• Journal of Astronomy and Space Sciences
• /
• v.37 no.2
• /
• pp.143-156
• /
• 2020

Korea Polar Research Institute (KOPRI) installed an ionospheric sounding radar system called Vertical Incidence Pulsed Ionospheric Radar (VIPIR) at Jang Bogo Station (JBS) in 2015 in order to routinely monitor the state of the ionosphere in the auroral oval and polar cap regions. Since 2017, after two-year test operation, it has been continuously operated to produce various ionospheric parameters. In this article, we will introduce the characteristics of the JBS-VIPIR observations and possible applications of the data for the study on the polar ionosphere. The JBS-VIPIR utilizes a log periodic transmit antenna that transmits 0.5-25 MHz radio waves, and a receiving array of 8 dipole antennas. It is operated in the Dynasonde B-mode pulse scheme and utilizes the 3-D inversion program, called NeXtYZ, for the data acquisition and processing, instead of the conventional 1-D inversion procedure as used in the most of digisonde observations. The JBS-VIPIR outputs include the height profiles of the electron density, ionospheric tilts, and ion drifts with a 2-minute temporal resolution in the bottomside ionosphere. With these observations, possible research applications will be briefly described in combination with other observations for the aurora, the neutral atmosphere and the magnetosphere simultaneously conducted at JBS.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.15 no.1
• /
• pp.49-61
• /
• 1993

The transplantation of cartilage, especially auricular cartilage, has assumed a role of importance in the field of plastic and reconstructive surgery. From long years ago, many reports have appeared in the literature describing the experimental and clinical results of the use of cartilage. At present, the evidence for survival of autograft of cartilage is admitted, But, the results for interrelationship between the bone and cartilage grafts with or without perichondrium is not so conclusive. The purpose of this study were observed as to whether autogenous cartilage grafts were fixed by means of tie with 4-0 vicryl and fibrin adhesive on the femur or microscopic findings of union state in 16 rabbits. We sacrified the experimental animals after 1, 2, 4, 6 weeks postoperatively and made the specimens as a routine laboratory procedures and stained with Hematoxylin-Eosin stain, Verhoeff-van Gieson elastic fiber stain, and alcian blue periodic acid-Schiff(AB-PAS) for mucopolysaccharide. Histologic evaluation was performed under microscope. The obtaind results were as follows : 1. Fibrous union was formed between the grafting cartilage and the femur, nor any findings of calcification and formation of new bone. 2. Partial fibrous adhesion was observed in fibrin adhesive groups on 6 weeks postoperatively. 3. Appositional growth has performed more in fibrin adhesive groups than tie groups. 4. There are little difference in both for new copillary proliferation and fibroblast activations. 5. Degenerative changes have apperared more in tie groups than adhesive groups, but not related to the healing periods.

• Korean Journal of Remote Sensing
• /
• v.33 no.5_2
• /
• pp.617-620
• /
• 2017

The periodic monitoring of crop conditions and timely estimation of crop yield are of great importance for supporting agricultural decision-makings, as well as for effectively coping with food security issues. Remote sensing has been regarded as one of effective tools for crop condition monitoring and crop type classification. Since 2010, RDA (Rural Development Administration) has been developing technology for monitoring on crop condition using remote sensing and model. These special papers address recent state-of-the-art of remote sensing and geospatial technologies for providing operational agricultural information, such as, crop yield estimation methods using remote sensing data and process-oriented model, crop classification algorithm, monitoring and prediction of weather and climate based on remote sensing data,system design and architecture of crop monitoring system, history on rice yield forecasting method.

• Korean Journal of Oriental Medicine
• /
• v.16 no.3
• /
• pp.53-66
• /
• 2010

This study focuses on the contents about the Urinalysis which is the most representative one of the Tibetan medicine. Also, this study compares it with the Urinalysis of Traditional Korean medicine. This study focuses on the simple history, the theoretical system, the diagnosis and the urinalysis mainly based on the documents related to the Tibetan medicine. Also, through the comparison with the contents of textbook of Traditional Korean Medicine and the urinalysis shown in the Dongeuibogam(東醫寶鑑) which is the representative Korean medical book, the difference between Tibetan Medicine and Traditional Korean Medicine will be observed. The contents related about the urinalysis of the Tibetan medicine are more specific than those of Traditional Korean Medicine. By observing the color, scent, vapor and sediment of one's urine together with periodic changes more thoroughly, it is possible to find out the cause of a certain disease. However, Traditional Korean Medicine examines the medical conditions mainly based on the state of discharge and fever, showing a clear difference. The Tibetan medicine has an extremely specific type of urinalysis in comparison with that of Traditional Korean Medicine. It is the only characteristic of the Tibet medicine, which cannot be found in any other traditional medicine. By applying the viewpoint of the doctor who diagnoses the patient by measuring his or her pulse, it is possible to make the diagnosing process more specific and accurate. It is expected that the follow-up study will be continuously executed with the introduction of the system for the urinalysis of the Tibetan medicine to Traditional Korean medicine.

• Journal of Ocean Engineering and Technology
• /
• v.21 no.2 s.75
• /
• pp.22-34
• /
• 2007

We present basic data for developing new research topics and closely examine the existing data on the development and organization of the Nakdong River Estuary Delta by analyzing various studies of the area, including ocean engineering, coastal engineering, ocean environmental engineering, geomorphological, and geological studies. We first defined the general concepts related to the estuary and delta and reviewed the historical development of the Nakdong River Estuary Delta over the past 100 years. We then examined the origin and core elements of the estuary deposits that constitute the delta. In addition, we scrutinized the main factors affecting the development of the delta and analyzed existing research on delta development mechanisms by core researchers. The construction of an estuary barrage is one of the main factors effecting estuarine circulation and has altered the physical oceanic environment, area of deposition, atmospheric environment, and vegetation community of the delta. These factors affect the estuary circulation in turn, altering the delta. Along the Nakdong River, an unsteady-state sandy barrier appears at approximately three times the distance of the wavelength of incident offshore waves, and this terrain forms approximately 10-15 years after reclamation in the interdistributary upper stream and transforms the shoreline. It is necessary to develop a technique to predict terrain change that reproduces the erosion and accumulation of estuarine deposits. To determine the parameters and variables necessary to reproduce this system, continuous on-site monitoring is necessary. The existing research did not fully examine the terrain changes in Nakdong River Estuary or the periodic developmental characteristics. To understand the future process of estuary delta development, it is necessary to establish an integrated management system.

• Journal of Korean Society of Steel Construction
• /
• v.22 no.6
• /
• pp.589-597
• /
• 2010

Steel structures have a higher probability of being damaged by fatigue than by other causes of deterioration. As such, their maintenance to prevent fatigue damage is essential to sustain their safety and performance during their service period. In their maintenance, the current state of their fatigue cracks must be assessed to determine appropriate reinforcement methods and the suitable time intervals of periodic inspections when fatigue cracks are detected. Determining the crack growth rate is a successful method of predicting fractures, but it requires technical knowledge on fracture mechanics and experience in numerical methods and software for finite element analysis. In this study, a fatigue crack growth test on through-thickness cracked steel plates was conducted to assess the crack growth rate without superior technical knowledge and experience. The relationship between the Crack Opening Displacement (COD) and the crack growth rate was found in relatively long fatigue cracks.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.22 no.1
• /
• pp.117-125
• /
• 2014

The temperature distribution of steady state rolling tires with detailed tread blocks is numerically predicted using the three dimensional full patterned tire model. A three dimensional periodic patterned tire model is constructed by copying 1-sector mesh in the circumferential direction. Using the static tire contact analysis, the strain cycles during one revolution are approximated with the strains at Guassian points of the elements which are sector-wise repeated within the same circular ring of elements, by neglecting the tire rolling effect. Based upon the multi-axial fatigue theory, the maximum principal strain is used to represent the combined effect of six strain components on the hysteretic loss. In the following, the deformation due to the inflation and vertical load is calculated using ABAQUS. Then heat generation rate in each element is calculated using an in-house code. Lastly, temperature distribution is calculated using ABAQUS again. Through the numerical experiments, the validity of the proposed prediction method is examined by comparing with the experiment and the temperature distribution of a patterned tire model is compared with those of the main-grooved simple tire model.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.1
• /
• pp.1-7
• /
• 2007

Generally, an electric railroad feeding system has many problems due to the different characteristics in contrast with a load of general three-phase AC electric power system. One of them is harmonics problem caused by the switching device existing in the feeding system, and moreover, the time-varying dynamic loads of rail way is inherently another cause to increase this harmonics problem. In Korea power systems, the electric railroad feeding system is directly supplied from the substation of KEPCO. Therefore, if voltages fluctuation or unbalanced voltages are created by the voltage and current distortion or voltage drop during operation, it affects directly the source of supply. The trainloads of electric railway system have non-periodic but iterative harmonic characteristics as operating condition, because the electric characteristic of the electric railroad feeding system is changed by physical conditions of the each trainload. According to the traditional study, the estimation of harmonics has been performed by deterministic way using the steady state data at the specific time. This method is easy to analyze harmonics, but it has limits in some cases which needs an assessment of dynamic load and reliability. Therefore, this paper proposes the probabilistic estimation method, moments matching method(MW) in order to overcome the drawback of deterministic method. In this paper, distributions for each harmonics are convolved to obtain the moments and cumulants of TDD(Total Demand Distortion), and this can be generalized for any number of trains. For the case study, the electric railway system of LAT(Intra Airport Transit) in Incheon International Airport is modeled using PSCAD/EMTDC dynamic simulator. The raw data of harmonics for the moments matching method is acquired from simulation of the LAT model.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.7
• /
• pp.2013-2018
• /
• 2014

The adsorption and decomposition of trimethylene oxide ($C_3H_6O$) molecule on the Al(111) surface were investigated by the generalized gradient approximation (GGA) of density functional theory (DFT). The calculations employed a supercell ($6{\times}6{\times}3$) slab model and three-dimensional periodic boundary conditions. The strong attractive forces between $C_3H_6O$ molecule and Al atoms induce the C-O bond breaking of the ring $C_3H_6O$ molecule. Subsequently, the dissociated radical fragments of $C_3H_6O$ molecule oxidize the Al surface. The largest adsorption energy is about -260.0 kJ/mol in V3, V4 and P2, resulting a ring break at the C-O bond. We also investigated the decomposition mechanism of $C_3H_6O$ molecules on the Al(111) surface. The activation energies ($E_a$) for the dissociations V3, V4 and P2 are 133.3, 166.8 and 174.0 kJ/mol, respectively. The hcp site is the most reactive position for $C_3H_6O$ decomposing.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.16 no.3 s.108
• /
• pp.283-290
• /
• 2006

This study is concerned with static and sinusoidal disturbance rejection for a single periodic input disturbance with known period. In the area of active elimination of a disturbance force, the control input should have two different kinds of gains: one is to deliver a stable control and the other is a force component to cancel the external disturbance force. In this paper we employ a simple state feedback control law to make the balance beam stable and employ a linear observer to estimate the states which represent the external disturbance force components. Simulation results verify our proposed control method to reject a static and sinusoidal disturbance force.