• Journal of Biomedical Engineering Research
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• v.25 no.2
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• pp.157-163
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• 2004

Nitrogen ion implantation and ion plating techniques were applied for improvement of the wear resistance of metallic implant materials. In this work, the wear dissolution behaviour of a nitrogen ion implanted super stainless steel (S.S.S, 22Cr-20Ni-6Mo-0.25N) was compared with those of S.S.S, 316L SS and TiN coated 316L SS. The amounts of Cr and Ni ions worn-out from the specimens were Investigated using an electrothermal atomic absorption spectrometry. Furthermore, the Ti(Grade 2) disks were coated with TiN, ZrN and TiCN by use of low temperature arc vapor deposition and the wear resistance of the coating layers was compared with that of titanium. The chemical compositions of the nitrogen ion implanted and nitride coated layers were examined with a scanting auger electron spectroscopy. It wat observed that the metal ions released from the nitrogen ion implanted S.S.S surface were significantly reduced. From the results obtained, it was shown that the nitrogen ion implanted zone obtained with 100 KeV ion energy was easily removed within 200,000 revolutions from a wear dissolution testing under a similar load condition when applied to artificial hip joint. The remarkable improvement in wear resistance weir confirmed by the nitrides coated Ti materials and the wear properties differ greatly according to the chemical composition of the coating layers. for specimens with the same coating thickness of about 3$\mu\textrm{m}$, TiCN coated Ti showed the highest wear resistance. However, after removing the coating layers, the wear rates of all nitrides coated Ti reverted to their normal rates of below 10,000 revolutions from Ti-disk-on-disk wear testing under the same load condition. From the results obtained, it is suggested that the insufficient depth of the 100 Kel N$\^$＋/ ion implanted zone and of the nitrides coated layers of 3$\mu\textrm{m}$ are subject to restriction when used as frictional parts of load bearing implants.

• The Journal of Korean Society for Radiation Therapy
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• v.17 no.1
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• pp.33-40
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• 2005

Purpose : We recently perform the latest radiotheraphy (3D conformal, IMRT,etc.) with the development of 3D CT planning technology. However, in case patients with breast cancer, it is difficult to acquire the CT image with the limitation of CT hole size and tilting of breast immobilization device. The Ewha Breast Device(EBD) was constructed to improve the problem in the treatment of patients with breast cancer and we are intend to introduce the procedure of the EBD construction in this study and compare the EBD with conventional breast device in the view point of usefulness. Materials and Methods : We have constructed the EBD with acryl, analyze the skull size with CT data, consider the skin folder in SCL field and evaluated the EBD usefulness from the view point of set-up reproducibility, dose distribution, skin reaction in comparison with conventional breast device. Results : In the case of patients set-up error analysis, the EBD is superior to conventional device in portal film repetition($\%$) check (80pt.), equal to that in simulation & CT image coincidence check(5pt.). There is no difference between the two systems in dose distribution and skin reaction in SCL field is better the EBD than conventional device. Conclusions : The construction of the EBD enable us to perform the latest radiotheraphy in breast treatments, relieve the pains in simulation, and reduce, the skin reaction. In the future, we expect that modification of the EBD is useful in treating for patients with breast cancer.

• Research in Plant Disease
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• v.15 no.3
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• pp.187-192
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• 2009

Pepper powdery mildew, Leveillula taurica is one of the most important pathogens of pepper in the greenhouses and fields in Korea and is becoming a worldwide disease. These experiments were carried out to investigate the optimal germination, disease development conditions, disease incidence and effective inoculation methods of pepper powdery mildew. The incidence of powdery mildew was investigated throughout the country based on the major pepper growing areas in 2009. The average rate of infected leaves ranged from 15.3% to 81.8% in greenhouses and fields. Powdery mildew incidences were more severe in greenhouses than those of fields. The optimal temperature for conidial germination was $25^{\circ}C$ and showed the highest germination at 6 hs after treatment. The range of temperature for germination was $10^{\circ}C$ to $35^{\circ}C$. Temperature of greater than $30^{\circ}C$ and below $20^{\circ}C$ affected the abnormal germination and germ tube elongation. The optimal relative humidity for germination and germ tube elongation was 85% and germination increased as relative humidity increased. Disease development started 8 days after inoculation and showed the highest disease severity at 15 days in greenhouse and field regardless of varieties. Among three different inoculation methods tested the spore dropping method was better than touching with infected leaves and spraying with spore suspension. However, the method has limitation in mass inoculation due to the amount of time consumed.

• Korean Journal of Remote Sensing
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• v.35 no.6_4
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• pp.1319-1326
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• 2019

The KARI(Korea Aerospace Research Institute) operates the government satellite information application consultation to cope with ever-increasing demand for satellite images in the public sector, and carries out various support projects including the generation and provision of mosaic images on the Korean Peninsula every year to enhance user convenience and promote the use of satellite images. In particular, the government has wanted to increase the utilization of mosaic images on the Korean Peninsula and seek to classify and update mosaic images so that users can use them in their businesses easily. However, it is necessary to test and verify whether the classification results of the mosaic images can be utilized in the field since the original spectral information is distorted during pan-sharpening and color balancing, and there is a limitation that only R, G, and B bands are provided. Therefore, in this study, the reliability of the classification result of the mosaic image was compared to the result of KOMPSAT-3 image. The study found that the accuracy of the classification result of KOMPSAT-3 image was between 81~86% (overall accuracy is about 85%), while the accuracy of the classification result of mosaic image was between 69~72% (overall accuracy is about 72%). This phenomenon is interpreted not only because of the distortion of the original spectral information through pan-sharpening and mosaic processes, but also because NDVI and NDWI information were extracted from KOMPSAT-3 image rather than from the mosaic image, as only three color bands(R, G, B) were provided. Although it is deemed inadequate to distribute classification results extracted from mosaic images at present, it is believed that it will be necessary to explore ways to minimize the distortion of spectral information when making mosaic images and to develop classification techniques suitable for mosaic images as well as the provision of NIR band information. In addition, it is expected that the utilization of images with limited spectral information could be increased in the future if related research continues, such as the comparative analysis of classification results by geomorphological characteristics and the development of machine learning methods for image classification by objects of interest.

• Korean Journal of Remote Sensing
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• v.27 no.4
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• pp.467-480
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• 2011

Spatial and temporal variabilities of NPP(Net Primary Production) retrieved from two satellite instruments, AVHRR(Advanced Very High Resolution Radiometer, 1981-2000) and MODIS(MODerate-resolution Imaging Spectroradiometer, 2000-2006), were investigated. The range of mean NPP from A VHRR and MODIS were estimated to be 894-1068 $g{\cdot}C/m^2$/yr and 610-694.90 $g{\cdot}C/m^2$/yr, respectively. The discrepancy of NPP between the two instruments is about 325 $g{\cdot}C/m^2$/yr, and MODIS product is generally closer to the ground measurement than AVHRR despite the limitation in direct comparison such as spatial resolution and vegetation classification. The higher NPP values over South Korea are related to the regions with higher biomass (e.g., mountains) and higher annual temperature. The interannual NPP trends from the two satellite products were computed, and both mean annual trends show continuous NPP increase; 2.14 $g{\cdot}C/m^2$/yr from AVHRR(1981-2000) and 6.08 $g{\cdot}C/m^2$/yr from MODIS (2000-2006) over South Korea. Specifically, the higher increasing trends over the Southwestern region are likely due to the increasing productivity of crop fields from sufficient irrigation and fertilizer use. The retrieved NPP shows a closer relationship between monthly temperature and precipitation, which results in maximum correlation during summer monsoons. The difference in the detection wavelength and model schemes during the retrieval can make a significant difference in the satellite products, and a better accuracy in the meterological and land use data and modeling applications will be necessary to improve the satellite-based NPP data.

• Radiation Oncology Journal
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• v.25 no.4
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• pp.206-212
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• 2007

Purpose: Heterotopic ossification is a well-known postoperative and post-traumatic complication of the elbow. We reviewed the treatment outcome for the use of low-dose radiation after surgical intervention of the elbow to prevent recurrence of heterotopic ossification (HO). Materials and Methods: Forty-five patients with HO underwent surgical intervention and postoperative radiotherapy of the elbow. The median age of the patients was 29 years ($16{\sim}75$ years), and 27 of the patients were men and 18 were women. The occurrence of HO was mainly due to surgery after fracture (24/45) and traumatic injury (21/45). Limitation of the range of motion (ROM) was the most common symptom of the patients. Thirty-four patients received postoperative radiotherapy with a dose of 8 Gy in 2 fractions; 5 patients received a dose of 10 Gy in 5 fractions and 6 patients received a dose of 7 Gy in 1 fraction. Postoperative radiotherapy was given on the first two postoperative days for most of the patients. Sixteen patients were not given anti-inflammatory medication and 29 patients were given NSAIDs for $1{\sim}8$ months. Results: After a median follow-up period of 18 months (range $6{\sim}72$ months), 41 patients showed clinical improvement and two patients did not show improvement. Assessment of the ROM showed a mean improvement from $0{\sim}135^{\circ}$ to $60{\sim}145^{\circ}$ (p=0.028), and assessment of the functional outcome according to MEPI was from ($15{\sim}95$) to ($80{\sim}100$) (p<0.0001). Two of the 34 patients that were followed-up with radiography had mild radiological recurrence of heterotopic ossification. No complications were observed after the radiotherapy. Conclusion: These results suggested that low-dose radiation administered after surgical intervention is safe and effective to prevent the recurrence of HO in the elbow.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.1
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• pp.1-15
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• 2015

Impacts of Sea Surface Temperature (SST) assimilation to the prediction of upper ocean temperature is investigated by using a regional ocean forecasting system, in which 3-dimensional optimal interpolation is applied. In the present study, Sea Surface Temperature and Sea Ice Analysis (OSTIA) dataset is adopted for the daily SST assimilation. This study mainly compares two experimental results with (Exp. DA) and without data assimilation (Exp. NoDA). When comparing both results with OSTIA SST data during Sept. 2011, Exp. NoDA shows Root Mean Square Error (RMSE) of about $1.5^{\circ}C$ at 24, 48, 72 forecast hour. On the other hand, Exp. DA yields the relatively lower RMSE of below $0.8^{\circ}C$ at all forecast hour. In particular, RMSE from Exp. DA reaches $0.57^{\circ}C$ at 24 forecast hour, indicating that the assimilation of daily SST (i.e., OSTIA) improves the performance in the early SST prediction. Furthermore, reduction ratio of RMSE in the Exp. DA reaches over 60% in the Yellow and East seas. In order to examine impacts in the shallow costal region, the SST measured by eight moored buoys around Korean peninsula is compared with both experiments. Exp. DA reveals reduction ratio of RMSE over 70% in all season except for summer, showing the contribution of OSTIA assimilation to the short-range prediction in the coastal region. In addition, the effect of SST assimilation in the upper ocean temperature is examined by the comparison with Argo data in the East Sea. The comparison shows that RMSE from Exp. DA is reduced by $1.5^{\circ}C$ up to 100 m depth in winter where vertical mixing is strong. Thus, SST assimilation is found to be efficient also in the upper ocean prediction. However, the temperature below the mixed layer in winter reveals larger difference in Exp. DA, implying that SST assimilation has still a limitation to the prediction of ocean interior.

• Pediatric Infection and Vaccine
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• v.12 no.1
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• pp.67-74
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• 2005

Purpose : The incidence of mortality associated with respiratory difficulties is decreasing nowadays contributed to the development of neonatology. However, complications associated with mechanical ventilator are increasing. This study is to determine clinical manifestations, diagnositc availability of the endotracheal tip culture in patients with Ventilator-Associated Pneumonia(VAP) in neonatal intensive care unit(NICU). Methods : A retrospective analysis of 50 neonates who were admitted to the NICU of Kangnam Sacred Heart Hospital and had given mechanical ventilator from 1 January 2000 to 30 June 2003. VAP group defined as neonates who had pneumonia with mechanical ventilation longer than 48 hours. They were classified into VAP group(n=13) and control group (n=37) and the prevalence, microorganisms cultured from the endotracheal tube tip and risk factors were investigated. Results : The prevalence of VAP was 26.0%(n=13) and the most dominant microorganism cultured in our NICU was methicillin-resistant coagulase negative staphylococcus(MR-CNS) in 4 cases. Other microorganisms were Pseudomonas, Enterobacter, methicillin-resistant Staphylococcus aureus(MRSA) and Klebsiella. Gestational age, birth weight, Apgar score, respiratory distress syndrome, retinopathy of prematurity, bronchopulmonary dysplasia, sepsis, renal failure, pulmonary hemorrhage, pneumothorax were not different significantly between two groups except intraventricular hemorrhage(P<0.001) and patent ductus arteriosus(P<0.05). Duration of hospital stay and mortality rate were also not different significantly. Conclusion : VAP occurred at a significant rate among mechanically ventilated NICU patients. Despite of limitation of encotracheal tip culture, the most common microorganism was MR-CNS. We should be aware of occurrence of VAP in NICU neonate who were with mechanical ventilator and should treat with great care.

• Asia pacific journal of information systems
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• v.17 no.2
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• pp.97-122
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• 2007

Conventional networking and telecommunications infrastructure characterized by wires, fixed location, and inflexibility is giving way to mobile technologies. Numerous research reports point to the ultimate domination of wireless communication. With the increasing prevalence of advanced cell-phones, various mobile data services (hereafter MDS) are gaining popularity. Although cellular networks were originally introduced for voice communications, statistics indicate that data services are replacing the matured voice service as the growth engine for telecom service providers. For example, SK Telecom, the Korea's largest mobile service provider, reported that 25.6% of revenue and 28.5% of profit came from MDS in 2006 and the share is growing. Statistics also indicate that, in 2006, the average revenue per user (ARPU) for voice didn't change but MDS grew seven percents from the previous year, further highlighting its growth potential. MDS is defined "as an assortment of digital data services that can be accessed using a mobile device over a wide geographic area." A variety of MDS have been deployed, with a few reaching the status of killer applications. Many of them need to access the Internet through the cellular-phone infrastructure. In the past, when the cellular network didn't have acceptable bandwidth for data services, SMS (short messaging service) dominated MDS. Now, Internet-ready, next-generation cell-phones are driving rich digital data services into the fabric of everyday life, These include news on various topics, Internet search, mapping and location-based information, mobile banking and gaming, downloading (i.e., screen savers), multimedia streaming, and various communication services (i.e., email, short messaging, messenger, and chaffing). The huge economic stake MDS has on its stakeholders warrants focused research to understand associated dynamics behind its adoption. Lyytinen and Yoo(2002) pointed out the limitation of traditional adoption models in explaining the rapid diffusion of innovations such as P2P or mobile services. Also, despite the increasing popularity of MDS, unexpected drop in its usage is observed among some people. Intrigued by these observations, an exploratory study was conducted to examine decision factors of MDS usage. Data analysis revealed that the increase and decrease of MDS use was influenced by different forces. The findings of the exploratory study triggered our confirmatory research effort to validate the uni-directionality of studied factors in affecting MDS usage. This differs from extant studies of IS/IT adoption that are largely grounded on the assumption of bi-directionality of explanatory variables in determining the level of dependent variables (i.e., user satisfaction, service usage). The research goal is, therefore, to examine if increase and decrease in the usage of MDS are explained by two separate groups of variables pertaining to information quality and system quality. For this, we investigate following research questions: (1) Does the information quality of MDS increase service usage?; (2) Does the system quality of MDS decrease service usage?; and (3) Does user motivation for subscribing MDS moderate the effect information and system quality have on service usage? The research questions and subsequent analysis are grounded on the two factor theory pioneered by Hertzberg et al(1959). To answer the research questions, in the first, an exploratory study based on 378 survey responses was conducted to learn about important decision factors of MDS usage. It revealed discrepancy between the influencing forces of usage increase and those of usage decrease. Based on the findings from the exploratory study and the two-factor theory, we postulated information quality as the motivator and system quality as the de-motivator (or hygiene) of MDS. Then, a confirmative study was undertaken on their respective role in encouraging and discouraging the usage of mobile data service.

• Journal of Korean Society on Water Environment
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• v.18 no.3
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• pp.303-312
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• 2002

Polly-pigs technique was developed to remove internal rusts and scales from service pipes in the building by using Polly-pigs that were used as various applications in conventional plant pipelines. Results of cleaning experiments on 15mm GSP(Galvanic Steel Pipe) showed that hydraulic cross sectional area was more increased from 3.5% to 15.4% for straight part or elbow parts of several test pieces. Results of optical analysis also showed that rust and scale removed mostly by KDP series(only consisted of Polyurethane) were outside red colored scale ($Fe_2O_3{\cdot}H_2O$), and there was a limitation to the removal of black colored scale($Fe_2O{\cdot}nH_2O$) that was below red colored scale. But it was evaluated that KDPS series coated fine sand with KDP series could remove not only red colored scale but also black colored scale and more increase hydraulic cross sectional areas of 15mm GSP old service pipes from 13.0% to 17.9%. After KDPS series cleaning, hydraulic cross sectional areas of them were recovered from 95.9% to 99.5%. Turning force of Polly-pigs was largely improved by the effect of Helical guide vane(Cleaning v/v) and Rotating wing(Pigs), and the number of pig rotating also more increased sixteen times compared with conventional cleaning system without Helical guide vane and Rotating wing. After KDPC series cleaning of 100mm GSP old service pipes that hydraulic cross sectional areas were 90%, hydraulic cross sectional areas were almost recovered perfectly like new service pipes. Additionally pressure necessary to run Polly-pigs m 100mm GSP was lower and cleaning efficiency also was higher than 15mm GSP cleaning. Therefore it was thought that as the diameter of pipe was more increased, pressure necessary to clean service pipes was more decreased and cleaning efficiency was more increased in Polly-pigs cleaning.