Dynamic Job-shop Scheduling Program (DJSP) Analysis for Preventive Military Helicopter Maintenance System (PMS)

Republic of Korea Army(ROKA) has been founding new attack helicopter troops since last year by adopting US main attack helicopter, AH-64E Apache, and peripheral system like pilots and mechanics training systems and their organization. The AH-64E Apache is a major attack helicopter of the US Army and all of its systems are verified in terms of the effectiveness in real operations for several decades. However, ROKA still needs their own version of systems including tactics, template, and maintenance which are suitable for Korean terrain, climate, personnel, and so on. At least ROKA needs to have a chance to verify that the adopted system is working well with different circumstances, especially with a different maintenance system. As basic characteristics, routine maintenance and management are essential for accident prevention for a helicopter, there are specially formalized maintenance systems for every kind of helicopter respectively. It was established by a manufacturer in maintenance manuals and can be modified and integrated by users and operators. Apache also has its own maintenance schedule and system including 25-hour, 50-hour, 125-hour, and 250-hour maintenance and inspections which are implemented according to the operation hours. Those schedules are done by a task force or temporary maintenance team which is led by one or two inspectors and supported by 3~4 mechanics. Maintenance troops restrict the number of aircraft to get in the process by managing the flight hours considering the limit of manpower and equipment so that the operation rate stays above at least 80%. It is important to stipulate their capacity in need and max capacity with given personnel and facility for newly founding military troops. Especially since ROKA aviation branch is applying a more strict maintenance process, it might cause insufficiency of resources if organized by same template and procedure with the US Army. The goal of this study is to verify if existing personnel organization is affordable for new maintenance system of AH-64 Apache helicopters. As a further step ahead, this research found the most critical personnel pool and their relationship by sensitivity analysis. This research specified actual maintenance procedure and restrictions on computer and simulated virtually. During the repetition of the test, existing organization was found inadequate to satisfy all restrictions and requirements. Test pilot and inspector pool are critical to secure the successful maintenance support and to prepare for contingency. Also, there were interesting relationships between the mechanics groups. They are in supplemental relationships with each other because of the condition of one pool affects the other

Master of Science

thesisTo get reliable location and time information for specific objects, the U. S. Department of Defense (DOD) developed the Global Positioning System (GPS). In spite of its enormous advantages, it encounters limitations in GPS-denied or compromised environments. To address these limitations, Inertial Motion Units (IMUs), consisting of gyroscopic devices, have been substituted for GPS in these harsh environments. However, they are also limited by bias, which increases error growth by integrating signals. This research project allows for tracking a pedestrian in GPS-limited environments by adding another portable localization system to the IMU, the Ground Reaction Sensor Cluster (GRSC). The GRSC measures the precise velocity of an object by applying zero velocity updating (ZUPTing) events, and seeks to compensate for the limitations of the IMU to give the precise position of the pedestrian. This project addresses the testing environment developed to evaluate the reliability of a shoe-mounted GRSC. This environment consisted of both physical measurements and analysis of the data. Through this testing, we check whether this device would meet the Defense Advanced Research Projects Agency's (DARPA) requirement to resolve the zero-velocity error biases of 4000, 250 and 20 um/s with a typical 0.3s midstance measurement time. To ensure an adequate amount of data, the process was automated and run for several different cycle lengths

Construction of Product Appearance Kansei Evaluation Model Based on Online Reviews and FAHP: A Case Study of Household Portable Air Conditioners

Meeting the personalized needs of users is the key to achieving the sustainable success of a product. It depends not only on the product’s functionality but also on satisfying users’ emotional needs for the product’s appearance. Therefore, researchers have been conducting research focusing on Kansei engineering theory to determine users’ emotional needs effectively. The initial process involves accurately extracting and filtering emotional data and Kansei words from consumers. Thus, we propose an evaluation model to efficiently obtain, screen, and sort these Kansei words based on Kansei engineering, using household portable air conditioners as research subjects. By integrating techniques for online user comment mining methods, users’ Kansei terms related to the product’s appearance can be gathered efficiently. These terms are then combined with image samples and filtered to determine a final set of 16 Kansei word pairs. Subsequently, the fuzzy analytic hierarchy process (FAHP) is utilized to prioritize these terms, and the fuzzy comprehensive evaluation (FCE) method is used to validate the results and determine the applicability of the evaluation model. The results showed that Kansei words could be quickly and objectively acquired using existing text mining techniques on online reviews. Moreover, the weights of different Kansei terms of the product’s appearance in the consumer’s perception are accurately produced through the FAHP. This evaluation model marks a significant advancement in accurately obtaining users’ emotional data in Kansei engineering. It offers valuable guidance for designing products that meet users’ personalized needs, enhancing design efficiency and reducing resource wastage at the early stages of designing, and improving the sustainability development of Kansei engineering

High-speed and high-SNR photoacoustic microscopy based on a galvanometer mirror in non-conducting liquid

Optical-resolution photoacoustic microscopy (OR-PAM), a promising microscopic imaging technique with high ultrasound resolution and superior optical sensitivity, can provide anatomical, functional, and molecular information at scales ranging from the microvasculature to single red blood cells. In particular, real-time OR-PAM imaging with a high signal-to-noise ratio (SNR) is a prerequisite for widespread use in preclinical and clinical applications. Although several technical approaches have been pursued to simultaneously improve the imaging speed and SNR of OR-PAM, they are bulky, complex, not sensitive, and/or not actually real-time. In this paper, we demonstrate a simple and novel OR-PAM technique which is based on a typical galvanometer immersed in non-conducting liquid. Using an opto-ultrasound combiner, this OR-PAM system achieves a high SNR and fast imaging speed. It takes only 2 seconds to acquire a volumetric image with a wide field of view (FOV) of 4 x 8 mm(2) along the X and Y axes, respectively. The measured lateral and axial resolutions are 6.0 and 37.7 mu m, respectively. Finally, as a demonstration of the system's capability, we successfully imaged the microvasculature in a mouse ear in vivo. Our new method will contribute substantially to the popularization and commercialization of OR-PAM in various preclinical and clinical applications.11Ysciescopu

2D Genus Topology of 21-cm differential brightness temperature during cosmic radiation

A novel method to characterize the topology of the early-universe intergalactic medium during the epoch of cosmic reionization is presented. The 21-cm radiation background from high redshift is analyzed through calculation of the 2-dimensional (2D) genus. The radiative transfer of hydrogen-ionizing photons and ionization-rate equations are calculated in a suite of numerical simulations under various input parameters. The 2D genus is calculated from the mock 21-cm images of high-redshift universe. We construct the 2D genus curve by varying the threshold differential brightness temperature, and compare this to the 2D genus curve of the underlying density field. We find that (1) the 2D genus curve reflects the evolutionary track of cosmic reionization and (2) the 2D genus curve can discriminate between certain reionization scenarios and thus indirectly probe the properties of radiation-sources. Choosing the right beam shape of a radio antenna is found crucial for this analysis. Square Kilometer Array (SKA) is found to be a suitable apparatus for this analysis in terms of sensitivity, even though some deterioration of the data for this purpose is unavoidable under the planned size of the antenna core