• Korean Journal of Radiology
• /
• v.22 no.10
• /
• pp.1697-1707
• /
• 2021

The recent introduction of various high-dimensional modeling methods, such as radiomics and deep learning, has created a much greater diversity in modeling approaches for survival prediction (or, more generally, time-to-event prediction). The newness of the recent modeling approaches and unfamiliarity with the model outputs may confuse some researchers and practitioners about the evaluation of the performance of such models. Methodological literacy to critically appraise the performance evaluation of the models and, ideally, the ability to conduct such an evaluation would be needed for those who want to develop models or apply them in practice. This article intends to provide intuitive, conceptual, and practical explanations of the statistical methods for evaluating the performance of survival prediction models with minimal usage of mathematical descriptions. It covers from conventional to deep learning methods, and emphasis has been placed on recent modeling approaches. This review article includes straightforward explanations of C indices (Harrell's C index, etc.), time-dependent receiver operating characteristic curve analysis, calibration plot, other methods for evaluating the calibration performance, and Brier score.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.23 no.56
• /
• pp.65-85
• /
• 2000

Industrial accidents have been consistently increased in terms of medical costs, lost work days, and incidence rates every year in Korea. Since the infrastructure of the industry changed shifts rapidly from 1980s in the developing countries such as South Korea, the nature and magnitude of the industrial accidents have also undergone a major shift. The situation is especially severe in small-to-medium sized industry(SMI). This article reports the development of a systematic evaluation system of risk factors specifically for the SMIs. The new approach introduced by this article is geared to the systematic identification and evaluation of the injuries from power press machines using the Analytic Hierarchy Process with the key evaluation data generated and evaluated by the employees on site. A total of 21 companies was studied and surveyed using the hierarchical structures of the cause-effect relationship of the mechanical injuries and their countermeasures. For the relative weighting of each risk factor, separate questionnaire survey was conducted for the selected workers from each company who had worked for more than 10 years in press work. Most participants (48 out of 62) replied that human attributes were the most significant factors for mechanical injuries fellowed by administration, machine, and work environment factors. The result also showed that the self-motivated risk assessment and safety enhancement activities would be an effective and efficient way of managing the risk factors in the SMIs.

• Geomechanics and Engineering
• /
• v.22 no.1
• /
• pp.25-33
• /
• 2020

In metropolitan areas, the quantity and density of the underground structure increase rapidly in recent years. Even though most damage incidents of the underground structure were minor, there were still few incidents causing a great loss in lives and economy. Therefore, the safety evaluation of the underground structure becomes an important issue in the disaster prevention plan. Liquefaction induced uplift is one important factor damaging the underground structure. In order to perform a preliminary evaluation on the safety of the underground structure, simplified prediction equations were introduced to provide a first order estimation of the liquefaction induced uplift. From previous studies, the input motion is a major factor affecting the magnitude of the uplift. However, effects of the input motion were not studied and included in these equations in an appropriate and rational manner. In this article, a numerical simulation approach (FLAC program with UBCSAND model) is adopted to study effects of the input motion on the uplift. Numerical results show that the uplift and the Arias Intensity (Ia) are closely related. A simple modification procedure to include the input motion effects in the Sasaki and Tamura prediction equation is proposed in this article for engineering practices.

• Proceedings of the KIEE Conference
• /
• 2006.10c
• /
• pp.394-396
• /
• 2006

When developing a new GPS receiver module, the essential problems are evaluation of reliable algorithms, software debugging, and performance comparison between algorithms to find optimal solution. Most GPS receiver modules nowadays use a correlator to track signals from satellites and an MCU (Micro Controller Unit) to control operations of the entire module. The problem of software evaluation from MCU is very difficult, due to limitation of MCU resources and low ability of interfacing with user. Normally, user has to expense special tool kit for a limiting access to MCU but it is also hard to use. This article introduces an implementation of a GPS receiver test bed using correlator GP2021 interfacing with ISA (Industry Standard Architecture) PC bus. This way can give user complete control and visibility into the operation of the receiver, then user can easily debug program and test algorithms. For this article, the least square method is implemented to test the hardware and software performance.

• Journal of Information Science Theory and Practice
• /
• v.3 no.4
• /
• pp.19-34
• /
• 2015

Evaluation of retrieval systems is mostly limited to laboratory settings and rarely considers changes of performance over time. This article presents an evaluation of retrieval systems for internal Web site search systems between the years 2006 and 2011. A holistic evaluation methodology for real Web sites was developed which includes tests for functionality, search quality, and user interaction. Among other sites, one set of 20 Web site search systems was evaluated three times in different years and no substantial improvement could be shown. It is surprising that the communication between site and user still leads to very poor results in many cases. Overall, the quality of these search systems could be improved, and several areas for improvement are apparent from our evaluation. For a comparison, Google’s site search function was also tested with the same tasks.

• Physical Therapy Korea
• /
• v.2 no.2
• /
• pp.98-107
• /
• 1995

Physical therapists use assumptions about motor control in every aspect of their work in treating stroke patients. An understanding of the recovery process after stroke, some neural mechanism of recovery and therapeutic model is critical factor for physical therapist to evaluate and obtain a higher final stage of recovery. The purpose of this article was to review the recovery process after stroke, some neural mechanism of recovery, the role of rehabilitation in the process of recovery, therapeutic model and its limitation. This article will help understanding of recovery process. evaluation, and treatment of the stroke patients. Each therapeutic method consists of a different set of assumptions and they are not completely independent of one another. Therefore specializing in any techniques of physical therapy will not be enough to treat stroke, so we are in need of integrated approach and objective measurement instrument to adequately evaluate and treat stroke patients.

• Journal of Arbitration Studies
• /
• v.23 no.1
• /
• pp.133-152
• /
• 2013

Recently, the United Nations Commission on International Trade Law (UNCITRAL) has made progress toward resolving low value, high volume disputes in international e-commerce. At the Working Group's 26th session, two draft procedural rules were addressed. The first discussed the draft of Article 9, entitled "Decision by a neutral party." This is based on the suggestion in 26th session to have a "two track" system of ODR, one including negotiation, facilitated settlement, and arbitration phrases, and the other not including an arbitration phase. The second draft procedural rule, draft Article 10, regards the language of proceedings. In most cases of international e-commerce, the decision of language of an ODR proceeding is a matter of importance, for the language parties could differ from each other. This paper examines several implications of UNCITRAL for Korea, which has unstable ODR system.

• The Journal of Korean Physical Therapy
• /
• v.14 no.1
• /
• pp.177-186
• /
• 2002

The purpose of this study was to contribute to the development of clinical instruction by students ratings of teaching effectiveness in clinical education. The instrument used in this study was teaching effectiveness of clinical nursing by Yu and modified evaluation method by Kern and Mickelson. The results were are follows 1. Among the 12 categorial components of clinical teaching effectiveness, the highest satisfaction was 'encouraging to think for themselves' and the lowest was 'attitude of teacher and evaluation' 2. To compare teaching effectiveness between sex, 'resource for student' and 'professional competence' showed statistical significance. 3. To compare teaching effectiveness among clinical practice stage, 'encouraging' 'role model', 'professional competence', 'organization of subject mater' and 'attitude of teacher and evaluation' showed statistical significance. 5. Interrater ICCs for evaluation method did not showed statistical significance and interitem ICCs showed statistical significance. This article presents goal of clinical education, development of clinical instructor's educational program and a standardized method to measure clinical performance.

• Proceedings of the Korean Information Science Society Conference
• /
• 2006.10b
• /
• pp.233-237
• /
• 2006

This study proposes an innovative measure for evaluating the performance of text clustering. In using K-means algorithm and Kohonen Networks for text clustering, the number clusters is fixed initially by configuring it as their parameter, while in using single pass algorithm for text clustering, the number of clusters is not predictable. Using labeled documents, the result of text clustering using K-means algorithm or Kohonen Network is able to be evaluated by setting the number of clusters as the number of the given target categories, mapping each cluster to a target category, and using the evaluation measures of text. But in using single pass algorithm, if the number of clusters is different from the number of target categories, such measures are useless for evaluating the result of text clustering. This study proposes an evaluation measure of text clustering based on intra-cluster similarity and inter-cluster similarity, what is called CI (Clustering Index) in this article.

• Computers and Concrete
• /
• v.9 no.4
• /
• pp.275-291
• /
• 2012

The service loads are often decisive in the design of concrete structures. The evaluation of the cracking moment, $M_{cr}$, is an important issue to predict the performance of the structure, such as, the deflections of the reinforced concrete beams and slabs. To neglect the steel bars of the section is a simplification that is normally used in the computation of the cracking moment. Such simplification leads to small errors in the value of this moment (typically less than 20%). However, these small errors can conduce to significant errors when the values of deflections need to be computed from $M_{cr}$. The article shows that an error of 10% on the evaluation of $M_{cr}$ can lead to errors over 100% in the deformation values. When the deformation of the structure is the decisive design parameter, the exact computing of the cracking moment is obviously very important. Such rigorous computing might lead to important savings in the cost of the structure. With this article the authors wish to draw the attention of the technical community to this fact. A simple equation to evaluate the cracking moment, $M_{cr}$, is proposed for a rectangular cross-section. This equation leads to cracking moments higher than those obtained by neglecting the reinforcement bars and is a simple rule that can be included in Eurocode 2. To verify the accuracy of the developed model, the results of the proposed equation was compared with a rigorous computational procedure. The proposed equation corresponds to a good agreement when compared with the previous approach and, therefore, this model can be used as a practical aid for calculating an accurate value of the cracking moment.