• The Korean Journal of Applied Statistics
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• v.37 no.4
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• pp.525-539
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• 2024

Massive multiplayer online role playing game (MMORPG) is a common type of game these days. Predicting user churn in MMORPG is a crucial task. The retention rate of users is deeply associated with the lifespan and revenue of the service. If the churn of a specific user can be predicted in advance, targeted promotions can be used to encourage their stay. Therefore, not only the accuracy of churn prediction but also the speed at which signs of churn can be detected is important. In this paper, we propose methods to identify early signs of churn by utilizing the daily predicted user retention probabilities. We train various deep learning and machine learning models using log data and estimate user retention probabilities. By analyzing the change patterns in these probabilities, we provide empirical rules for early identification of users at high risk of churn. Performance evaluations confirm that our methodology is more effective at detecting high risk users than existing methods based on login days. Finally, we suggest novel methods for customized marketing strategies. For this purpose, we provide guidelines of the percentage of accessed users who are at risk of churn.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.7
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• pp.3051-3056
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• 2015

Background: Skin self-examination (SSE) may facilitate early diagnosis of melanoma at a potentially curable stage. Little data are available concerning the SSE frequency and knowledge about the symptoms of melanoma in non-patient populations. The aim of our study was to assess the performance of skin self-examination, recognition of potential melanoma symptoms as well as behavior related to sun exposure among web users in Poland. Materials and Methods: A cross-sectional study was conducted among readers of a scientific portal. Invited respondents were asked to complete an online questionnaire. Finally, statistical analysis was conducted on 4,919 surveys towards potential clinical signs of melanoma and SSE performance. Results: Approximately 60% of respondents had ever performed SSE in their life. Only 18.4 % declared performance on a regular, monthly, basis. Factors promoting this activity were established to be bigger place of residence, higher education and sensitive skin phototype, higher level of knowledge concerning melanoma, safe tanning rules and, especially, past surgical excision of naevi. Declared longer use of tanning beds was linked to understanding better the importance of clinical features of melanoma. Awareness of hazardous behavior during sunbathing is associated with the attempts to change them. Conclusions: Regular SSE is not a common practice, whilst the knowledge about the clinical features of melanoma is varied. Therefore, constant pressure should be put on promotion of regular skin self-examination and teaching its proper techniques, including familiarity with the ABCD (asymmetry; border; color; diameter) rule and its extension of "EFG" (elevated, firm, progressive growth) criteria.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.2
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• pp.685-689
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• 2016

Opisthorchiasis is still a major health problem in rural communities of Thailand. Infection is associated with cholangiocarcinoma (CCA), which is found frequently in Thailand, particularly in the northeastern. Therefore, this study aimed to evaluate the effectiveness of health intervention in the population at risk for opisthorchiasis and CCA. A quasi-experimental study was conducted in Meuang Yang district, Nakhon Ratchasima province, northeastern Thailand, between June and October 2015. Participants were completed health intervention comprising 4 stations; 1, VDO clip of moving adult worm of liver fluke; 2, poster of life cycle of liver fluke; 3, microscopy with adult and egg liver fluke; and 4, brochure with the knowledge of liver fluke containing infection, signs, symptoms, related disease, diagnosis, treatment, prevention, and control. Pre-and-post-test questionnaires were utilized to collect data from all participants. Students paired t-tests were used to analyze differences between before and after participation in the health intervention. Knowledge (mean difference=-7.48, t=-51.241, 95% CI, -7.77, -7.19, p-value =0.001), attitude (mean difference=-9.07, t=-9.818, 95% CI=-10.9, -7.24, p-value=0.001), and practice (mean difference=-2.04, t=-2.688, 95% CI=-3.55, -0.53, p-value=0.008), changed between before and after time points with statistical significance. Community rules were concluded regarding: (1) cooked cyprinoid fish consumption; (2) stop under cooked cyprinoid fish by household cooker; (3) cooked food consumption; (4) hygienic defecation; (5) corrected knowledge campaign close to each household; (6) organizing a village food safety club; (7) and annual health check including stool examination featuring monitoring by village health volunteers and local public health officers. The results indicates that the present health intervention program was effective and easy to understand, with low cost and taking only a short time. Therefore, this program may useful for further work at community and provincial levels for liver fluke prevention and control.

• Journal of the Korean Institute of Oriental Medical Informatics
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• v.14 no.1
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• pp.55-61
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• 2008

The Taekwondo is the martial arts where possibility thousand Ul of history and the ancestor is put in with specific martial arts of our nation. Also it practiced with the self defense martial arts which rules over the body and a mind and it came, the country from crisis of imminent danger won a victory with the good state affair alcoholic beverage and it was come. The ancestors condition anger the Taekwondo where the soul is put in were born again with martial arts of the world and they became and the world-wide conference was adopted with the Olympic formal item which becomes the historian of of course sports and became the martial arts in the world-wide center. In like this features martial arts even from each country condition anger and the sports raises the phase of the country is racing with of course martial arts. Specially from China it makes the right shoe which is a Chinese martial arts with condition item and sports anger the features of the martial arts origination to do and there is a possibility of seeing the features which in the succession nose sleeping martial arts perforation defends it concentrates. The martial arts perforation character is letting in religion and philosophy thought of the Orient. Confucianism and Buddhism, it puts in the teaching of friendship thoughts and heaven and earth positive and negative principles, five lines and eight divination signs. Features of like this perforation our ancestors the positive and negative principles where the philosophy of the Orient is put in, there is a possibility of searching from life and the Taekwondo which it does with at five events together. With history of the ancestor it breathes together and all Taekwondo operation every one by one it puts in the thought of our ancestors as well. The some branch it tried to listen to the representative example which the feather holds hereupon in basic operation, the Taoist garment, the belt and width tax of Taekwondo. The flesh which is healthy in the spirit which is healthy holds the feather. Taekwondo Oh! as the true feelings one martial art which accomplishes the artificial flower of the dynamic thing and the static thing at end with the perforation essentially it is deep it will be able to confirm repeatedly fire tube characteristic.

• The Journal of Korean Medical History
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• v.23 no.2
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• pp.23-36
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• 2010

In this paper, this writer looked into the initial law and fortification, which are two of the most important phonetic changes of Sino-Korean words. Pronunciation and inscription rules of Oriental Medical terminologies have also been studied. Moreover, several problems of meaningful rendering of Oriental Medical Chinese terminologies into Korean have been looked into. As a result, the following conclusions could be drawn. 1. The initial law only applies to Sino-Korean words that consist of more than one syllable. It does not apply to words borrowed from foreign languages. Especially, compound words like Jang-ssi-yu-gyeong(張氏類經) or Im-sin-yuk-hyeol(姙娠衄血) consist of already existing words such as Jang-ssi(張氏), Yu-gyeong(類經), Im-sin(姙娠), and Yuk-hyeol(衄血), and thus the initial law applies to these words. They are inscribed and pronounced 'Jang-ssi-yu-gyeong' and 'Im-sin-yuk-hyeol'. 2. Fortification of Sino-Korean words can be applied variously according to the structure and meaning of the words. Words such as '科', '格', '氣', '法', '病', '症', and '證' are often fortified and at the same time used frequently in Oriental Medicine. Also, many other words are derived from these words. However, there has not been a scholastic consent among the Oriental Medical society as to in which circumstances these words will be fortified. Therefore, a standardization process to stipulate the pronunciation of Oriental Medical terminologies is necessary. 3. Meaningful rendering of Oriental Medical Chinese terminologies into Korean also needs scholastic investigation. Especially, the word 兪 should be meaningfully rendered and pronounced 'su' just like the words 輸 and 腧, but is wrongly pronounced 'yu'. Other than this, the words 井滎兪經合, 秦艽, 膻中, 共振丹, 成無已, and 麗澤通氣湯 should respectively be pronounced 'jeong-hyeong-su-gyeong-hap', 'jin-gyo', 'dan-jung', 'gong-sin-dan', 'Seong-mu-yi', and 'Yi-taek-tong-gi-tang'. Moreover, there are four pronunciations to the word 梴 of 李梴. This should also be standardized. This writer proposes that in the future, correct meaningful rendering of Chinese terminologies into Korean and phonetic signs be inscribed in dictionaries regarding Oriental Medical terminologies.

• Journal of the Ergonomics Society of Korea
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• v.32 no.1
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• pp.117-124
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• 2013

Objective: This paper presents additional considerations related to organization and safety culture extracted from recent human error incidents in Korea, such as station blackout(i.e., SBO) in Kori#1. Background: Safety culture has been already highlighted as a major cause of human errors after 1986 Chernobyl accident. After Fukushima accident in Japan, the public acceptance for nuclear energy has taken its toll. Organizational characteristics and culture became elucidated as a major contributor again. Therefore many nuclear countries are re-evaluating their safety culture, and discussing any preparedness and its improvement. On top of that, there was an SBO in 2012 in the Kori#1. Korean public feels frustrated due to the similar human errors causing to a catastrophe like Fukushima accident. Method: This paper reassesses Japan's incidents, and revisits Korea's recent incidents. It focuses on the analysis of the hazards rather than the causes of human errors, the derivation of countermeasures, and their implementation. The preceding incidents and conclusions from Japanese experience are also re-analyzed. The Fukushima accident was an SBO due to the natural disaster such as earthquakes and a successive tsunami. Unlike the Fukushima accident, the Kori#1 incident itself was simple and restored without any loss and radioactive release. However, the fact that the incident was deliberately concealed led to massive distrust. Moreover, the continued violation of rules and organized concealment of the accident are serious signs of a new distorted type of human errors, blatantly revealing the cultural and fundamental weakness of the current organization. Result: We should learn from Japanese experiences who had taken pride in its safety technology and fairly high confidence in safety culture. Japan's first criticality accident in JCO facility splashed cold water on that confidence. It has turned out to be a typical case revealing the problems in the organization and safety culture. Since Japan has failed to gain lessons and countermeasure, the issue persists to the Fukushima incident. Conclusion: Safety culture is not a specific independent element, which makes it difficult to either evaluate it properly or establish countermeasures from the lessons. It may continue to expose similar human errors such as concealment of incident and manipulation of bad data. Application: Not only will this work establish the course of research for organization and safety culture, but this work will also contribute to the revitalization of Korea's nuclear industry from the disappointment after the export contract to UAE.

• 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.