• International Journal of Air-Conditioning and Refrigeration
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• 제17권4호
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• pp.129-134
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• 2009

The objectives of this paper are to study the effects of thermal and geometric conditions on the performance of indoor heat exchangers with R-410A for Gas Engine Driven Heat Pump (GHP) application and to find the optimum design conditions of indoor heat exchangers by parametric analysis for the key parameters. The key parameters are number of tube row, number of tube pipe, fin pitch and transverse tube pitch. In the air side, moisture out of the humid air condenses on the fin surface while the refrigerant (R-410A) boils inside the smooth tube. Therefore this study uses Log Mean Enthalpy Difference (LMHD) method to analyze the heat transfer from the humid air to the refrigerant. This study determines the heat exchanger size, air side/refrigerant side pressure drop and overall heat transfer coefficient. Optimum design conditions for the key parameters are also determined by the parametric analysis. The results show that number of rows and pipes, fin pitch have significant effect on the heat exchanger size. It is also found that the tube length of the louver fin is $17{\sim}30%$ shorter than that of the plate fin.

• Geosystem Engineering
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• 제21권6호
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• pp.326-334
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• 2018

Underground water-sealed gas storage caverns have become the primary method for strategic storage of LPG. Previous studies of excavation blasting effects on large-scale underground water-sealed gas storage caverns are rare at home and abroad. In this paper, the blasting excavation for underground water-sealed propane storage caverns in Yantai was introduced and field tests of blasting vibration were carried out. Field test data showed that the horizontal radial velocity had a major controlling effect in the blasting vibration and frequencies would not cause the vibration velocity concentration effects. In terms of the influence of blasting vibration on adjacent caverns, the dynamic finite element model in LS-DYNA soft was established, whose reliability was verified by field test data. The numerical results indicated the near-blasting side was primary zone for the structural failure and tensile failure tended to occur in the middle of the curved wall on the near-blasting side. Meanwhile, the safety criterions for adjacent caverns based on stress wave theory and according to statistic relationship between peak effective tensile stress and peak particle velocities were obtained, respectively. Finally, with Safety Regulations for Blasting in China (GB6722-2014) taken into account, a final safety criterion was proposed.

• The Journal of Asian Finance, Economics and Business
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• 제9권10호
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• pp.179-188
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• 2022

Professional micro account officers create top-notch state-owned bank human resources using their knowledge, attitudes, characteristics, and talents. Therefore, it is vital to undertake study to ascertain how the performance of micro account officers will impact the personality and leadership style mediated through motivation. The goal of this study is to identify the mediated role of motivation (MOT) in the relationship between micro account officers' performance (citizenship behavior/CB) and leadership styles (LS) and personalities (BFP). Data was collected from 1.510 micro account officers of banks in Indonesia using the causal survey method to determine their citizenship behavior, leadership styles, personality, and role of motivation. The data collected was analyzed by structural equation modeling (SEM), with the result that leadership style, personality, motivation, leadership style, and personality have a significant effect on motivation and citizenship behavior. The interesting findings are related to the role of leadership style, micro account officer's personality, and citizenship behavior mediated by motivation. It was determined that micro account officers' enhanced performance (CB) was assigned by taking into account how their perceived superordinate leadership style, whether transformational direction or reversely by transactional propensity, and features of micro account officer including their personality, which was affected by five factors as well would then be well mediated by motivation.

• Steel and Composite Structures
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• 제38권1호
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• pp.79-86
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• 2021

Due to the complex geological conditions, a large number of high quality coal seams was buried in the western of China which cannot be mining in open-pit methods. The dynamic properties of that coal cannot be studied easily in real site for the complex working condition. The compound coal blocks made on the basis of the real situation were studied in the laboratory. The physical and mechanical properties of the compound coal blocks and the raw coal were contrasted by using the UCS tests. The results show that the compound coal blocks made by mixing coal powder, cement and water in proportion of 2.5:2:1 are the closest to that of standard raw coal. Then the propagation of strain waves and crushing effects on the coal were studied in the compound coal blocks by using the super dynamic strain test system and the numerical calculated method of ANSYS/LS-DYNA. The results show that the diameter of the crushing zone in the compound coal blocks was similar to that in the numerical results. The fractures distribution in laboratory tests also has a similar trend to the calculation results. The measured strain waves at the distance of 50 cm, 100 cm, and 150 cm from the center of the charge are mainly concerned at -1.0×104 με and have a similar trend as that in the numerical simulation.

• 한국해양공학회지
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• 제35권6호
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• pp.403-413
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• 2021

As the size of ships increases, the size and output power of their thrusters also increase. When a large ship berths or unberths, the jet flow produced from its thruster has an adverse effect on the stability of quay walls. In this study, we conducted a numerical analysis to examine the impact of the thruster jet flow of a 30,000 TEU container ship, which is expected to be built in the near future, on the stability of a quay wall. In the numerical simulation, we used the fluid-structure interaction analysis technique of LS-DYNA, which is calculated by the overlapping capability using an arbitrary Lagrangian Eulerian formulation and Euler-Lagrange coupling algorithm with an explicit finite element method. As the ship approached the quay wall and the vertical position of the thruster approached the mound of the quay wall, the jet flow directly affected the foot-protection blocks and armor stones. The movement and separation of the foot-protection blocks and armor stones were confirmed in the area affected directly by the thruster jet flow of the container ship. Therefore, the thruster jet flows of ultra-large ships must be considered when planning and designing ports. In addition, the stability of existing port structures must be evaluated.

• International Journal of Internet, Broadcasting and Communication
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• 제15권1호
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• pp.140-144
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• 2023

In recent years, there are so many serious crashes involving coaches, especially the frontal collision occupies 40% of the front of the vehicle, Frontal collisions account for 100% of the front of the vehicle affecting the driver and side-impact collisions that injure the person in the vehicle. Therefore, the research into improving and optimizing the structure is necessary for risk of injury for passengers in frontal accidents. In this paper, we have designed a Shock absorber that can absorb collision energy. Research using HYPERMESH software. to build the finite element model and calculate the meshing to suit the mesh size of 5mm. apply LS-DYNA software to calculate structural strength. In the study, for a vehicle to collide with a hard obstacle occupying 100% of the head of the vehicle. Then, the experimental design method, Minitab is used for find the structural parameters in the design. Improvement results showed that the acceleration of the impact on passengers and the driver is decreased by 55,17%. The mass of texture improvements is reduced by 11%, according to the requirements of European Standards ECE R94.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1996년도 추계학술대회논문집
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• pp.21-25
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• 1996

The Electomyographic (EMG) signals of flexor-extensor muscle pairs were investigated to identify the neural excitation pattern of low-back pain (LBP) patients during a repetitive bending motion. New parameters and EMG normalization technique were developed to quantitatively represent the difference of temporal EMG patterns between ten healthy subjects and ten LBP patients. Flexor-extensor muscle pairs such as rectus abdominis(RA)-erector spinae (ES at LS), external oblique(EO)-internal oblique(IO), rectus femois (quadriceps: QUD)-biceps femoris(hamstrings:HAM), and tibialis anterior(TA)-gastrocnemius(GAS) pairs of muscles were selected in this study. Results indicated that the temporal EMG pattern such as the peak timing difference of QUD-HAM muscle pair and the duration of coexcitation of ES-RA muscle pair showed a statistically isgnificant difference between healthy subjects and LBP patients. These results indicated that the new technique and parameters could be used as a diagnostic tool especially for LBP patients with soft tissue injuries that are rarely dentified by traditional imaging techniques such as X-ray, CT scan or MRI. Improtantly, the new EMG technique did not require the maximal volutary contraction(MVC) measure for normalization that helped patients minimize the pain experience during and after the session. Further study needs to be made to validate and refine this method for clinical application.

• 한국초전도ㆍ저온공학회논문지
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• 제11권3호
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• pp.46-49
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• 2009

A 3-phase 100m long, 22.9kV class HTS power transmission cable system was developed by Korea Electrotechnology Research Institute (KERI) and LS cable Ltd. those are participated in the 21st Century Frontier project R&D Program of Korea. It is important to test the DC critical current related with its power capacity before applying to the real power grid. In 1995, several international standards organizations including International Electrotechnical Commission (IEC), decided to unify the use of statistical terms related with 'accuracy' or 'precision' in their standards. It was decided to use the word 'uncertainty' for all quantitative (associated with a number) statistical expressions. In this paper, we measured DC critical current of 22.9kV/50MVA superconducting power cable with several voltage tap and analyzed the uncertainty with these results.

• 한국음향학회지
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• 제29권2호
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• pp.97-101
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• 2010

일반적으로 시스템 인식 방법은 입출력에 잡음이 없거나, 출력에만 잡음이 있는 경우를 주 대상으로 한다. 본 논문은 입력 및 출력이 모두 잡음으로 오염되었을 뿐만 아니라 입력에 비해서 출력에 같거나 더 많은 양의 잡음이 개입된 환경에 노출된 Finite Impulse Response 형태의 시스템을 인식하는 새로운 방법을 제안한다. 이를 위해서 입출력의 잡음 수준이 같을 때 최적인 완전최소자승 기법과 출력에만 잡음이 있을 때 최적인 최소자승 기법을 서로 볼록 결합 (convex combination)하여 앞에서 언급한 것과 같은 좀 더 일반화된 잡음 환경에서도 향상된 결과가 나오도록 하였다. 또 제안한 방법이 다양한 잡음 환경에서 응용 가능함을 모의 실험을 통해서 확인하였다.

• 전자공학회논문지CI
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• 제45권6호
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• pp.18-26
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• 2008

본 논문에서는 IEEE 802.15.4망의 표준 프레임 구조를 이용한 무선 제어 시스템의 구현을 위해 신뢰성 및 실시간성을 고려한 체계적인 전송 기법을 제안하였다. 제안된 실시간 전송 기법은 공장 환경에서 무선 제어 네트워크가 주어진 시간 구간 내에 실시간 혼합 데이터(실시간 주기 데이터, 긴급 데이터, 비실시간 메시지 데이터)를 효율적으로 처리하는 기능을 제공한다. 이를 위하여 IEEE 802.15.4의 슈퍼프레임의 구조적 특징을 응용하여 실시간 혼합 데이터의 효율적인 전송을 위한 전송 기법들을 설계했다. 제안된 기법은 실시간 및 비실시간 데이터 간에 독립적인 처리 알고리즘을 적용하기 때문에 전체적인 제어 네트워크의 성능 향상을 가져올 수 있다. 제안된 전송 기법의 효용성을 증명하기 위하여 OPnet Modeler 기반의 IEEE 802.15.4 시뮬레이션 모델을 구현하였고 주어진 주기 및 긴급 데이터의 실시 간성을 분석하였다.