• The KIPS Transactions:PartC
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• v.14C no.5
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• pp.417-424
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• 2007

Mesh networks using WLAN technology have been paid attention as a key wireless access technology. However, many technical issues still exist for its successful deployment. One of those issues is the routing problem that addresses the path setup through a WLAN mesh network for the data exchanges between a station and a wired network. Since the characteristics of a WLAN mesh network can be very dynamic, the use of single routing protocol would not fit for all environments whether it is reactive or proactive. Therefore, it is required to develop an adaptive routing protocol that modifies itself according to the changes in the network parameters. As a logical first step for the development, an analytical model considering all the dynamic features of a WLAN mesh network is required to evaluate the performance of a reactive and a proactive routing scheme. In this paper, we propose an analytical model that makes us scrutinize the impact of the network and station parameters on the performance of each routing protocol. Our model includes the size of a mesh network, the density of stations, mobility of stations. and the duration of network topology change. We applied our model to the AODV that is a representative reactive routing protocol and DSDV that is a representative proactive routing protocol to analyze the tradeoff between AODV and DSDV in dynamic network environments. Our model is expected to help developing an adaptive routing protocol for a WLAN mesh network.

• Journal of Chest Surgery
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• v.42 no.6
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• pp.744-748
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• 2009

Background: This study was designed to determine etiologic factors for iatrogenic pneumothorax in an era of in-creased use of invasive procedures and to evaluate its impact on morbidity. Material and Method: Subjects were 112 patients (65 men and 47 women ranging in age from 20 to 90 years) who were diagnosed with an iatrogenic pneumothorax between January 2005 and December 2008. We reviewed medical records retrospectively. Result: The leading causes of iatrogenic pneumothorax were percutaneous needle aspiration (50), central venous catheterization (29), acupuncture (14), thoracentesis (8) and positive pressure ventilation (7). The majority of the patients (60 of 114) were treated with chest tubes. The mean duration of hospital treatment was 5.8 $({\pm}4.0)$ days. Hospitalization was prolonged in 24 patients (21.1%). No patient died from iatrogenic pneumothorax. Conclusion: In our study, the most common cause of Iatrogenic pneumothorax was percutaneous needle aspiration. The mortality and morbidity from iatrogenic pneumothorax is not significant. The recognition of pneumothorax, depends on careful examination after completion of an invasive procedure, and should be followed by prompt and definitive therapy.

• Journal of Chest Surgery
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• v.47 no.3
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• pp.233-239
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• 2014

Background: As hypertrophied myocardium predisposes the patient to decreased tolerance to ischemia and increased reperfusion injury, myocardial protection is of utmost importance in patients undergoing aortic valve replacement (AVR) for severe aortic valve stenosis (AS). Methods: Consecutive 314 patients (mean age, $62.5{\pm}10.8$ years; 143 females) with severe AS undergoing isolated AVR were included. Postoperative myocardial injury (PMI) was defined as 1) maximum postoperative creatinine kinase isoenzyme MB or troponin-I levels ${\geq}10$ times of reference, 2) postoperative low cardiac output syndrome or episodes of ventricular arrhythmia, or 3) left ventricular ejection fraction of less than 55% and decrease in left ventricle (LV) ejection fraction of more than 20% of the baseline value. Results: There were 90 patients (28.7%) who developed PMI. There were five cases of early death (1.6%), all of whom had PMI. On multivariable analysis, the use of histidine-tryptophan-ketoglutarate (HTK) solution instead of blood cardioplegia (odds ratio [OR], 3.06; 95% confidence interval [CI], 1.63 to 5.77; p=0.001), greater LV mass (OR, 1.04; 95% CI, 1.01 to 1.07; p=0.007), and increased cardiac ischemic time (OR, 1.13; 95% CI, 1.05 to 1.22; p<0.001) were independent predictors for PMI. Patients who had PMI showed significantly inferior long-term survival than those without PMI (p=0.049). Conclusion: PMI occurred in a considerable proportion of patients undergoing AVR for severe AS and was associated with poor long-term survival. HTK cardioplegia, higher LV mass, and longer cardiac ischemic duration were suggested as predictors of myocardial injury.

• Journal of Internet Computing and Services
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• v.15 no.2
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• pp.87-94
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• 2014

Social media which includes Facebook enable users to construct relationships and networks as well as sharing of information. By enlisting Facebook users as proxy, this paper attempted to analyze the different emotional states experienced by social media users, specifically to gauge what effect their usage motivation and usage pattern had on the ambivalence level of the users. The quantitative survey result revealed that usage duration or the time of day when Facebook was accessed had no relevant impact on one's ambivalence level. However, there was a direct correlation between frequency of Facebook usage and the ambivalence level. The more the user logged onto Facebook the more suppressed his or her expression became due to fear of giving negative impressions to others and also receiving their negative feedbacks, which then subsequently added to the user's ambivalence. People's main reasons for using Facebook were identified as "chatting," "communicating," "maintaining relationships," "relationship building," "networking," and "finding information about friends," but only "maintaining relationships," "communicating," and "networking" had observable effect on ambivalence. There were no noticeable differences among genders with regards to ambivalence and usage levels, but there was a marked difference based on the user's age. For example, people in their forties showed higher levels of ambivalence than those in their twenties. This may be attributed to anxiety they face as they use Facebook primarily to expand their networks and to maintain relationships. As such, it is surmised that their fatigue level from using social media will only increase. Meanwhile, Korean Facebook user's emotional manifestation tended to skew toward relation-involved ambivalence rather than the self-defensive type. This relation-involved ambivalence might be something that can actually help prevent damage to relationships by limiting excessive emotional expressions. In other words, such ambivalence by Facebook users may be a positive element in a user's social media interaction.

• Journal of Korean Neurosurgical Society
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• v.30 no.sup2
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• pp.221-227
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• 2001

Objective : The therapeutic impact of tumor resection in glioblastomas is poorly defined and still questionable. Therefore, we conducted the current study to verify the role of tumor resection in the treatment of these highly malignant tumors. Methods : A retrospective study was performed(1990-1999) to compare the treatment results of surgical resection plus radiotherapy(130 patients) with those of stereotactic biopsy plus radiotherapy(19 patients) in glioblastomas. Only adult patients with supratentorial, de novo glioblastoma located in one lobe were included. Survival time/rate was analysed with Kaplan-Meier method, and prognostic variables were obtained from the univariate log-rank test and the multivariate Cox's proportional hazards model. Results : The resection group and the biopsy group did not differ in terms of age, gender, duration of symptoms, presenting symptoms, tumor location, tumor side, tumor size, and the frequency of midline shift. Patients in the biopsy group more often were found to have worse preoperative Karnofsky performance status(KPS)(p=0.001). On univariate analysis, age, KPS, and tumor side were associated with survival(p=0.0053, 0.0001, and 0.0331 respectively). Median survival time and 1-year survival rate were also statistically improved by tumor resection ; resection group - 13 months and 61.2%, and biopsy group - 8 months and 19.7%, respectively(p=0.0001). In patients with midline shift of the tumor, resection was highly effective comparing to biopsy(p=0.0001), but in patients without midline shift, external beam radiation alone was as effective as tumor resection(p=0.0605). Other prognostic variables did not affect survival. On multivariate analysis after variable selection, survival was independently associated with KPS(p=0.001), but not the surgical resection(p=0.2837). Even in biopsy group with midline shift of the tumor, survival rate was not different from that seen after tumor resection(p=0.3505). Conclusions : Radiotherapy alone was as effective as tumor resection plus radiotherapy in patients without midline shift of the tumor. Although there was not statistically significant, tumor resection looked like effective in patients with midline shift. For supratentorial, lobar glioblastoma patients without mass effect of the tumor, biopsy with radiotherapy is one of rational treatment strategies. We consider that tumor resection should be performed in patients with pretreatment midline shift.

• Journal of the Korean Child Neurology Society
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• v.26 no.4
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• pp.221-226
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• 2018

Purpose: Febrile seizures (FSs) are the most common type of seizure in the first 5 years of life and are frequently associated with viral infections. Influenza infection is associated with a variety of neurological conditions, including FSs. The purpose of this study was to evaluate the clinical implications of influenza infection in FSs. Methods: In total, 388 children with FS were divided into two groups: FS with influenza infection (n=75) and FSs without influenza infection (n=313). Their medical records, including seizure type, frequency, duration, and familial history of FSs or epilepsy, were retrospectively reviewed and the clinical characteristics of the two groups were compared. Results: In total, 75 of the 388 children (19.3%) had FSs associated with influenza infection; such children were significantly older than those with FSs without influenza infection ($34.9{\pm}22.3$ months vs. $24.4{\pm}14.2$ months; P<0.001). The children who had more than two febrile seizures episodes were more prevalent in children with FS with influenza infection [40/75 (53.3%) vs. 92/313 (29.4%); P<0.01]. Children older than 60 months were more likely to have influenza infection compared to those aged less than 60 months [11/22 (50%) vs. 64/366 (17.5%); P=0.001]. Conclusion: Influenza infection may be associated with FSs in older children, and with recurrence of FSs. Its role in the development of afebrile seizures or subsequent epilepsy requires further investigation with long-term follow-up.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.425-432
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• 2019

This study examined the effects of livestock disease news, such as foot-and-mouth disease (FMD), collected by the Korea Press Foundation on BIGKinds on the consumption of beef and pork. The consumer purchase data were obtained from the Rural Development Administration's Agrifood consumer panel data. Survival analysis showed that the FMD news noted beef and pork, and the first purchase rate decreased due to FMD news. The time-dependent Cox proportional hazards model revealed all models to be significant. FMD news was significant in each model. In 2010, the Hazard Ratio of domestic and imported pork was 0.999, and the first purchase rate decreased 0.999 times for each additional FMD news item. On the other hand, the Hazard Ratio of pork in 2015 was 1.001, and the first purchase rate increased. In the case of beef, results similar to pork were shown. This study estimated the impact of consumer meat consumption disease news on the first purchases according to origin and meat. These results provide the necessary information for rational production and consumption activities. In addition, it can also be used for promotion by estimating the duration of livestock disease news.

• Korean Circulation Journal
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• v.48 no.11
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• pp.1002-1011
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• 2018

Background and Objectives: The prognostic impact of left axis deviation (LAD) on clinical outcomes in acute heart failure syndrome (AHFS) with left bundle branch block (LBBB) is unknown. The aim of this study was to determine the prognostic significance of axis deviation in acute heart failure patients with LBBB. Methods: Between March 2011 and February 2014, 292 consecutive AHFS patients with LBBB were recruited from 10 tertiary university hospitals. They were divided into groups with no LAD (n=189) or with LAD (n=103) groups according to QRS axis <-30 degree. The primary outcome was all-cause mortality. Results: The median follow-up duration was 24 months. On multivariate analysis, the rate of all-cause death did not significantly differ between the normal axis and LAD groups (39.7% vs. 46.6%, adjusted hazard ratio, 1.01; 95% confidence interval, 0.66, 1.53; p=0.97). However, on the multiple linear regression analysis to evaluate the predictors of the left ventricular ejection fraction (LVEF), presence of LAD significantly predicted a worse LVEF (adjusted beta, -3.25; 95% confidence interval, -5.82, -0.67; p=0.01). Right ventricle (RV) dilatation was defined as at least 2 of 3 electrocardiographic criteria (late R in lead aVR, low voltages in limb leads, and R/S ratio <1 in lead V5) and was more frequent in the LAD group than in the normal axis group (p<0.001). Conclusions: Among the AHFS with LBBB patients, LAD did not predict mortality, but it could be used as a significant predictor of worse LVEF and RV dilatation (Trial registry at KorAHF registry, ClinicalTrial.gov, NCT01389843).

• Journal of Oriental Neuropsychiatry
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• v.30 no.3
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• pp.251-263
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• 2019

Objectives: The purpose of this study was to review the clinical research trends in the treatment of post traumatic stress disorder (PTSD) in Korean medicine (KM). Methods: We searched MEDLINE, CENTRAL, EMBASE, Google Scholar and five Korean databases through May 2019, for studies on KM to treat PTSD. Clinical research that conducted KM treatment of PTSD patients were included. Two researchers independently conducted study selection and data extraction process. Results: Totally, eight studies were included in this review. Types of traumatic events that patients experienced included physical violence/threatening, traffic accidents, sexual violence and personal tragic events. KM interventions performed included acupuncture, moxibustion, herbal medicine, physical therapy, and KM-based psychotherapy. Treatment duration varied from two days to more than five months. Follow-up began at least one week to three months after the end of treatments. It was reported that the major psychological and/or somatic symptoms of PTSD, such as anxiety, depression, insomnia, and musculoskeletal pain, subjectively improved, as well as other objective outcomes: Impact Event Scale-Revised Korean version (IES-R-K), Beck's Depression Inventory (BDI), State-Trait Anxiety Inventory, Hwabyung Symptoms/characters, Electroencephalography (EEG) change, etc. Statistical studies were conducted in three studies only. Outcomes such as Visual Analogue Scale (VAS), BDI, and IES-R-K showed statistically significant improvement after KM treatments. There was no study reporting adverse events during or after the interventions. Conclusions: According to this review, diverse types of KM treatments have been used among PTSD patients in eight studies. The KM treatments effectively improved psychological and somatic symptoms of PTSD patients. However, the lack of high quality research as well as the lack of standardization of KM treatments for PTSD are limitations. Further methodologically robust clinical trials should be performed, and the standardization of KM treatments for PTSD should be sought.

• Informatization Policy
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• v.26 no.1
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• pp.3-24
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• 2019

This study examined the trends and issues of social media campaign studies from three aspects-campaign strategy, institutional environment regulating the social media, and political effect. Then, this study performed an empirical analysis on the case of the 20th general election in order to discuss the political effect, which has been analyzed the least. Specifically, this study empirically examined the trends of candidates' participation in the twitter campaign, the partial mobilization and voter response, and the platform effect on the election results. The study examined all of the candidates' twitter accounts and traffic and found the following results.-first, the number of participants in the twitter campaign increased significantly compared to the 19th general election, and the campaign was dominated by only two political parties that had more power to mobilize resources; second, it was clearly identified that twitter is a partisan media. where specifically, those in the mainstream of the Democratic Party mobilized much more supporters; and lastly, the twitter campaign has a positive impact on the increase in the rate of votes and chances of winning the election. Particularly, the number of followers and the duration of activities were found statistically meaningful, proving that promotion of networking and social capital is more important in election campaigns.