• 한국간호교육학회지
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• 제8권1호
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• pp.51-60
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• 2002

The purpose of this study was to identify the relationship between self-esteem, self- efficacy and clinical practice performance, academic achievement, decision making of major field in clinical practice . The study subjects consisted with 244 students from G. junior nursing college that will adapt a new majoring program of clinical nursing practice funded by Ministry of human and resources development. Data were analyzed using descriptive statistics, and t-test, Pearson correlation, and multiple regression. The results of this study were summarized as follows: 1. The students were relatively performed well in clinical practice setting (total M :3.78). The item of student's personal relationship between patients, patient's family, and professional staff showed high score (M=3.96). However students did not feel comfortable to communicate with patients, patient's family and professional staffs in clinical setting(mean=3.56). 2. Students who had experiences of temporal absence from school showed significant difference in the variable of academic achievement and decision making of major field in clinical practice Students who entered to nursing school with self-motive revealed statistically significant difference in the variable of clinical practice performance, academic achievement, self-esteem, self-efficacy, and decision making of major field in clinical practice. 3. There was a significant correlation between self-esteem and clinical practice performance, (r=.512, p<.000). And the relation between self-esteem and decision making of major field in clinical practice was significantly correlated(r=.377, p<.000). Self-efficacy and clinical practice performance(r=.567, p<.000), and decision making of major field in clinical practice (r=.441, p<.000) showed significant correlations. Also relation between academic achievement and self-esteem reveled a significant correlation(r=.129, p<.05) but correlation between self-efficacy and academic achievement was not significant. 4. Correlation between clinical practice performance and decision making of major field in clinical practice also identified a significant relation(r=.498, p<.000). 5. Self-esteem and self-efficacy variables predicted clinical practice performance and explained 37.7% of clinical practice performance. 6. Aptitude and personal interests(m=4.07) reveled important factor affecting to select majoring area in clinical practice, and advice from parents reflected low percentage on selecting places(m=2.42). In conclusion, the variables of self-esteem and self-efficacy showed significant correlations with the variables of student's clinical practice performance, academic achievement, and decision making of major field in clinical practice. Thus it is recommended that student's affective domain of self-esteem and self-efficacy should be developed by nursing intervention before clinical nursing education.

• 대한수학회논문집
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• 제32권1호
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• pp.7-17
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• 2017

Let R be a commutative ring with zero-divisors Z(R). The extended zero-divisor graph of R, denoted by $\bar{\Gamma}(R)$, is the (simple) graph with vertices $Z(R)^*=Z(R){\backslash}\{0\}$, the set of nonzero zero-divisors of R, where two distinct nonzero zero-divisors x and y are adjacent whenever there exist two non-negative integers n and m such that $x^ny^m=0$ with $x^n{\neq}0$ and $y^m{\neq}0$. In this paper, we consider the extended zero-divisor graphs of idealizations $R{\ltimes}M$ (where M is an R-module). At first, we distinguish when $\bar{\Gamma}(R{\ltimes}M)$ and the classical zero-divisor graph ${\Gamma}(R{\ltimes}M)$ coincide. Various examples in this context are given. Among other things, the diameter and the girth of $\bar{\Gamma}(R{\ltimes}M)$ are also studied.

• 대한방사선기술학회지:방사선기술과학
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• 제46권2호
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• pp.131-139
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• 2023

High-dose I-131 used for the treatment of thyroid cancer causes localized exposure among radiology technologists handling it. There is a delay between the calibration date and when the dose of I-131 is administered to a patient. Therefore, it is necessary to directly measure the radioactivity of the administered dose using a dose calibrator. In this study, we attempted to apply machine learning modeling to measured external dose rates from shielded I-131 in order to predict their radioactivity. External dose rates were measured at 1 m, 0.3 m, and 0.1 m distances from a shielded container with the I-131, with a total of 868 sets of measurements taken. For the modeling process, we utilized the hold-out method to partition the data with a 7:3 ratio (609 for the training set:259 for the test set). For the machine learning algorithms, we chose linear regression, decision tree, random forest and XGBoost. To evaluate the models, we calculated root mean square error (RMSE), mean square error (MSE), and mean absolute error (MAE) to evaluate accuracy and R² to evaluate explanatory power. Evaluation results are as follows. Linear regression (RMSE 268.15, MSE 71901.87, MAE 231.68, R² 0.92), decision tree (RMSE 108.89, MSE 11856.92, MAE 19.24, R² 0.99), random forest (RMSE 8.89, MSE 79.10, MAE 6.55, R² 0.99), XGBoost (RMSE 10.21, MSE 104.22, MAE 7.68, R² 0.99). The random forest model achieved the highest predictive ability. Improving the model's performance in the future is expected to contribute to lowering exposure among radiology technologists.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2006년도 추계학술대회
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• pp.618-629
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• 2006

This Paper is about optimizing preventive maintenance period of connected (r,s) out of(m,n) : F lattice system that one of multi-component system, (m,n) matrix failure of whole system is occurrence when parts that belong in (r,s) matrix part procession of parts arranged with procession are breakdown all. The preventive maintenance about system is very important viewing from system reliability and operational expense viewpoint. Preventive maintenance that misses a time calls big loss by system failure and expense of frequent full equipment is paid excessively in preventive maintenance itself but expense is paid much in preventive maintenance itself and whole expense escalation can be achieved preferably. Through this research, reliability model is constructed that do expense by smallest under full equipment policy chosen through comparison of each full equipment policy and preventive maintenance expense full equipment cycle and r ,s value are made using simulated annealing algorithm and simulated annealing algorithm that converge fast in multi-component system certified most suitable to optimization decision

• 한국정보통신학회논문지
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• 제8권7호
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• pp.1405-1409
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• 2004

본 논문은 H.264/AVC의 전체 부호화 과정의 큰 부분을 차지하는 블록 모드 결정의 연산량을 효율적으로 줄이면서도 영상의 화질을 감소시키지 않는 블록 모드 결정 알고리즘을 연구한다. 움직임 추정의 연산량 감소를 위해 매크로블록을 8$\times$8 보다 큰 블록 모드와 8$\times$8 보다 작은 블록 모드로 영역을 예측하여 모든 블록 모드 결정의 연산량을 줄인다. 여기서 8$\times$8 보다 작은 블록은 중요한 움직임 정보나 급격한 외각선의 경계를 포함 가능성이 높으므로 정확한 움직임 추정이 필요하다. 이를 위하여 8$\times$8 블록내 모든 블록 크기에 대해서 $RDC_{M\timesN}$를 구하고 가장 작은 $RDC_{M\timesN}$를 갖는 블록을 선택한다. 이때 $RDC_{M\timesN}$의 결정을 위하여 SATD와 이웃하는 탐색 블록의 화소값 평균의 차이를 이용한 움직임 강도를 사용하는 방식을 제안한다. 제안된 알고리즘은 매크로블록 내에서 블록 모드의 결정을 고속으로 수행하면서도 정확한 움직임 추정 및 보상을 가능하게 한다.

• 대한산업공학회지
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• 제21권3호
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• pp.345-356
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• 1995

The aim of this paper is to analyze the batch service queueing model M/M(a, b ; ${\mu}_k/1$) under general bulk service rule with mean service rate ${\mu}_k$ for a batch of k units, where $a{\leq}k{\leq}b$. This queueing model consists of the two-dimensional state space so that it is characterized by two-dimensional state Markov process. The steady-state solution and performane measure of this process are derived by using Matrix Geometric method. Meanwhile, a new approach is suggested to calculate the two-dimensional traffic density R which is used to obtain the steady-state solution. In addition, to determine the optimal service initiation threshold a, a decision model of this queueing system is developed evaluating cost of service per batch and cost of waiting per customer. In a job order production system, the decision-making procedure presented in this paper can be applicable to determining when production should be started.

• Journal of the Korean Statistical Society
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• 제1권1호
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• pp.18-24
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• 1973

Study on convexity has been improved in many statistical fields, such as linear programming, stochastic inverntory problems and decision theory. In proof of main theorem in Section 3, M. Loeve already proved this theorem with the $r$-th absolute moments on page 160 in [1]. Main consideration is given to prove this theorem using convex theorems with the generalized $t$-th mean when some convex properties hold on a real linear vector space $R_N$, which satisfies all properties of finite dimensional Hilbert space. Throughout this paper $\b{x}_j, \b{y}_j$ where $j = 1,2,......,k,.....,N$, denotes the vectors on $R_N$, and $C_N$ also denotes a subspace of $R_N$.

• Architectural research
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• 제7권1호
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• pp.11-18
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• 2005

In today's building industry the emphasis has been geared more towards construction, thus building maintenance and life cycle have been neglected until now. A direct result of this neglect is the rapid aging of building, which leads to more cost-effective decision making methods for the prolongation of building life span. The following study is conducted in the area of Daegu and Seoul in order to develop the estimation analysis method of the annual operation cost of the Korean high-rise condominiums for the cost-effective decision making support through mathematical and statistical analyses including the present value and standardized measurement corrections. Based on the assumption that the life expectancy of the high rise condominium is 50 years, initial cost is ￦421,212/$m^2$, and a total sum of yearly operation cost during life expectancy is ￦2,154,499//$m^2$), yearly accumulated operation cost is shown as below: $AOC=0.7097t^4-38.803t^3+806.95t^2+11045t-496.52$ ($R^2=0.98$) (Here, AOC = Accumulated Operation Cost, t = given years)

• 대한산업공학회지
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• 제34권1호
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• pp.98-107
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• 2008

The purpose of this paper is to present an optimization scheme that aims at minimizing the expected cost per unittime. This study considers a linear connected-(r, s)-ouI-of-(m, n):f lattice system whose components are orderedlike the elements of a linear (m, n)-matrix. We assume that all components are in the state 1 (operating) or 0(failed) and identical and s-independent. The system fails whenever at least one connected (r, s)-submatrix offailed components occurs. To find the optimal threshold of maintenance intervention, we use a simulatedannealing(SA) algorithm for the cost optimization procedure. The expected cost per unit time is obtained byMonte Carlo simulation. We also has made sensitivity analysis to the different cost parameters. In this study,utility maintenance model is constructed so that minimize the expense under full equipment policy throughcomparison for the full equipment policy and preventive maintenance policy. The full equipment cycle and unitcost rate are acquired by simulated annealing algorithm. The SA algorithm is appeared to converge fast inmulti-component system that is suitable to optimization decision problem.

• 재무관리연구
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• 제24권4호
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• pp.135-161
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• 2007

본 연구는 1997년 1월 1일부터 2006년 12월 31일까지 한국증권선물거래소의 유가증권시장과 코스닥시장에 상장된 IPO 기업을 대상으로 배당개시결정의 3가지 측면, 즉, 배당개시 여부, 배당수준 및 배당개시시점의 결정요인을 실증분석 하였으며, 주요한 분석결과는 다음과 같다. 첫째, 주요 배당이론, 즉, 잔여배당이론, 배당신호이론, 대리인이론, 케이터링이론, 거래비용이론 등에서 제시된 배당결정요인들은 IPO 기업의 배당개시결정에도 유의한 영향을 미친다. 성장기회 변수인 M/B 비율과 R&D지출 비율이 낮을수록, 수익성 변수인 EBITDA 비율이 높을수록, 거래량회전율이 낮을수록, 그리고 배당프리미엄이 높을수록 배당개시확률은 높아진다. 둘째, 주요 배당이론에서 제시된 배당결정요인 중에서 성장기회 변수와 수익성 변수는 IPO 기업의 배당수준결정에도 유의한 영향을 미친다. 즉, 성장기회 변수인 R&D지출 비율이 낮을수록, 그리고 수익성 변수인 EBITDA 비율이 높을수록 배당수준이 증가한다. 셋째, 배당개시확률을 증가시키는 요인들은 배당개시시점을 단축시키는 요인으로 작용한다. 즉, 성장기회 변수인 R&D지출이 낮을수록, 수익성 변수인 EBITDA 비율이 높을수록, 그리고 거래량 회전율이 낮을수록, 배당개시확률은 증가하고 배당개시시점은 단축된다. 특히, 수익성 변수인 EBITDA 비율 및 거래량회전율은 배당개시시점과 배당지급/연기 결정에 모두 유의한 영향을 미친다. 즉, EBITDA 비율이 높을수록 배당개시시점이 단축되고, 거래량회전율이 높을수록 배당개시시점이 연기된다. 또한 배당개시기업의 대부분은 IPO 후 2년 이내에 배당개시 여부를 결정한다. 따라서 기업이 IPO 후 2년 이내에 배당개시를 하지 않으면 그 이후에는 배당개시를 하지 않을 가능성이 많다.