• 인터넷정보학회논문지
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• 제10권4호
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• pp.45-54
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• 2009

본 논문에서는 영상 내 객체들의 카테고리 분석을 위해 연구된 PLSA를 기반으로 특이점에 가중치를 부여하여 보다 유사한 카테고리 간에 인식 성능을 향상시키는 접근법에 대하여 연구하였다. PLSA는 문서기반의 정보검색 분야로부터 소개된 기법으로, 약한 수준의 비감독 방법임에도 불구하고 인상적인 인식성능을 보여준다. 그러나 비슷한 특징점 분포를 보이는 유사한 카테고리 간의 객체 카테고리 인식에 대해서는 비교적 낮은 성능을 보인다. 본 연구에서는 카테고리간의 비교실험을 통해 각 특징점에 대하여 가중치를 부여한 PLSA를 적용하여 유사한 객체 간의 카테고리 인식 가능성을 살펴보았다. 실험에서는 기존의 PLSA 기법과 제안한 가중치를 부여 PLSA 기법을 각각 적용하여 그 성능을 비교하였다. 본 연구에서는 기존 PLSA 기법에서는 비교적 낮은 인식률을 보인 유사한 카테고리 인식에 대하여 실험 결과를 통해 가중치를 부여한 PLSA 기법이 보다 향상된 성능을 보임을 확인하였다.

• 한국치위생학회지
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• 제4권1호
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• pp.15-29
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• 2004

The purpose of this study was to understand the relationship among knowledge, attitude, and behavior of dental personnel about the defense against dental radiation according to general features, and help them recognize the importance of defense against dental radiation. A questionnaire survey of 187 dental personnel who were working in 121 medical institutions such as university hospitals, general hospitals, hospitals, clinics, and public health centers in Seoul area was conducted from December 2002 to January 2003. Study findings are as follows: 1. The average knowledge score for the defense of radiation was 9.51(full score=14): By the demographic features, the know level for the defense of radiation was appeared to be different with the occupational category, age, academic background, workplace, year of working, and whether having the education of radiation or not. By questionnaire items, the knowledge for the defense of radiation was high in general, but for the item. 'the average amount of being bombed with radiation according occupations cannot be over 20mSv in a year for prescribed 5 years'. it was 18.7%: and for the item. 'the longer the length between focus and film. the less the amount of skin exposure', it was 40.6%. showing less knowledge for these two items. 2. The average attitude score for the defense of radiation was 64.24 (full score=75): By the demographic features, the attitude score was higher with respondents who were 31-35 years old. 11-15 years of working. and having radiation education. The attitude score by questionnaire items was generally high for all the items. 3. The average behavior score for the defense of radiation was 45.43: (a) By the demographic features, the behavior score for the defense of radiation was appeared to be higher with respondents who were dentists for occupational category, the aged for age, holding higher diploma for academic background, working in the university hospitals for workplace, and having longer occupational career for the year of working. (b) The behavior score for the defense of radiation by questionnaire items was lower than that of the attitude score for all the items. For the item, 'the amount of X-ray radiation is adjusted according to such conditions as patients' age, radiating areas, and kind of films', the score was 4.03; and for the item, 'Must receive the education of safety management of radiation periodically', the score was 1.73 and it was the lowest one. 4. As for the correlation among the knowledge, attitude, and behavior for the defense of radiation, the higher the level of knowledge and attitude, the higher the level of behavior.

• Korean Journal of Radiology
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• 제22권11호
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• pp.1786-1796
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• 2021

Objective: To evaluate the prognostic implications of preoperative magnetic resonance imaging (MRI) features of hepatocellular carcinoma (HCC) with a focus on those with targetoid appearance based on the Liver Imaging Reporting and Data System (LI-RADS), as well as known microvascular invasion (MVI) features. Materials and Methods: This retrospective study included 242 patients (190 male; mean age, 57.1 years) who underwent surgical resection of a single HCC (≤ 5 cm) as well as preoperative gadoxetic acid-enhanced MRI between January 2012 and March 2015. LI-RADS category was assigned, and the LR-M category was further classified into two groups according to rim arterial-phase hyperenhancement (APHE). The imaging features associated with MVI were also assessed. The overall survival (OS), recurrence-free survival (RFS), and their associated factors were evaluated. Results: Among the 242 HCCs, 190 (78.5%), 25 (10.3%), and 27 (11.2%) were classified as LR-4/5, LR-M with rim APHE, and LR-M without rim APHE, respectively. LR-M with rim APHE (vs. LR-4/5; hazard ratio [HR] for OS, 5.48 [p = 0.002]; HR for RFS, 2.09 [p = 0.042]) and tumor size (per cm increase; HR for OS, 6.04 [p = 0.009]; HR for RFS, 1.77 [p = 0.014]) but not MVI imaging features (p > 0.05) were independent factors associated with OS and RFS. Compared to the 5-year OS and RFS rates in the LR-4/5 group (93.9% and 66.8%, respectively), the LR-M with rim APHE group had significantly lower rates (68.0% and 45.8%, respectively, both p < 0.05), while the LR-M without rim APHE group did not significantly differ in the survival rates (91.3% and 80.2%, respectively, both p > 0.05). Conclusion: Further classification of LR-M according to the presence of rim APHE may help predict the postoperative prognosis of patients with a single HCC.

• Korean Journal of Radiology
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• 제22권10호
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• pp.1628-1639
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• 2021

Objective: Based on the Liver Imaging Reporting and Data System version 2018 (LI-RADS, v2018), this study aimed to analyze LR-5 diagnostic performance for hepatocellular carcinoma (HCC) when threshold growth as a major feature is replaced by a more HCC-specific ancillary feature, as well as the frequency of threshold growth in HCC and non-HCC malignancies and its association with tumor size. Materials and Methods: This retrospective study included treatment-naive patients who underwent gadoxetate disodium-enhanced MRIs for focal hepatic lesions and surgery between January 2009 and December 2016. The frequency of major and ancillary features was evaluated for HCC and non-HCC malignancies, and the LR-category was assessed. Ancillary features that were significantly more prevalent in HCC were then used to either replace threshold growth or were added as additional major features, and the diagnostic performance of the readjusted LR category was compared to the LI-RADS v2018. Results: A total of 1013 observations were analyzed. Unlike arterial phase hyperenhancement, washout, or enhancing capsule which were more prevalent in HCCs than in non-HCC malignancies (521/616 vs. 18/58, 489/616 vs. 19/58, and 181/616 vs. 5/58, respectively; p < 0.001), threshold growth was more prevalent in non-HCC malignancies than in HCCs (11/23 vs. 17/119; p < 0.001). The mean size of non-HCC malignancies showing threshold growth was significantly smaller than that of non-HCC malignancies without threshold growth (22.2 mm vs. 42.9 mm, p = 0.040). Similar results were found for HCCs; however, the difference was not significant (26.8 mm vs. 33.1 mm, p = 0.184). Additionally, Fat-in-nodule was more frequent in HCCs than in non-HCC malignancies (99/616 vs. 2/58, p = 0.010). When threshold growth and fat-in-nodule were considered as ancillary and major features, respectively, LR-5 sensitivity (73.2% vs. 73.9%, p = 0.289) and specificity (98.2% vs. 98.5%, p > 0.999) were comparable to the LI-RADS v2018. Conclusion: Threshold growth is not a significant diagnostic indicator of HCC and is more common in non-HCC malignancies. The diagnostic performance of LR-5 was comparable when threshold growth was recategorized as an ancillary feature and replaced by a more HCC-specific ancillary feature.

• 한국압력기기공학회 논문집
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• 제5권2호
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• pp.20-26
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• 2009

The dominant incidents category for onshore and offshore natural gas transmission pipelines in the world is associated with outside forces. Incidents in the outside forces category embrace acts of nature, which typically cause widespread structural damage, as well as act of man, whose effects tend to cause dents and/or gouges localized at point of contact that are referred to as mechanical damage. Therefore, these damage types must be better addressed to avoid unnecessary and costly repairs and the possibility of catastrophic events. First of all, the characterizing features of mechanical damage in gas pipelines were evaluated by using of excavator or boring machine. There is no reliable method for evaluating the safe operating pressure of pipeline affected by mechanical damage. It is especially important to evaluate the remaining strength of damaged pipelines due to outside force. Therefore, the full scale burst tests were conducted to evaluate the remaining strength of pipe with mechanical damage that combines a dent and a gouge. This paper is supposed to provide information that will assist in developing a criterion to assess serviceability in pipelines with mechanical damage.

• Journal of Communications and Networks
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• 제13권2호
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• pp.149-159
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• 2011

In this paper, we study the problem of how to design a medical-grade wireless local area network (WLAN) for healthcare facilities. First, unlike the IEEE 802.11e MAC, which categorizes traffic primarily by their delay constraints, we prioritize medical applications according to their medical urgency. Second, we propose a mechanism that can guarantee absolute priority to each traffic category, which is critical for medical-grade quality of service (QoS), while the conventional 802.11e MAC only provides relative priority to each traffic category. Based on absolute priority, we focus on the performance of real-time patient monitoring applications, and derive the optimal contention window size that can significantly improve the throughput performance. Finally, for proper performance evaluation from a medical viewpoint, we introduce the weighted diagnostic distortion (WDD) as a medical QoS metric to effectively measure the medical diagnosability by extracting the main diagnostic features of medical signal. Our simulation result shows that the proposed mechanism, together with medical categorization using absolute priority, can significantly improve the medical-grade QoS performance over the conventional IEEE 802.11e MAC.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권5호
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• pp.1413-1432
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• 2023

Recommender systems aim to recommend items to users by taking into account their probable interests. This study focuses on creating a model that utilizes multiple sources of information about users and items by employing a multimodality approach. The study addresses the task of how to gather information from different sources (modalities) and transform them into a uniform format, resulting in a multi-modal feature description for users and items. This work also aims to transform and represent the features extracted from different modalities so that the information is in a compatible format for integration and contains important, useful information for the prediction model. To achieve this goal, we propose a novel multi-modal recommendation model, which involves extracting latent features of users and items from a utility matrix using matrix factorization techniques. Various transformation techniques are utilized to extract features from other sources of information such as user reviews, item descriptions, and item categories. We also proposed the use of Principal Component Analysis (PCA) and Feature Selection techniques to reduce the data dimension and extract important features as well as remove noisy features to increase the accuracy of the model. We conducted several different experimental models based on different subsets of modalities on the MovieLens and Amazon sub-category datasets. According to the experimental results, the proposed model significantly enhances the accuracy of recommendations when compared to SVD, which is acknowledged as one of the most effective models for recommender systems. Specifically, the proposed model reduces the RMSE by a range of 4.8% to 21.43% and increases the Precision by a range of 2.07% to 26.49% for the Amazon datasets. Similarly, for the MovieLens dataset, the proposed model reduces the RMSE by 45.61% and increases the Precision by 14.06%. Additionally, the experimental results on both datasets demonstrate that combining information from multiple modalities in the proposed model leads to superior outcomes compared to relying on a single type of information.

• 한국시스템다이내믹스연구
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• 제16권2호
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• pp.75-100
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• 2015

The purpose of this study is to analyze causation of Ecosystem service's trade-off(ES trade-off) and to establish baseline data for wise spatial planning and management. In order to understand why and how ES trade-off occurs, systems thinking and causal loops were employed. The causal loop of ecosystem service creation cycle includes profits quantification process, decision making process, spatial planning and management process, and ecosystem services creation process. The profits quantification process has a limitation that all ecosystem service categories were not included in profits quantification, because quantification method for cultural services is insufficient. These problems led to unequal discussion opportunity in decision making process. ES trade-off occurs through transition of ecosystem function in spatial scale and temporal scale. In spatial scale, land-use variation and resource-use variation contribute to change an ecosystem function for different ES category by spatial planning and management. In temporal scale, a change of an ecosystem function for different ES category is influenced by ecological succession, seasonal change and land cover variation, which are parameter from environmental features. This study presented that spatial planning and management should ecosystem service assessment in order to enhance balanced ecosystem services.

• Tuberculosis and Respiratory Diseases
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• 제46권5호
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• pp.718-722
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• 1999

14세 여자 환자에서 무증상의 전종격동 낭성 종괴가 있어 절제적 생검을 시행하여 고분화성 흉선암종의 광범위한 낭성 변화로 확진되어 제1기의 흉선종을 완전 적출 후 방사선 치료 혹은 병합화학요법 없이 추후 흉부전산화단층촬영 예정으로 외래에서 경과 관찰 중인 1예를 경험하여 문헌 고찰과 함께 보고하는 바이다.

• 대한두경부종양학회지
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• 제40권1호
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• pp.1-5
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• 2024

The Bethesda System for Reporting Thyroid Cytopathology (TBSRCT) is crucial for cytopathologists to use a standardized, category-based reporting system for thyroid fine needle aspirations and is effective for clear communication with the referring physicians. The new Bethesda System for Reporting Thyroid Cytopathology, the third edition in 2023, provides several key updates. The most important update is the assignment of only single name for each of the six diagnostic categories: (I) nondiagnostic; (II) benign; (III) atypia of undetermined significance; (IV) follicular neoplasm; (V) suspicious for malignancy; and (VI) malignant. An implied risk of malignancy (ROM) for each of six categories has been updated based on extensively published data since the second edition of TBSRTC in 2017 and offers both an average ROM for each category and the expected range of cancer risk. Estimated final ROM after excluding "Noninvasive Follicular Thyroid Neoplasm with Papillary Like Nuclear Features (NIFTP)" for each of six categories has been updated based on the reported mean decreases in the ROM if excluding NIFTP. For atypia of undetermined significance (AUS) category, the subcategorization is simplified and more formalized into 2 subgroups, AUS-nuclear atypia or AUS-other, based on the implied ROM and molecular profiling. For the pediatric thyroid disease, pediatric ROMs and management algorithms are newly added for the same six reporting categories for this age group. New or revised disease nomenclatures including high-grade follicular-derived carcinoma has been updated according to the recently published 2022 World Health Organization Classification of Thyroid Neoplasms. Brand new two chapters are added including clinical perspectives and imaging studies (Chap. 13) and the use of molecular and other ancillary tests (Chap. 14). The atlas is updated with new images to illustrate more effectively for new disease entity and diagnostic criteria.