• The Korean Journal of Applied Statistics
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• v.35 no.1
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• pp.35-47
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• 2022

The receiver operating characteristic (ROC) curve was developed to quantify the classification ability of marker values (covariates) on the response variable and has been extended to survival data with diverse missing data structure. When survival data is understood as binary data (status of being alive or dead) at each time point, the ROC curve expressed at every time point results in time-dependent ROC curve and time-dependent area under curve (AUC). In particular, a follow-up study brings the change of cohort and incomplete data structures such as censoring and competing risk. In this paper, we review time-dependent ROC estimators under several contexts and perform simulation to check the performance of each estimators. We analyzed a dementia dataset to compare the prognostic power of markers.

• Asian Oncology Nursing
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• v.12 no.3
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• pp.237-245
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• 2012

Purpose: The purpose of this study was to identify attributes of the concept of cancer survivorship. Methods: Walker & Avant's concept analysis framework (2005) was used to review the medical & nursing text books, medical and nursing research articles related to cancer survivorship and published from 1985 to 2011. Results: There were nine aspects of the concept of cancer survivorship: A process, liminality, uncertainty, life-changing experience, complexity, unique experience, duality of positive and negative aspects, partnership, and need for support. Antecedents of cancer survivorship were cancer diagnosis and perception as a cancer survivor. Empirical referents of cancer survivorship were survival rate, quality of life, adaptation to the survivorship experience, and health-related hardiness, social support, spirituality, and health behavior. The consequences of cancer survivorship were effects on the physical, psychosocial, spiritual and socio-economic well-being of the patients. Conclusion: This concept analysis of cancer survivorship is expected to contribute to promotion of survivorship care in the clinical field by removing conceptual ambiguity and confirming the true meaning of survivorship care.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.105-114
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• 2017

The purpose of this study was to examine the effects of obesity at diagnosis on the prognosis of Korean breast cancer patients after classifying them according to their reproductive history and age by comparing the overall survival rate (OS) and disease-free survival rate (DFS). This study is a retrospective cohort study using 4181 breast cancer cases at one of the medical centers in Korea during the 3 year period from 2006 to 2008. We confirmed the levels of death and recurrence through a follow-up study completed in May 30. 2015. In conclusion, the parous patients had a lower OS than the non-parous patients (p=.000), and the younger patients below 40 years old had a lower OS and DFS than those who were 40 years old or older (p=.003, p=.000), while obesity did not affect the OS and DFS significantly. However, several subgroups in which obesity affected the OS and DFS were found after classifying the patients according to their reproductive history and age. For the subgroups classified by reproductive history, the obese patients had a lower OS and DFS than the non-obese patients in the subgroup in which the patients have a reproductive history (p=.001, p=.005). For the subgroups classified according to age, the obese patients had a lower OS and DFS than the non-obese patients in the subgroup in which the patients were 40 years old or older (p=.005, p=.014). Obesity affected the OS and DFS in the subgroup in which the patients were 40 years old or older and had a reproductive history (p=.000, p=.003). The results of this study show that obesity has an effect on the prognosis of breast cancer patients in the subgroups classified by reproductive history and age, whereas it has no effect on the OS and DFS of the patients when they are examined in their entirety. It also suggests that appropriate nursing intervention is needed for the subgroups in which obesity has effects on prognosis.

• The Korean Journal of Applied Statistics
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• v.11 no.1
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• pp.113-127
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• 1998

There have been a great deal of interests in comparing two survival distributins in clinical trials. This paper compares some well-known statistical methods for testing the equality of two survival distributions. Simulation studies also provide some insights into the properties of these test statistics across several types of survival distributions and degrees of censorship.

• Journal of the Korea Society of Computer and Information
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• v.29 no.1
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• pp.131-138
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• 2024

The ability of Combat Management System(CMS) to respond quickly and accurately to threat to a naval vessel is directly related to the survivability and combat power of the vessel. However, current method for detecting enemy submarine periscope in CMS rely on manual and subjective method that require operators to manually verify and analyze information received from sensor. This delays the response time to the threat, making the vessel less viable. This paper introduces a periscope detection algorithm that classifies the plot information generated by High Resolution Range Profile(HRRP) into probability-based suspicion classes and dramatically reduces threat response time through classified notifications. Algorithm validation showed 133.3791 × 10⁶ times faster and 12.78%p higher detection rate than operator, confirming the potential for reduces threat response time to increase vessel survivability.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.619-623
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• 2008

Recently, the restriction of contracting business between general and specialty contractors are deregulated, which means the elimination of the traditional market entry block in the Korean construction industry. It could be a threat and/or an opportunity to construction firms, and requires establishing new business strategies in order to obtain relative competitiveness between the general and the specialty. Under this change in the industry, this research performed to provide some suggestions for specialty firms in setting up their new business strategies by analyzing various changes of their competitiveness elements. This study extracted 20 core competitiveness elements from major 6 competitive categories required in doing specialty contracting business, and their relative importance between the 20 elements were measured. It was found that the specialty's relative competitiveness has been greatly changed and affected by the deregulation of the protective business restriction.

• The Korean Journal of Financial Studies
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• v.10 no.1
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• pp.45-72
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• 2004

본 연구에서는 우리나라에서 EVA의 주가변동에 대한 설명력을 실증적으로 분석함으로써 주주가치 극대화의 규범이 어느 정도로 통용되고 있는가를 고찰하였다. 이와 같이 EVA의 주가변동에 대한 설명력을 분석해봄으로써 자본자유화 이후 상대적으로 주주가치 극대화의 규범이 한국자본주의에 어느 정도 영향을 주었는지 판단할 수 있다. 실증분석의 결과를 종합해볼 때, 우리나라에서는 EVA의 주가변동에 대한 설명력이 그다지 뚜렷하지 않은 것으로 판단된다. 보다 확고한 판단을 내리기 위하여 당기 순이익과 매출액을 사용한 모형들과 서로 비교해보기도 하였지만 결과는 대동소이 하였다. 그리고 IMF 위기를 전후하여 시장에 구조적인 변화가 있었을 것이라는 전제 아래 표본기간을 위기가 발생한 시점을 기준으로 전과 후 두 기간을 구분하여 분석하기도 하였고, 산업별로 구분하여 고찰하기도 하였지만 결과는 기본적으로 동일하였다. 분석결과가 시사하는 바에 따르면 우리나라에는 아직 주주자본주의가 제대로 자리를 잡았다고 말할 수 없다. 그러나 기업들이 가치중심경영으로 패러다임을 신속하게 전환하지 못한다면 무한경쟁으로 집약되는 생존경쟁에서 결코 살아남지 못하기 때문에 기업들은 경영에 있어서 EVA를 더욱 중시하는 방향으로 전개할 것이다. 따라서 앞으로 EVA는 그 설명력을 점차 높여갈 것으로 판단된다.

• Environmental Analysis Health and Toxicology
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• v.20 no.1
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• pp.23-28
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• 2005

PAH 위해성 평가의 생체지표 개발을 위하여, benzo[a]pyrene을 인체 간암 세포주인 HepG2세포에 처리하여 암 억제 단백질인 p53 및 관련 단백질의 발현 양상에 대하여 연구하였다. HepG2 세포의 생존력은 benzo[a]pyrene을 노출시킨 군에서 농도가 증가할수록 감소하였다. p53과 인산화 p53의 발현 양상은 benzo[a]pyrene 농도 의존적으로 증가하는 경향을 보였으며, 반면에 아세틸화 p53은 benzo[a]pyrene의 농도가 증가할수록 감소하는 경향을 나타내었다. 세포 주기 조절에 관련된 p21 단백질은 화학 물질 처리에 의해서 p53과 마찬가지로 증가하였으나, CdK4와 Rb 단백질의 발현에는 변화가 없었다. 상관분석 결과 Benzo[a]pyrene 노출, 세포 생존력, p53, 인산화 p53, p21이 서로 높은 상관성을 보였다. 본 연구의 결과는 p53 단백질의 축적이 benzo[a]pyrene 독성에 있어 매우 중요한 현상이며, 이는 선택적인 지표와 함께 p53 이 benzo[a]pyrene과 같은 PAH 계열의 물질의 위해성 평가를 위한 민감한 생체 지표로써 개발될 수 있음을 시사한다.

• Korean Journal of Poultry Science
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• v.50 no.4
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• pp.303-310
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• 2023

The current study was conducted to compare the effect of crossbred on the body weight and laying performance of Korean native chicken from hatch to week 40. A total of 873 one-day-old chicks were divided into twelve crossbreds (i.e., CFCK, CFYC, CFYD, CKCF, CKYC, CKYD, YCYD, YCCF, YCCK, YDCF, YDCK, and YDYC) and commercial layer (Hy-Line Brown) were obtained as a counterpart in the study. All the birds are raised in battery cages (76 × 61 × 46 cm³) and then raised until 14 weeks and subsequently moved to layer battery cages (60 × 25 × 45 cm³) and raised until 16 weeks. The body weight and viability were measured biweekly from hatching to week 16. The week of 16, body weight range was about 1,010.24 to 1,411.77 g. The body weight of specific crossbreeds (i.e., CKCF, YCYD, and YDYC) was found to be comparable to that of Hy-Line Brown). The viability hatch to week 14 range was about 55 to 100% and however week 14 to 16 range was 80 to 100%. The crossbred (i.e., CKCF) recorded superior (P<0.05) viability throughout the whole experiment period, even compared with Hy-Line Brown (100% vs 96%). Our results are indicating that crossbreds Korean native chicken including CKCF, and YDYC has the potential to enhance key features of laying hens during the growing phase like optimal body weight and higher viability.

• Journal of Gastric Cancer
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• v.5 no.3 s.19
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• pp.174-179
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• 2005

Purpose: The 5-year survival rate is the most useful parameter for evaluating the effect of management on most malignant tumors. Recurrence after a curative resection for gastric cancer occurs mostly within 3 years of the operation, which caused us to evaluate whether a 3-year disease-free survival (3DFS) can be substituted for a 5-year overall survival (5OS). Materials and Methods: We reviewed the medical records of 656 consecutive patients who had undergone a curative resection for gastric cancer To assess whether 3DFS represents 5OS, we used a simple linear regression with survival probability calculated by using the survival function. Results: Recurrence was found in 175 cases during the follow-up periods. The accumulative frequencies of recurrence at postoperative 1 year, 3 years, and 5 years were 46% (81 cases), 89% (156 cases), and 97% (170 cases), respectively. The correlation coefficient (r) and the coefficient of determination $(r^2)$ between 3DFS and 5OS were 0.87 and 0.76, respectively, and the regression equation was $5OS=0.18+(0.80{\times}3DFS)$. The r and $R^2$ according to the type of recurrence were 0.89 and 0.80 in peritoneal seeding, 0.88 and 0.78 in hematogeneous metastasis, and 0.86 and 0.73 in local recurrence, respectively. The r (0.77) and $r^2$ (0.60) were relatively lower in low stages (stage I and II) compared to r (0.88) and $r^2(0.77)$ in high stages (stage III and IV). Conclusion: The 3DFS is an excellent predictor of 5OS. Therefore, if we use the former as the treatment evaluating method, 2-year time reduction in assessing and reporting treatment results is expected.