• Structural Engineering and Mechanics
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• 제70권5호
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• pp.551-562
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• 2019

In the present study, a suitable mathematical model considering parabolic transverse shear strains for dynamic analysis of laminated composite skew plates under different types of impulse and spatial loads was presented for the first time. The proposed mathematical model satisfies zero transverse shear strain at the top and bottom of the plate. On the basis of the cubic variation of thickness coordinate in in-plane displacement fields of the present mathematical model, a 2D finite element (FE) model was developed including skew transformations in the mathematical model. No shear correction factor is required in the present formulation and damping effect was also incorporated. This is the first FE implementation considering a cubic variation of thickness coordinate in in-plane displacement fields including skew transformations to solve the forced vibration problem of composite skew plates. The effect of transverse shear and rotary inertia was incorporated in the present model. The Newmark-${\beta}$ scheme was adapted to perform time integration from step to step. The $C^0$ FE formulation was implemented to overcome the problem of $C^1$ continuity associated with the cubic variation of thickness coordinate in in-plane displacement fields. The numerical studies showed that the present 2D FE model predicts the result close to the analytical results. Many new results varying different parameter such as skew angles, boundary conditions, etc. were presented.

• Wind and Structures
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• 제15권6호
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• pp.481-494
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• 2012

The greenhouse type metal structures are increasingly used in modern construction of livestock farms because they are less laborious to construct and they provide a more favorable microclimate for the growth of animals compared to conventional livestock structures. A key stress factor for metal structures is the wind. The external pressure coefficient ($c_{pe}$) is used for the calculation of the wind effect on the structures. A high pressure coefficient value leads to an increase of the construction weight and subsequently to an increase in the construction cost. The EC1 in conjunction with EN 13031-1:2001, which is specialized for greenhouses, gives values for this coefficient. This value must satisfy two requirements: the safety of the structure and a reduced construction cost. In this paper, the Navier - Stokes and continuity equations are solved numerically with the finite element method (Galerkin Method) in order to simulate the two dimensional, incompressible, viscous air flow over the vaulted roofs of single span and twin-span with eaves livestock greenhouses' structures, with a height of 4.5 meters and with length of span of 9.6 and 14 m. The simulation was carried out in a wind tunnel. The numerical results of pressure coefficients, as well as, the distribution of them are presented and compared with data from Eurocodes for wind actions (EC1, EN 13031-1:2001). The results of the numerical experiment were close to the values given by the Eurocodes mainly on the leeward area of the roof while on the windward area a further segmentation is suggested.

• 한국수산과학회지
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• 제32권3호
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• pp.266-270
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• 1999

성숙 점농어 뇌에서 세 종류의 생식소자극호르몬 분비호르몬 (GnRH)의 소재를 면역조직화학법에 의해 동정하였다. sGnRH 양성 신경세포체는 후각망울, 복측 종뇌와 전시각 지역에 분포하였다. 양성 신경섬유는 후각망울에서부터 척수에 이르기까지 다양하게 분포하였다. 면역신경섬유는 뇌의 전지역인 후각망울, 종뇌, 시각시개, 소뇌, 연수 그리고 머리쪽 척수에서 발견되었다. 대부분의 경우 이들은 모두 다발을 형성하지는 않았다. 그러나 후각망울에서 뇌하수체로 뻗어있는 양성 신경섬유는 가장 뚜렷하였다. cGnRH-II 양성 신경세포체는 후엽에서 발견되었다. 그러나 cGnRH-II 면역신경섬유도 후각망울에서 뇌하수체로 뻗은 면역신경섬유를 제외하고는 기본적으로 sGnRH 양성 신경섬유와 분포가 유사했다. 이것은 점농어 뇌에서 sGnRH와 cGnRH-II가 알려진 내인성 펩타이드이며, 이들이 다양한 신경내분비 기능을 수행할 것이라는 점을 의미한다. sGnRH는 GTH의 분비를 조절 할 뿐만 아니라 신경전달조절자로서, cGnRH-II는 단지 신경전달조절자로서 작용할 것으로 생각된다.

• 한국정밀공학회지
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• 제27권11호
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• pp.98-105
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• 2010

In this paper, double ball-bar is used to estimate the geometric errors of a rotary table, which includes one-axial motion, two-radial motions and two-tilt motions, except the angular positioning error. To simplify the measurement procedures, three measurement steps have been designed and developed. At each measurement step, one end of the double ball-bar is fixed at the nose of spindle and the other end is located on the rotary table. And specific circular test path is planned to keep the distance between two balls as constant at ideal case. The relationship including the geometric errors of a rotary table and the measured distance between two balls which is distorted by the geometric errors is defined by using ball-bar equation. Each geometric error is modeled as $4^{th}$ order polynomial considering $C^1$-continuity. Finally the coefficients of polynomial are calculated by least-square method. Simulation is done to check the validation of the suggested method considering set-up errors and measurement noise. Suggested method is applied to estimate geometric errors of a rotary table of a 5-axis machine tool.

• 로봇학회논문지
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• 제15권1호
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• pp.8-15
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• 2020

This research is a case study of underwater object tracking based on real-time recurrent regression networks (Re³). Re³ has the concept of generic object tracking. Because of these characteristics, it is very effective to apply this model to unclear underwater sonar images. The model also an pursues object tracking method, thus it solves the problem of calculating load that may be limited when object detection models are used, unlike the tracking models. The model is also highly intuitive, so it has excellent continuity of tracking even if the object being tracked temporarily becomes partially occluded or faded. There are 4 types of the dataset using multi-beam sonar images: including (a) dummy object floated at the testbed; (b) dummy object settled at the bottom of the sea; (c) tire object settled at the bottom of the testbed; (d) multi-objects settled at the bottom of the testbed. For this study, the experiments were conducted to obtain underwater sonar images from the sea and underwater testbed, and the validity of using noisy underwater sonar images was tested to be able to track objects robustly.

• 콘크리트학회논문집
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• 제15권4호
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• pp.549-556
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• 2003

시멘트 모르타르의 내마모성, 여러 피착체에 대한 부착성능, 내화학성, 내수성 등의 많은 성능을 개선시키는 데 폴리머 디스퍼젼은 매우 유용한 재료로서 본 실험에 사용한 SBR은 상업적으로 국내에서 생산되고 있는 시멘트 적용성이 우수한 재료이다. 본 실험에서는 시멘트 모르타르에 높은 유동성을 유도하여 자기 평활성을 가지도록 고유동화제와 SBR을 사용하여 시험체를 제작하였으며 SBR에 의한 시험체의 부착강도의 발현 특성을 파악하고자 하였으며 SBR에 의해 개질된 자기 평활성을 가지는 시멘트 모르타르는 재령의 증가에 따라 부착강도는 증가하는 현상을 보여주었으며 파괴형상을 보면 재령이 증가함에 따라 시험체에서 보다는 계면과 피착체에서 외부 인장력에 대하여 파괴가 일어났다. 현재 사무실, 공장, 주차장 등의 바닥 마감재로 널리 사용되고 있는 합성 고분자계 재료인 에폭시 수지나 폴리우레탄 제품은 연도변화가 심하여 가사시간이 상당히 짧다는 것을 확인할 수 있었으며 이에 반하여 본 연구의 시험체는 충분한 가사시간을 확보할 수 있는 이점을 가진 재료로 여겨진다.

• 대기
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• 제26권4호
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• pp.541-551
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• 2016

A real-time quality control algorithm for $PM_{10}$ concentration measured by Continuous Ambient Particulate Monitor (FH62C14, Thermo Fisher Scientific Inc.) has been developed. The quality control algorithm for $PM_{10}$ data consists of five main procedures. The first step is valid value check. The values should be within the acceptable range limit. Upper ($5,000{\mu}g\;m^{-3}$) and lower ($0{\mu}g\;m^{-3}$) values of instrument detectable limit have to be eliminated as being unrealistic. The second step is valid error check. Whenever unusual condition occurs, the instrument will save error code. Value having an error code is eliminated. The third step is persistence check. This step checks on a minimum required variability of data during a certain period. If the $PM_{10}$ data do not vary over the past 60 minutes by more than the specific limit ($0{\mu}g\;m^{-3}$) then the current 5-minute value fails the check. The fourth step is time continuity check, which is checked to eliminate gross outlier. The last step is spike check. The spikes in the time series are checked. The outlier detection is based on the double-difference time series, using the median. Flags indicating normal and abnormal are added to the raw data after quality control procedure. The quality control algorithm is applied to $PM_{10}$ data for Asian dust and non-Asian dust case at Seoul site and dataset for the period 2013~2014 at 26 sites in Korea.

• The Korean Journal of Physiology
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• 제21권1호
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• pp.59-66
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• 1987

This study was aimed to investigate whether the conduction velocity of nerve impulses through the ventral afferent fibers is constant along their entire courses in dorsal as well as in ventral roots. Cats were anesthetized with ${\alpha}-chloralose$ (60 mg/kg, i.p.) and artificially ventilated. Laminectomies were done on L4-S1 spinal vertebrae to expose the lumbosacral spiral cord. Both ventral and dorsal roots of L7 or S1 spinal segments were isolated and cut near the spinal cord. Ventral roots were placed on 6-lead stimulating electrodes and stimulated with supra C-threshold intensity. Divided dorsal root fascicles were placed on bipolar recording electrodes and single fiber units activated by the stimulation of the ventral roots were identified. Followings are the results obtained: 1) A total of 27 VRA units were identified. 10 units of them conducted impulses slower than 2 m/sec. Conduction velocities of the remaining units were in the range of 3.11-20.91 m/sec. 2) In 12 Units conduction velocities Of the VRA units through dorsal$(CV_{DR})$ and venral root$(CV_{DR})$ were determined respectively. There was a tendency to conduct impulses faster through dorsal roots$(CV_{DR}=8.19{\pm}3.26\;m/sec)$ than ventral roots$(CV_{DR}=3.46{\pm}1.02\;m/sec)$. From the above results we confirmed that there exist nerve fibers in continuity between the spinal ventral and dorsal roots but we could not ascertain whether there is a change in conduction velocity through the entire course of ventral afferent unit.

• 한국통신학회논문지
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• 제34권3C호
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• pp.251-256
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• 2009

본 논문에서는 음성신호의 정현파 합성방법 중 하나인 선형위상을 사용한 중첩합산방법에 대하여 감쇄(Damping) 하모닉 크기 파라미터를 사용하여 합성음성의 연속성을 개선시킨 새로운 방법을 제안한다. 기존의 중첩합산 정현파 합성방법은 프레임의 중간 지점에 대한 정현파 파라미터를 얻기 위해서 가중치로 사용된 정현파 크기값을 과거 프레임과 현재 프레임의 평균값을 사용하였으나 제안하는 방법은 정현파 크기값을 단순히 과거와 현재 프레임에서 평균값이 아닌 원 신호와 합성신호 사이의 상관성을 이용하여 감쇄(Damping)요소를 정의하고 보다 정확한 정현파 크기의 파라미터 값을 추출한 후 합성한다. 이렇게 제안한 합성 방법의 성능을 관찰하기 위해 합성방법의 연속성 평가를 통해 기존의 방법과 비교 평가한다. 제안한 방법의 평균 MSE값이 N/2 중첩길이에서 0.251dB, N/4 중첩길이에서 0.298dB 낮아짐을 볼 수 있다.

• Preventive Nutrition and Food Science
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• 제4권1호
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• pp.6-13
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• 1999

The quality of the buckwheat bread made with previously heated ($55^{\circ}C$) and cooled buckwheat flour 0dough with the addition of ascorbic acid(AA) or/and sodium stearoyl lactylate(SSL) was evaluated . With heat treatemtn , handling property of dough and grain of the bread crumb were markedly improved and stickiness of the dough decreased . The optimum resting time to produce the best loaf volume and grain was found to be 3hr for both unheated and heated doughs. Heat treated dough showed higher dough expansion rate during fermentation than unheated dough, even though heated dough had lower loaf volume, probably because of an improper oven spring. Increase in shortening of dough formula from 3% to 5% improved loaf volume without improvement of handling property. With the addition of 100 ppm AA or/and 0.5% SSL, loaf volume and crumb grain were improved for both unheated and heated doughs.Microscopic analysis of a mixed dough by scanning electron microscope (SEM) showed that heated dough had a continuous network whereas unheated dough was discontinuous. The addition of AA and SSL gave the dough a more continuous network whereas unheated dough was discontinuous . The addition of AA and SSL gave the dough a more continuous structure with strengthened strands or interactions between the starch granule and protein. Therefore, it appears that the presence of continuity in heated buckwheat breadwheat bread dough is related to the improved loaf volume and crumb grain without dough stickness.