• Journal of Intelligence and Information Systems
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• v.27 no.3
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• pp.57-73
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• 2021

Maintenance and prevention of failure through anomaly detection of ICT infrastructure is becoming important. System monitoring data is multidimensional time series data. When we deal with multidimensional time series data, we have difficulty in considering both characteristics of multidimensional data and characteristics of time series data. When dealing with multidimensional data, correlation between variables should be considered. Existing methods such as probability and linear base, distance base, etc. are degraded due to limitations called the curse of dimensions. In addition, time series data is preprocessed by applying sliding window technique and time series decomposition for self-correlation analysis. These techniques are the cause of increasing the dimension of data, so it is necessary to supplement them. The anomaly detection field is an old research field, and statistical methods and regression analysis were used in the early days. Currently, there are active studies to apply machine learning and artificial neural network technology to this field. Statistically based methods are difficult to apply when data is non-homogeneous, and do not detect local outliers well. The regression analysis method compares the predictive value and the actual value after learning the regression formula based on the parametric statistics and it detects abnormality. Anomaly detection using regression analysis has the disadvantage that the performance is lowered when the model is not solid and the noise or outliers of the data are included. There is a restriction that learning data with noise or outliers should be used. The autoencoder using artificial neural networks is learned to output as similar as possible to input data. It has many advantages compared to existing probability and linear model, cluster analysis, and map learning. It can be applied to data that does not satisfy probability distribution or linear assumption. In addition, it is possible to learn non-mapping without label data for teaching. However, there is a limitation of local outlier identification of multidimensional data in anomaly detection, and there is a problem that the dimension of data is greatly increased due to the characteristics of time series data. In this study, we propose a CMAE (Conditional Multimodal Autoencoder) that enhances the performance of anomaly detection by considering local outliers and time series characteristics. First, we applied Multimodal Autoencoder (MAE) to improve the limitations of local outlier identification of multidimensional data. Multimodals are commonly used to learn different types of inputs, such as voice and image. The different modal shares the bottleneck effect of Autoencoder and it learns correlation. In addition, CAE (Conditional Autoencoder) was used to learn the characteristics of time series data effectively without increasing the dimension of data. In general, conditional input mainly uses category variables, but in this study, time was used as a condition to learn periodicity. The CMAE model proposed in this paper was verified by comparing with the Unimodal Autoencoder (UAE) and Multi-modal Autoencoder (MAE). The restoration performance of Autoencoder for 41 variables was confirmed in the proposed model and the comparison model. The restoration performance is different by variables, and the restoration is normally well operated because the loss value is small for Memory, Disk, and Network modals in all three Autoencoder models. The process modal did not show a significant difference in all three models, and the CPU modal showed excellent performance in CMAE. ROC curve was prepared for the evaluation of anomaly detection performance in the proposed model and the comparison model, and AUC, accuracy, precision, recall, and F1-score were compared. In all indicators, the performance was shown in the order of CMAE, MAE, and AE. Especially, the reproduction rate was 0.9828 for CMAE, which can be confirmed to detect almost most of the abnormalities. The accuracy of the model was also improved and 87.12%, and the F1-score was 0.8883, which is considered to be suitable for anomaly detection. In practical aspect, the proposed model has an additional advantage in addition to performance improvement. The use of techniques such as time series decomposition and sliding windows has the disadvantage of managing unnecessary procedures; and their dimensional increase can cause a decrease in the computational speed in inference.The proposed model has characteristics that are easy to apply to practical tasks such as inference speed and model management.

• Tuberculosis and Respiratory Diseases
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• v.46 no.4
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• pp.564-573
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• 1999

Background: With variable symptoms and nonspecific radiographic appearances, pulmonary embolism (PE) is a frequent and often undiagnosed cause of mortality and morbidity. The Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study suggested that the majority of patients undergoing ventilation-perfusion (V-Q) scan would require additional studies to establish or to exclude the diagnosis of PE. Pulmonary angiography has been regarded as gold standard for diagnosis of PE. However, it is an invasive procedure that may be associated with significant notable morbidity and mortality. Thus, availability of an accurate, noninvasive screening examination is highly desirable. Method: From October 1994 to February 1997, twenty patients (male 13, female 7, range 23-91 years, median 58 years) who were suspected as pulmonary embolism on the basis of clinical evidence and underwent the spiral volumetric computed tomography (spiral CT), were studied retrospectively to evaluate the effectiveness of spiral CT as a diagnostic tool in PE. Results: PE could be excluded with spiral CT in 4 patients ; diagnoses of these patients were lung cancer, pneumonia with lung abscess, bilateral pleural effusion due to congestive heart failure, nonspecific pulmonary abnormality retrospectively. One patient who disclosed high probability in V/Q scan, could be diagnosed as pneumonia with lung abscess and underlying emphysema with spiral CT. Among 4 patients who showed intermediate and low probability in V/Q scan, 3 patients could be confirmed as PE with spiral CT. Spiral CT was helpful in 3 patients, in whom V/Q scan could not be performed due to other reasons (e.g. night time, mechanical ventilation) to confirm the diagnosis of PE. Spiral CT could demonstrate embolus above lobar artery level in 11 patients, and up to segmental artery level in 5 patients. Conclusion: This study demonstrated that spiral CT could allow accurate demonstration of thrombotic clots in centrally localized embolism. Spiral CT could be effective, specific, noninvasive and useful diagnostic screening modality for the diagnosis of pulmonary embolism.

• Tuberculosis and Respiratory Diseases
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• v.59 no.5
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• pp.473-479
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• 2005

Background : A pulmonary embolism often presents with nonspecific symptoms and signs. However, a delayed diagnosis can result in catastrophic outcome. The majority of preventable deaths associated with a pulmonary embolism can be ascribed to a missed diagnosis rather than to the failure of existing treatments. Therefore, accurate and rapid diagnostic methods are essential for the management of a pulmonary embolism. The recent generation of multidetector-row spiral CT scanners appears to outperform other imaging modalities in detecting a central and peripheral pulmonary embolism. However, there are some variations in the interpretations of the findings between observers. This study examined the inter-observer differences of the diagnoses in patients with a pulmonary embolism. Method : 64 patients who were diagnosed with a pulmonary embolism either clinically or with spiral chest CT from 2002 to 2004, were included. Two thoracic radiologists interpreted the multidetector-row spiral CT in terms of the diagnosis of a pulmonary embolism and the location of the thrombus independently. Among 64 patients, 14 patients were excluded because there was no evidence of a pulmonary embolism or there was different interpretation of the pulmonary embolism between radiologists. A clinical diagnosis was based on "Rules for predicting the probability of embolism". Results : The mean score of the patients according to the Wells method was $3.91{\pm}0.30$ (0-9). The accordance of the radiologists was 95% in the main, 85% in the lobar, 91.2% in the segmental, and 96% in the sub-segmental pulmonary arteries. After excluding the negative interpretation from both radiologists, their agreement was 76.2%(${\kappa}.$ 0.83) in the main, 57.6%(${\kappa}.$ 0.63) in the lobar, 51.5%(${\kappa}.$ 0.63) in the segmental, and 34.6%(${\kappa}.$ 0.49) in the sub-segmental pulmonary arteries. Conclusion : Chest CT has been recently applied to patients suspected of having a pulmonary embolism. It was found that spiral CT is a rapid test for diagnosing a thrombus, and there was reliable accordance between the observers from the area of the large pulmonary arteries. However, there was a lack of agreement between the observers in diagnosing thrombi located distal to the sub-segmental arteries.

• Pediatric Infection and Vaccine
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• v.18 no.2
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• pp.109-116
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• 2011

Purpose : Pneumococcus is one of the most important causes of invasive infection through the childhood period. In January 2008, the Clinical and Laboratory Standards Institute (CLSI) published revised penicillin breakpoints for Streptococcus pneumoniae and penicillin susceptibility rates of S. pneumoniae increased in Korea. This study was performed to determine the probability of oral amoxicillin for the empirical treatment achieving bactericidal exposure against pneumococcus using pharmacodynamics model. Methods : Twenty-three isolates of pneumococci were subjected to determine minimum inhibitory concentration (MIC) for ${\beta}$-lactams and macrolide. For the ${\beta}$-lactams, exposure of fT >MIC (time that free drug concentrations remain above the MIC) for 50% of the administration interval have determined the probability of target attainment (PTA), and regimens that had a PTA >90% were considered optimal. An analysis was performed by applying MIC of 23 isolates to a 5000-patient Monte Carlo simulation model. Results : Among 23 isolates from healthy children, 7 (30.4%) isolates were MIC ${\leq}$1.0 ${\mu}g$/mL and 19 (82.6%) were MIC ${\leq}$2 ${\mu}g$/mL for amoxicillin. Amoxicillin 40 mg/kg/day achieved PTA >90% at MIC ${\leq}$1.0 ${\mu}g$/mL but PTA decreased to 52% at MIC 2 ${\mu}g$/mL, whereas amoxicillin 90 mg/kg/day can predict 97% of PTA at MIC 2 ${\mu}g$/mL. Overall, oral amoxicillin 90 mg/ kg/day for the empirical treatment against pneumococcus can expect more successful response in Korean children. Conclusion : Considering the resistantce pattern of pneumococci in Korean children, we estimate that oral amoxicillin 90 mg/kg/day will provide a pharmacodynamic advantage for the empirical treatment against pneumococcus. And low dose amoxicillin or macrolide are expected to have higher chance of treatment failure than high dose oral amoxicillin.

• Radiation Oncology Journal
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• v.25 no.4
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• pp.213-218
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• 2007

Purpose: To analyze retrospectively the outcome of postoperative radiation therapy with or without concurrent chemotherapy for curatively resected stage II pancreatic cancer with T3 or N1 disease. Materials and Methods: Between January 1996 and December 2005, twenty-eight patients completed adjuvant radiation therapy at Ajou University Hospital. The patients had either pathologic T3 stage or N1 stage. The radiation target volume encompassed the initial tumor bed identified preoperatively, resection margin area and celiac nodal area. In the case of N1 patients, the radiation field extended to the lower margin of the L3 vertebra for covering both para-aortic lymph nodes bearing area. The median total radiation dose was 50 Gy. Ten patients received concurrent chemotherapy. Results: Thirteen patients (46%) showed loco-regional recurrences. The celiac axis nodal area was the most frequent site (4 patients). Five patients showed both loco-regional recurrence and a distant metastasis. Patients with positive lymph nodes had a relatively high probability of a distant metastasis (57.1%). Patients that had a positive resection margin showed a relatively high local failure rate (57.1%). The median disease-free survival period of all patients was 6 months and the 1-and 2-year disease free survival rates were 27.4% and 8.2%, respectively. The median overall survival period was 9 months. The 2-and 3-year overall survival rates were 31.6% and 15.8%, respectively. Conclusion: The pancreatic cancer patients with stage II had a high risk of local failure and a high risk of a distant metastasis. We suggest the concurrent use of an effective radiation-sensitizing chemotherapeutic drug and adjuvant chemotherapy after postoperative radiation therapy for the treatment of patients with stage II pancreatic cancer.

• Journal of Korea Water Resources Association
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• v.56 no.6
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• pp.419-429
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• 2023

The objective of this study was to determine the management water level of an estuary reservoir considering three aspects: the water use, flood control and water quality, and to use a robust decision-making to consider uncertainty due to climate change. The watershed-reservoir linkage model was used to simulate changes in inflow due to climate change, and changes in reservoir water level and water quality. Five management level alternatives ranging from -1.7 El.m to 0.2 El.m were evaluated under the SSP1, 2, 3, and 5 scenariosof the ACCESS-CM2 Global Climate Model. Performance indicators based on period-reliability were calculated for robust decision-making considering the three aspects, and regret was used as a decision indicator to identify the alternatives with the minimum maximum regret. Flood control failure increased as the management level increased, while the probability of water use failure increased as the management level decreased. The highest number of failures occurred under the SSP5 scenario. In the water quality sector, the change in water quality was relatively small with an increase in the management level due to the increase in reservoir volume. Conversely, a decrease in the management level resulted in a more significant change in water quality. In the study area, the estuary reservoir was found to be problematic when the change in water quality was small, resulting in more failures.

• Radiation Oncology Journal
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• v.21 no.4
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• pp.253-260
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• 2003

Purpose: No general consensus has been reached regarding the necessity of postoperative radiation therapy (PORT) and the optimal techniques of its application for patients with chest wall invasion (pT3cw) and node negative (NO) non-small cell lung cancer (NSCLC). We retrospectively analyzed the PT3cwN0 NSCLC patients who received PORT because of presumed inadequate resection margin on surgical findings. Materials and Methods: From Aug. 1994 till June 2000, 21 pT3cwN0 NSCLC patients received PORT at Samsung Medical Center; all of whom underwent curative on-bloc resection of the primary tumor plus the chest wall and regional lymph node dissection. PORT was typically stalled 3 to 4 weeks after operation using 6 or 10 MV X-rays from a linear accelerator. The radiation target volume was confined to the tumor bed plus the immediate adjacent tissue, and no regional lymphatics were included. The planned radiation dose was 54 Gy by conventional fractionation schedule. The survival rates were calculated and the failure patterns analyzed. Results: Overall survival, disease-free survival, loco-regional recurrence-free survival, and distant metastases-free survival rates at 5 years were 38.8$\%$, 45.5$\%$, 90.2$\%$, and 48.1$\%$, respectively. Eleven patients experienced treatment failure: six with distant metastases, three with intra-thoracic failures, and two with combined distant and intra-thoracic failures. Among the five patients with intra-thoracic failures, two had pleural seeding, two had in-field local failures, and only one had regional lymphatic failure in the mediastinum. No patients suffered from acute and late radiation side effects of RTOG grade 3 or higher. Conclusion: The strategy of adding PORT to surgery to improve the probability, not only of local control but also of survival, was justified, considering that local control was the most important component in the successful treatment of pT3cw NSCLC patients, especially when the resection margin was not adequate. The incidence and the severity of the acute and late side effects of PORT were markedly reduced, which contributed to improving the patients' qualify of life both during and after PORT, without increasing the risk of regional failures by eliminating the regional lymphatics from the radiation target volume.

• Journal of Global Scholars of Marketing Science
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• v.19 no.4
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• pp.44-56
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• 2009

Impulse purchasing is defined as an immediate purchase with no pre-shopping intentions. Previous studies of impulse buying have focused primarily on factors linked to marketing mix variables, situational factors, and consumer demographics and traits. In previous studies, marketing mix variables such as product category, product type, and atmospheric factors including advertising, coupons, sales events, promotional stimuli at the point of sale, and media format have been used to evaluate product information. Some authors have also focused on situational factors surrounding the consumer. Factors such as the availability of credit card usage, time available, transportability of the products, and the presence and number of shopping companions were found to have a positive impact on impulse buying and/or impulse tendency. Research has also been conducted to evaluate the effects of individual characteristics such as the age, gender, and educational level of the consumer, as well as perceived crowding, stimulation, and the need for touch, on impulse purchasing. In summary, previous studies have found that all products can be purchased impulsively (Vohs and Faber, 2007), that situational factors affect and/or at least facilitate impulse purchasing behavior, and that various individual traits are closely linked to impulse buying. The recent introduction of new distribution channels such as home shopping channels, discount stores, and Internet stores that are open 24 hours a day increases the probability of impulse purchasing. However, previous literature has focused predominantly on situational and marketing variables and thus studies that consider critical consumer characteristics are still lacking. To fill this gap in the literature, the present study builds on this third tradition of research and focuses on individual trait variables, which have rarely been studied. More specifically, the current study investigates whether impulse buying tendency has a positive impact on impulse buying behavior, and evaluates how consumer characteristics such as the need for cognitive closure (NFCC), psychological wellbeing, and susceptibility to interpersonal influences affect the tendency of consumers towards impulse buying. The survey results reveal that while consumer affective impulsivity has a strong positive impact on impulse buying behavior, cognitive impulsivity has no impact on impulse buying behavior. Furthermore, affective impulse buying tendency is driven by sub-components of NFCC such as decisiveness and discomfort with ambiguity, psychological wellbeing constructs such as environmental control and purpose in life, and by normative and informational influences. In addition, cognitive impulse tendency is driven by sub-components of NFCC such as decisiveness, discomfort with ambiguity, and close-mindedness, and the psychological wellbeing constructs of environmental control, as well as normative and informational influences. The present study has significant theoretical implications. First, affective impulsivity has a strong impact on impulse purchase behavior. Previous studies based on affectivity and flow theories proposed that low to moderate levels of impulsivity are driven by reduced self-control or a failure of self-regulatory mechanisms. The present study confirms the above proposition. Second, the present study also contributes to the literature by confirming that impulse buying tendency can be viewed as a two-dimensional concept with both affective and cognitive dimensions, and illustrates that impulse purchase behavior is explained mainly by affective impulsivity, not by cognitive impulsivity. Third, the current study accommodates new constructs such as psychological wellbeing and NFCC as potential influencing factors in the research model, thereby contributing to the existing literature. Fourth, by incorporating multi-dimensional concepts such as psychological wellbeing and NFCC, more diverse aspects of consumer information processing can be evaluated. Fifth, the current study also extends the existing literature by confirming the two competing routes of normative and informational influences. Normative influence occurs when individuals conform to the expectations of others or to enhance his/her self-image. Whereas informational influence occurs when individuals search for information from knowledgeable others or making inferences based upon observations of the behavior of others. The present study shows that these two competing routes of social influence can be attributed to different sources of influence power. The current study also has many practical implications. First, it suggests that people with affective impulsivity may be primary targets to whom companies should pay closer attention. Cultivating a more amenable and mood-elevating shopping environment will appeal to this segment. Second, the present results demonstrate that NFCC is closely related to the cognitive dimension of impulsivity. These people are driven by careless thoughts, not by feelings or excitement. Rational advertising at the point of purchase will attract these customers. Third, people susceptible to normative influences are another potential target market. Retailers and manufacturers could appeal to this segment by advertising their products and/or services as products that can be used to identify with or conform to the expectations of others in the aspiration group. However, retailers should avoid targeting people susceptible to informational influences as a segment market. These people are engaged in an extensive information search relevant to their purchase, and therefore more elaborate, long-term rational advertising messages, which can be internalized into these consumers' thought processes, will appeal to this segment. The current findings should be interpreted with caution for several reasons. The study used a small convenience sample, and only investigated behavior in two dimensions. Accordingly, future studies should incorporate a sample with more diverse characteristics and measure different aspects of behavior. Future studies should also investigate personality traits closely related to affectivity theories. Trait variables such as sensory curiosity, interpersonal curiosity, and atmospheric responsiveness are interesting areas for future investigation.

• Journal of Chest Surgery
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• v.37 no.10
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• pp.845-855
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• 2004

Background: No general consensus has been available regarding the necessity of postoperative radiation therapy (PORT) and its optimal techniques in the patients with chest wall invasion (pT3cw) and node negative (N0) non-small cell lung cancer (NSCLC). We did retrospective analyses on the pT3cwN0 NSCLC patients who received PORT because of presumed inadequate resection margin on surgical findings. And we compared them with the pT3cwN0 NSCLC patients who did not received PORT during the same period. Material and Method: From Aug. of 1994 till June of 2002, 22 pT3cwN0 NSCLC patients received PORT-PORT (＋) group- and 16 pT3cwN0 NSCLC patients had no PORT-PORT (-) group. The radiation target volume for PORT (＋) group was confined to the tumor bed plus the immediate adjacent tissue only, and no regional lymphatics were included. The prognostic factors for all patients were analyzed and survival rates, failure patterns were compared with two groups. Result: Age, tumor size, depth of chest wall invasion, postoperative mobidities were greater in PORT (-) group than PORT (＋) group. In PORT (-) group, four patients who were consulted for PORT did not receive the PORT because of self refusal (3 patients) and delay in the wound repair (1 patient). For all patients, overall survival (OS), disease-free survival (DFS), loco-regional recurrence-free survival (LRFS), and distant metastases-free survival (DMFS) rates at 5 years were 35.3%, 30.3%, 80.9%, 36.3%. In univariate and multivariate analysis, only PORT significantly affect the survival. The 5 year as rates were 43.3% in the PORT (＋) group and 25.0% in PORT (-) group (p=0.03). DFS, LRFS, DMFS rates were 36.9%, 84.9%, 43.1 % in PORT (＋) group and 18.8%, 79.4%, 21.9% in PORT(-) group respectively. Three patients in PORT (-) group died of intercurrent disease without the evidence of recurrence. Few suffered from acute and late radiation side effects, all of which were RTOG grade 2 or lower. Conclusion: The strategy of adding PORT to surgery to improve the probability not only of local control but also of survival could be justified, considering that local control was the most important component in the successful treatment of pT3cw NSCLC patients, especially when the resection margin was not adequate. Authors were successful in the marked reduction of the incidence as well as the severity of the acute and late side effects of PORT, without taking too high risk of the regional failures by eliminating the regional lymphatics from the radiation target volume.

• International Commerce and Information Review
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• v.10 no.4
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• pp.457-491
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• 2008

As stage equipment export markets along with special lighting service lack the attraction for already globally established businesses, such markets can be viewed as an advantageous opportunity for SMEs as in general. In reality, global businesses tend to focus on large construction projects and this indicates relatively less substantial markets such as stage equipment and special lighting service export are more suitable for SME businesses. However, possible problems may be recognized as following; doubtful capabilities by such businesses to join in the vast and competitive global market and pursue manufacturing and service based export. This point is also supported by the fact that such in general SME businesses have substantially less experience in exporting products and services abroad. Realizing the distinctive features of the Korean economy, it is unarguable that every sector and area of global market must be regarded and monitored closely. Hence, it can be argued that there is an imminent need for establishment of supportive institution to assist export process of combination of stage equipments and special lighting service. This study emphasizes the need to improve export process of stage equipments, special lighting services as well as other related products and services which have been focused in domestic market only until now. Further, it also analyzed the potential prospect of such direction reconciling current crisis our manufacturing industry is facing. Even though it maybe regarded as one of the niche market for export of Korea in the short term view, stage equipment and special lighting service industry may rapidly grow as the global cultural industries have grown along with the increase of national income earnings overall. Due to such advantageous features, it can be expected that such industries will show strong growth in the near future. After analyzing the fact that Korea's plants (eg. powerplants) export sector is at its boom, there is a need to transform stage equipment and special lighting service export market into a primary market from a secondary(niche) market for SMEs. This study is viewed from the Korean economic and export sector aspect in the aim of seeking a solution to conquest our realistic limit in our export sector by developing a suitable export model. There have been cases of very few attempts to expand abroad by SMEs who have failed miserably due to their failure to adapt to foreign culture, practice and languages as well as substantial lack in experience in export marketing. Despite this, neglecting our manufacturing industry as it is which is showing its limit and problems is out of option therefore, it is imminent that we come up with an effective measure to address this problem and service export can be suggested as one of them. This study reveals manufacturing-service export model of stage equipment and special lighting service and its related areas is recognized as a field with a very strong future and furthermore, it is expected to bring synergy effects in manufacturing and services sector as well. Further, the operation strategy contains combination, composition and fusion(convergence) of manufacturing and service sectors which could derive various of export products which displays greater success probability or this export model. The outcome of this research is expected to become a useful source for enterprises related to such industry which are seeking a possible global expansion. Furthermore, it is also expected to become a catalyst which fastens the process of global expansion and not only that, we are firmly assured that this study will become an opportunity to improve our current policies and institutions related to this area's export market.