• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.238-243
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• 2011

This study compared Kd, loss factor and thickness of floor impact isolator by loading/unloading heat treatment with results by continuous loading treatment and checked problem and improvement method of heat treatment condition for the long-term stability evaluation of the floor impact isolation. As the results, it is required the change of heat treatment condition unloading now to loading as actual weigh on the floor impact isolator.

• 로봇학회논문지
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• 제19권1호
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• pp.79-91
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• 2024

Large warehouses are building automation systems to increase efficiency. However, small warehouses, military bases, and local stores are unable to introduce automated logistics systems due to lack of space and budget, and are handling tasks manually, failing to improve efficiency. To solve this problem, this study designed small loading and unloading equipment that can be mounted on transportation vehicles. The equipment can be controlled remotely and is automatically controlled from the point where pallets loaded with cargo are visible using real-time video from an attached camera. Cargo recognition and control command generation for automatic control are achieved through a newly designed deep learning model. This model is designed to be optimized for loading and unloading equipment and mission environments based on the YOLOv3 structure. The trained model recognized 10 types of palettes with different shapes and colors with an average accuracy of 100% and estimated the state with an accuracy of 99.47%. In addition, control commands were created to insert forks into pallets without failure in 14 scenarios assuming actual loading and unloading situations.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.335-342
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• 2000

In this study, the swelling characteristics of reconstituted clayey soil were investigated by STD and CRS test. The strain rate during loading was constant i.e. 0.05 %/min, 0.03 %/min and during unloading was varied in proportion to 1/1, 1/5, 1/10 and 1/15 of strain rate during loading. From this study the following conclusions were obtained; (1) There were similar values, especially, during unloading in case of 1/10 or 1/15 of strain rate during loading and the test results between STD and CRS were much to be alike. (2) The cross point of effective stress versus excess pore water pressure ratio curve, was increased during unloading, while the stress level of the cross point was decreased. The stress level can be separated into two zones according to the swelling index named Cs1 and Cs2. From the test results, the values of Cs1 were approximately constant irrespective of strain rate during unloading, but the values of Cs2 were much influenced by strain rate. (3) In CRS consolidation tests, it was found that unloading strain rate did not affect on the existence of zone.

• 대한안전경영과학회지
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• 제12권4호
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• pp.273-278
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• 2010

As basic study on effects of the decasualization of port labor, this paper watched labor supply framework reorganization, focused on port worker in Incheon port at before decasualization(2005~2007.9) and after decasualization(2007.10~2010.5) and analyzed disposal quantity, workers, workdays, productivity, accident and disaster data that was apt to influence by the decasualization of port labor. Though commercial traffic of Incheon port was decreased in global economic depression, individual workday per month after decasualization compared with before decasualization is decreased by 3.3days from 22.7day to 19.4days, on the other hand, indivisual annual loading and unloading throughput is increased averagely 71.6%, and labour productivity, when 2005 labour productivity are 100, are increased by 67%. After decasualization, overall loading and unloading productivity is improved. But, according to loading and unloading, the number of accident and disaster are increase by 11.7% after decasualization for loading and unloading operation.

• Geomechanics and Engineering
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• 제32권1호
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• pp.97-110
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• 2023

The coefficient of lateral earth pressure at rest in loose sand during virgin loading, K₀ , and during unloading, K'₀ , have been determined from laterally confined load-unload tests. The tests included measurement of lateral pressure with null pressure gauges, side wall friction with newly designed friction meters and applied pressure and base pressure with load cells. The importance of accounting for side-wall friction when evaluating the distribution of vertical pressure over the height of the soil specimen was demonstrated. Relatively uniform friction was observed during loading, but this was not the case during unloading unless friction reduction measures were employed. While the measured value of K₀ was found to be close to, if slightly higher than the value commonly estimated on the basis of friction angle, φ', the ratio of K'₀ to K₀ was found to reasonably fit an expression of the form K'₀/K₀ = 1 + C·log(OCR), with C equal to 1 in the present tests.

• 대한기계학회논문집A
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• 제26권1호
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• pp.113-120
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• 2002

Experimental procedure to measure fracture toughness (J$_{c}$) under mixed mode loading using CTS(Compact Tension-Shear) specimens is described. It\`s loading angle ranges from 0$^{\circ}$ to 45$^{\circ}$ with interval of 157. The general outline of experimental procedure is similar to that of ASTM E8l3-89 fur mode I fracture. Equations fur determining J-integral is quoted from the authors' previous works. The relation between unloading compliance and physical crack size was calibrated. As an example, fracture toughness of aluminum alloy 2024p-7361 was measured and some reasonable results of J$_{c}$ with various loading angles were obtained.

• 한국화재소방학회논문지
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• 제23권2호
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• pp.27-35
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• 2009

본 연구는 질석계 내화피복재를 뿜칠한 단순지지 TSC 합성보에 대해 하중 재하의 영향과 합성보의 형상, 웨브에 설치한 메탈라스의 영향 등을 변수로 내화성능 평가를 하였다. 내화피복재는 3시간 내화성능의 요구치가 40mm 이나 25mm만 뿜칠 후 내화실험을 실시하였다. 또한 강재 표면이 부착강도에 미치는 영향도 확인하였다. 실험결과 TSC 합성보에 25mm의 내화피복재를 뿜칠한 경우 재하와 비재하시험 모두 3시간의 내화성능을 확보하는 것으로 나타났다. 재하와 비재하에 대한 내화성능 기준으로 온도를 비교하면, 평균온도는 $250^{\circ}C$ 이하, 최고온도는 $310^{\circ}C$ 이하가 되었다. 또한 보의 형상 및 메탈라스의 부착 유소(昭)' 등에 의한 온도의 영향은 없었다.

• Smart Structures and Systems
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• 제30권4호
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• pp.353-369
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• 2022

In this paper, a new sensor chip with frequency reconstruction range of 2.252 GHz ~ 2.450 GHz is designed and fabricated. On this basis, a self-designed "T-shaped" shell is added to overcome the disadvantage of uneven deformation of the traditional steel shell, and the range of the sensor chip is expanded to 0 kN ~ 96 kN. The liquid metal antenna is used to carry out a step-by-step loading test, and the relationship between the antenna resonance frequency and the pressure load is analyzed. The results show that there is a good linear relationship between the pressure load and the resonant frequency. Therefore, the liquid metal antenna can be regarded as a pressure sensor. The cyclic loading and unloading experiments of the sensor are carried out, and different loading rates are used to explore the influence on the performance of the sensor. The loading and unloading characteristic curves and the influence characteristic curves of loading rate are plotted. The experimental results show that the sensor has no residual deformation during the cycle of loading and unloading. Moreover, the influence of temperature on the performance of the sensor is studied, and the temperature correction formula is derived.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.1156-1167
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• 2010

The constant rate of strain (CRS) consolidation test has been widely used to evaluate consolidation characteristics of soils instead of the standard Incremental Loading Test. In practical problems, after the ground improvement, the condition of the soil is over-consolidated. Therefore, it is important to determine the recompression indices and the coefficient of consolidation(or the coefficient of swelling) of unloading-reloading cycle to predict the settlement behavior. However, since standard testing procedures or studies related with strain rate are insufficient especially in unloading-reloading cycle, it is difficult to predict the settlement field behavior accurately from the CRS consolidation test results in spite of its lots of strengths. The several CRS consolidation tests were performed changing the unloading strain rate from 0.2%/hr to 20%/hr with vertical drainage condition using the reconstituted kaolinite sample. For the reconstituted kaolinite sample in CRS consolidation test, the recompression indices are insensitive to the strain rate. It is revealed that the coefficient of consolidation of reloading is affected by the developed pore pressure during unloading. Additionally, the test should be conducted in the positive pore pressure ratio range (3~15%) to obtain the reasonable coefficient of consolidation in the whole range(loading, unloading and reloading).

• 제어로봇시스템학회논문지
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• 제11권9호
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• pp.816-821
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• 2005

The remote operation of $4\~5$ cranes for container loading/unloading at a port by one operator will dramatically improve loading/unloading efficiency through productivity increase, cost reduction, and so on. This study develops a remote crane control system for container loading/unloading yard cranes. First, a wireless video and audio system to transmit views and sounds of the working field is designed by using 3 web cameras and a microphone. Next, a RSVP-based multi-path reservation method is presented with a view to improving the quality of service in the communication network for remote control. Simulation results show that a RSVP-based multi-path reservation can enhance the reservation success rate in the TCP/IP network.