. Increasing the gain of the PPF controller tuned at a mode, the magnitude of the open loop transfer function is increased at all frequencies without changing the phase behavior. The increase of the damping ratio of the PPF controller leads to decrease the magnitude of the open loop transfer function and to modify its phase characteristics to be more stable. Two PPF controllers connected in parallel, Each PPF controller is tuned at the $1^{st}$ and $2^{nd}$ modes, respectively. Their parameters were determined to remain the system to be stable based on the results of the parametric study. A significant reduction in vibration at the 2 modes can be obtained.

• 한국소음진동공학회논문집
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• 제16권2호
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• pp.183-189
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• 2006

In mobile phones of multimedia era, microspeakers of high qualify sound are essential parts to generate human voice in speaker phone and MP3 song player. In this paper, two types of microspeakers, outer permanent magnet (PM) and combined PM type, are analyzed using electromagnetic, mechanical and their coupling analysis. For performance comparison, voice coil diameter is chosen as a design parameter to change excitation position and magnet volume for both types. For combined PM type, sound pressure level (SPL) is improved due to increased PM volume compared to outer PM type. Also, with the decreased voice coil diameter for combined PM type, the 1st resonant mode of the diaphragm is more efficiently excited due to concentrative excitation, resulting in lower and broader frequency range. Therefore, it can be said that the combined PM type microspeakers are more advantageous for high performance microspeaker which are essential for multimedia era.

• 터널과지하공간
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• 제8권2호
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• pp.118-129
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• 1998

A three dimensional boundary element method-BEAP3D was applied to the stability analysis of the mine openings not only to improve the stability during mining operations but also to serve the evaluation of the mine openings for further utilization. Stability analysis on the stability of the room-and-pillar stopes underneath of the old mine openings and the openings to be created by the newly proposed sublevel stoping method at the Nowhado Pyrophyllite Mine, showed that rock mass around the old and new stopes would be stable. Six stopes of a sublevel stoping designed for the Choongmu Limestone Quarry would be stable, too. A sublevel stoping method consisting of six stopes was similarly suggested for the Keumpyung Quartzite Mine. The stability can be guaranteed through out six stopes. Since mining starts from the bottom 1st sublevel to the uppermost sublevel, the safety of the stopes will improve together with the mining process. It would highly be recommended to investigate in-situ rock properties and the rock stresses for future studies. Even though the rock around the uppermost part and bottom of all the stopes have a very high factor of safety, spot reinforcements such as rock bolting would be recommended to mitigate the intermediate and minor principal stresses acting in a tensile mode.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.75-78
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• 2014

MLCC is one of the most frequently used component in high-tech device like smart phone. Because of dynamic characteristic of piezoelectric materials which is main ingredient of MLCC, its vibration leads to acoustic noise from pcb. To solve this problem at minimal cost, company has to change only the main noise-generating MLCC to low noise-generating MLCC. To find the main noise source, this study approached to solution from a vibration point of view. From mode shapes of pcb at particular frequencies, two groups can be obtained; MLCCs soldered at where maximum deformation occurs and where anti-phase with respect to the other group appears. When the MLCC belongs to 1st group does not working, amplitude at where maximum deformation occurs decreases compared to when all MLCCs are working. This tendency also appears in noise measurement. This analysis can be put to use in various fields where require noise reduction or noise source identification.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.197-202
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• 2014

Floor Impact Noise is a structure-borne noise which is mainly caused by vibration of concrete slabs. The majority of previous studies have focused on investigating performance of absorbing sheets on the reduction of floor impact noise. But absorbing sheets do not efficiently reduce heavy-weight floor impact noise level because it cannot absorb slab vibration, which is the fundamental noise source. In this study, double-floor system was developed in order to reduce floor impact noise level in residual buildings. This floor system reduces heavy-weight impact noise level by reducing vibration response at the center of slab, which has maximum amplitude in the 1st vibration mode. In order to identify the performance of the double-floor system, experiments were planned. Primary test parameters are span of double floor, arrangement and types of absorbing sheets.

• 한국기계가공학회지
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• 제8권3호
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• pp.27-32
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• 2009

In this study, static and dynamic stability estimations on the diecutter with finite element modelling were carried out to be creased and cut away printed sheet exactly. To cut away the sheet exactly, the large force should be pressured on diecutter. And which affects not only the quality of produced sheets but also the stability of diecutter. The analyses with and without the tare of diecutter were carried out with NASTRAN software on applying 400 ton force to its top and moving table respectively. It was known that maximum von-Mises stress of 221 Mpa in diecutter was occurred at the toggle, and it was smaller than the yield stress of 280 Mpa. And maximum deformation of 0.75 mm was occurred at the top table. The natural frequencies of 41, 102, 108, 115, and 134 Hz for the 1st, 2nd, 3rd, 4th and 5th mode, which had been determined by numerical simulation, were not coincided with the max. speeds of motor and moving table of 29 and 2 Hz. And which was verified by vibration test. Therefore it may be estimated that the structure of the diecutter is statically and dynamically stable.