• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.10
• /
• pp.1207-1218
• /
• 2013

It is difficult to predict derailment with the existing derailment coefficient like Nadal's formula which is based on the contact forces between one wheel and rail. A new derailment coefficient model developed on a wheelset is able to make a better estimate about the climb derailment, slip derailment, roll over derailment, and mixed derailment types of these. Moreover, not only the mechanical factors considered in the existing derailment coefficients but also other various factors affecting derailment such as wheel unloading and loading, diameter of wheel, and locations of axle-box bearings can be covered with this new derailment coefficient model. That is, the derailment patterns which couldn't be solved with the existing formulas such as Nadal's and Weinstock's models can be analyzed with this wheelset derailment coefficient model because of considering various factors causing derailment. Finally, the validity of the new derailment coefficient model is verified using dynamic model simulations.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.31 no.3
• /
• pp.91-106
• /
• 2003

The objective of this study is to present management methods for Korean golf courses to achieve fast green that satisfies international golf tournament standards during an official golf tournament. The results of both the research and the comparative study on putting green management of 24 tournaments hosted in Korea and 12 tournaments hosted in overseas countries in 2002 are as follows: 1. As for the putting greens in Korean and foreign golf courses where official golf tournaments were held, Korean of official golf tournaments were mainly opened in two-green system golf courses contrary to the foreign cases, and the average size of the greens in Korean golf courses was shown to be greater than that of foreign golf courses to some extent, although there was no difference between the types of turf varieties. 2. Results have shown that unlike foreign golf courses, Korean golf courses were managing putting greens by using greens mowers mostly for general (non-tournament) management, and elaborate rolling attempts failed during official tournament flay week because of an insufficient number of rollers to be input. Therefore, Korean golf courses are required to make efforts to secure 21-inch working-behind greens mowers equipped with tournament bedknifes and 11 blades, which is the greens mowing equipment for professional tournaments, and rollers above all things in order to achieve fast green during tournament play week 3. In attempting to achieve green as fast as that of foreign golf courses, Korean golf courses need to consider the method of performing mowing at 3.0mm height or less with greens mowers for professional tournaments. This needs to be done more than two times, followed by a continuous practice of rolling for proper management.

• Journal of Industrial Convergence
• /
• v.18 no.3
• /
• pp.109-116
• /
• 2020

The purpose of this study is to make suggestions for the infectious disease surveillance systems as part of the government's healthcare policy intended to minimize damage by implementing an appropriate and swift crisis management in the event of future infectious disease outbreaks. To that end, this descriptive study analyzes the infectious disease outbreaks and the management and control thereof in Korea and other countries, so as to suggest some approaches to infectious disease surveillance systems applicable to affected regions. The analysis results shed light on the causes of the spread of future infectious diseases over the past years, and the management systems that could possibly deal with the trial and error in the response policy. It seems crucial to roll out appropriate information, training and promotion programs as part of the national disaster response systems to prevent infectious diseases in relation to the roles of multiple relevant government agencies in the event of disasters especially amid the COVID-19 pandemic.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.38 no.3
• /
• pp.21-28
• /
• 2015

As film products are increasingly used in a wide range of areas, from producing traditional flexible packaging to high-tech electronic products, a higher level of quality is demanded. Most film products are made in the form of rolled finished goods, therefore, various quality issues related to their shape characteristics must be addressed. The thickness of the film products is one of the most common and important critical-to-quality attributes (CTQs). Particularly, the degree of thickness uniformity is more important than other thickness parameters, because it will be potential causes of many secondary thickness-related quality problems, such as wrinkles or faulty windings. To control the degree of thickness uniformity, the fixed bending region is oneof the most important CTQs to manage. Fixed bending regions are special points in the transverse direction of a rolled product with consistent minute variations of the thickness gap. This paper describes the measurement and analysis of thickness uniformity data, which were performed in a real manufacturing field of biaxial oriented polypropylene (BOPP) film. In previous researches, quality function deployment (QFD) or fault tree analysis were used to find the most critical process attributes out to controlthe CTQ of thickness uniformity. Whereas, this paper uses traditional control charts to find the most critical process attributes out in this problem. In addition, the selection of one of the major critical process attributes (CTPs) that is expected to affect the CTQ of thickness uniformity is also described. The selected critical-to-process attributes are the controlled temperatures along the transverse direction. A dramatic improvement in thickness uniformity was observed when the selected CTPs were controlled.

• Korean Journal of Metals and Materials
• /
• v.47 no.7
• /
• pp.433-439
• /
• 2009

Ti and Ti based hydrogen storage alloys have been thought to be the third generation of alloys with a high hydrogen capacity, which makes it difficult to handle because of high reactivity. In order to solve the problem, the activation of a wide range of hysteresis of hydriding/dehydriding and without degradation of hydrogen capacity due to the hydriding/dehydriding cycle have to be improved in order to be aplied. Ti-Cr alloys have a high capacity about 0.8 wt.% in an ambient atmosphere. When the Ti-Cr alloys are added to Nb and Ta elements, they formed a laves phase in the alloy system. The Nb element was expected to make easy diffuse hydrogen in the Ti-Cr storage alloy, which was a catalytic element. In this study, the Ti-Nb-Cr ternary alloy was prepared by melt spinning. As-received specimens were characterized using XRD (X-ray Diffraction), SEM (Scanning Electron Microscopy) with EDX (Energy Dispersive X-ray) and TG/DSC (Thermo Gravimetric Analysis/Differential Scanning Calorimetry). In order to examine hydrogenation behavior, the PCI (Pressure-Composition-Isotherm) was performed at 293, 323, 373 and 423 K.

• Journal of Korean Society for Atmospheric Environment
• /
• v.34 no.5
• /
• pp.639-650
• /
• 2018

Identification of the major sources contributing to PM is of importance in order to understand their quantitative contributions to atmosphere. In the viewpoint of the meat cooking in Korea, only a few analyses of organic molecular markers have been conducted due to analytical difficulties. In this study, ten different parts of meat (i.e., blade shoulder, belly, and arm shoulder of pork; ribeye roll, top blade muscle, and short plate of beef; leg quarter, breast, and wing of chicken; duck; mackerel) were pyrolyzed to generate the cooked PM using an electronic heating plate. Generated PM were collected by the pyrolysis sampling system to identify total carbon (TC) using a carbon analyzer and cholesterol using a Liquid chromatography tandem-mass spectrometry (LC-MSMS) based on fragmentor voltage (FV), precursor ion, collision energy, product ion. In addition, oxydative potential (OP) analysis using dithiothreitol (DTT) method were discussed to investigate the toxicity relates. Highly correlated pairwise scatterplots between the cholesterol and TC indicate that oxydative potential was highly associated with different parts of meat. This study provides insight into the meat cooking components of PM, which could be drivers of the oxidative potential relates.

• Journal of Biosystems Engineering
• /
• v.28 no.4
• /
• pp.305-314
• /
• 2003

The ROPS of an agricultural tractor is designed to protect its driver when the tractor overturns. Although the current OECD tests to determine whether the ROPS meets the requirements of the OECD regulation are desirable, they need long time to test. We experimental time and effort by using CAE. We conducted a finite element analysis for the ROPS design of a Dae-Dong tractor cabin in an attempt to reduce the design and manufacturing time. This study shows the interpretative skill using MARC(v.2000) for designing ROPS and difference between the results of testing and FEA. Design process is generally divided into two phases: a concept and a detail design. The concept design uses simple analysis to predict structural behavior, whereas the detail design involves a finite element analysis performed by the results of the concept design. This study focused on the detail design and used Patran(v.2000r2) and MARC(v.2000) of the MSC software corporation. The model consisted of 4812 elements and 4582 nodes. Four tests. specified in the OECD standards, were performed: (1) longitudinal loading test (2) rear crushing test (3) side loading test (4), and front crushing test. Independent analyses were also performed for each test, along with a sequential analysis. When compared, the results of the independent and sequential analyses were found to be similar to the test results.

• Journal of the Institute of Convergence Signal Processing
• /
• v.19 no.2
• /
• pp.54-60
• /
• 2018

In this paper, we propose an efficient automatic control method for the collision avoidance of drones. In general, the drones are controlled by transmitting to the flight control (FC) module the received PWM signals transmitted from a RC controller which transduce movements of the knob into PWM signal. We implemented the collision avoidance module in-between receiver and FC module to monitor and change the throttle, pitch and roll control signals to avoid drone collision. In order to avoid the collision, a LiDAR distance sensor and a servo-motor are installed and periodically measure the obstacle distance within -45 degrees from 45 degrees in flight direction. If the collision is predicted, the received PWM signal is changed and transmitted to the FC module to prevent the collision. We applied our proposed method to a hexacopter and the experimental results show that the safety is improved because it can prevent the collision caused by the inadvertency or inexperienced maneuver.

• Journal of the Korean Society for Railway
• /
• v.10 no.5
• /
• pp.540-545
• /
• 2007

The tilting train is able to tilt its body towards the center of the turning radius, preventing roll-over of the train as it runs on a curved rail at high-speed. This train, widely accepted for commercial purpose internationally, is very beneficial in that the operating time is shortened without much capital investment to the infrastructure where there are many curved rails. Over several years, the Korea Railroad Research Institute (KRRI) has developed such a train. In this paper, the safety of the Korean tilting train express (TTX) is investigated using a dynamic simulation model. Since proper safety standards have not been established for the TTX, those for the Korean train express (KTX) is employed to analyze the safety and ride comfort of the TTX. This study is useful in predicting the behavior of the TTX and ride comfort, and conforms that designed TTX is stable enough to satisfy the safety standards. It would be useful to recommend proper normal operating speed and determine the maximum safety speed, according to the result. Furthermore, it would be possible to provide basic reference data when analyzing the dynamic effect of the catenary system and the fatigue of the bogie.

• Journal of Biomedical Engineering Research
• /
• v.44 no.6
• /
• pp.384-391
• /
• 2023

Among the elderly, fatal injuries and deaths are significantly attributed to falls. Therefore, a pre-impact fall detection system is necessary for injury prevention. In this study, a robust threshold-based algorithm was proposed for pre-impact fall detection, reducing false positives in highly dynamic daily-living movements. The algorithm was validated using public datasets (KFall and FARSEEING) that include the real-world elderly fall. A 6-axis IMU sensor (Movella Dot, Movella, Netherlands) was attached to S2 of 20 healthy adults (aged 22.0±1.9years, height 164.9±5.9cm, weight 61.4±17.1kg) to measure 14 activities of daily living and 11 fall movements at a sampling frequency of 60Hz. A 5Hz low-pass filter was applied to the IMU data to remove high-frequency noise. Sum vector magnitude of acceleration and angular velocity, roll, pitch, and vertical velocity were extracted as feature vector. The proposed algorithm showed an accuracy 98.3%, a sensitivity 100%, a specificity 97.0%, and an average lead-time 311±99ms with our experimental data. When evaluated using the KFall public dataset, an accuracy in adult data improved to 99.5% compared to recent studies, and for the elderly data, a specificity of 100% was achieved. When evaluated using FARSEEING real-world elderly fall data without separate segmentation, it showed a sensitivity of 71.4% (5/7).