• 한국국방경영분석학회지
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• 제30권2호
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• pp.108-121
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• 2004

This paper deals with a procedure of changing the current inspection & replacement periods for ROKAF aircraft parts. ROKAF is mostly operating aircraft of foreign makes, and takes maintenance actions according to Technical Orders(TO.) published by foreign aircraft manufacturers. Therefore ROKAF inspects and replaces specific parts at the time noticed from T.O.. These inspection and replacement periods are determined by manufacturers according to the standard operating environment and parts' durability. But the standard operating environment Is different from operator's environment. Because of this difference, the inspection and replacement periods have to be changed according to operators' operation environment. It is resonable that the manufacturer, having design materials and life test data of parts, changes those periods together with materials of operators' operation environment. But we have many difficulties in obtaining the design materials and life test data. Then this paper proposes a procedure of changing the periods of aircraft's parts with life data obtained during operating aircraft. For the reliability analysis, a software of RELEST (Reliability Estimation Version 1.0) is used.

• 한국CDE학회논문집
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• 제11권4호
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• pp.235-245
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• 2006

This paper proposes a CSG-based representation scheme for heterogeneous objects including multi-material objects and Functionally Graded Materials (FGMs). In particular, this scheme focuses on the construction of complicated heterogeneous objects guaranteeing desired material continuities at all the interfaces. In order to create various types of heterogeneous primitives, we first describe methods for specifying material composition functions such as geometry-independent, geometry-dependent functions. Constructive Material Composition (CMC) and corresponding heterogeneous Boolean Operators (e.g. material union, difference, intersection. and partition) are then proposed to illustrate how material continuities are dealt with. Finally, we describe the model hierarchy and data structure for computer representation. Even though the proposed scheme alone is sufficient for modeling all sorts of heterogeneous objects, the proposed scheme adopts a hybrid representation between CSG and decomposition. That is because hybrid representation can avoid the unnecessary growth of binary trees.

• 한국항만경제학회지
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• 제27권4호
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• pp.145-164
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• 2011

최근 동북아시아지역의 교역규모가 급성장함에 따라 동북아시아 경제권이 세계경제에서 점유하는 비중이 점차 늘어나고 있다. 이러한 대륙 국가들과의 주요 연결로서 가장 큰 구심점 역할을 하고 있는 것이 Trans Siberian Railway(TSR) 등이라고 할 수 있다. TSR 이용의 경우 국내 도로운송과 부산항과 극동 러시아 항만간 해상운송, 대륙횡단철도, 최종목적지 도착이후의 도로운송을 포함하고 있어 항공운송을 제외한 복합운송의 전 영역에 걸쳐 있으며 최근 들어 국내 철도 화물운송을 활성화시켜 대륙횡단철도와 연계하여 운영하는 것에 대한 방안도 활발하게 논의되고 있다. 따라서 본 연구는 첫째, 러시아 및 중앙아시아향(向) 화물 운송의 선봉장 역할을 하고 있는 우리나라 TSR Service Operator들의 특징 및 역할을 파악하고 둘째, TSR Service Operator의 SWOT 분석으로 대변되는 대내 외적인 환경 분석과 우리나라 TSR Service Operator의 현황을 분석하고 셋째, 이를 바탕으로 우리나라 TSR Service Operator가 지속적인 경쟁우위를 확보하고 유지할 수 있는 발전 방향을 제시하는데 그 목적이 있다.

• Journal of Dental Anesthesia and Pain Medicine
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• 제23권5호
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• pp.281-285
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• 2023

Background: Dentists bend needles prior to certain injections; however, there are concerns regarding needle fracture, lumen occlusion, and sharps handling. A previous study found that a 30-gauge needle fractures after four to nine 90° bends. This fatigue life study evaluated how many 90° bends a 30-gauge dental needle will sustain before fracture when bent using a needle guide. Methods: Two operators at Element Materials Technology, an independent testing, inspection, and certification company tested 48 30-gauge needles. After applying the needle guide, the operators bent the needle to a 90° angle and expressed the anesthetic from the tip. The needle was then bent back to a 0° angle, and the functionality was tested again. This process was repeated until the anesthetic failed to pass through the end of the needle due to fracture or obstruction. Each operator tested 24 needles (12 needles from each lot), and the number of sustained bends before the needle fracture was recorded. Results: The average number of sustained bends before needle failure was 40.33 (95% confidence interval = 37.41-43.26), with a minimum of 20, median of 40, and a maximum of 54. In each trial, the lumen remained patent until the needle fractured. The difference between the operators was statistically significant (P < 0.001). No significant differences in performance between needle lots were observed (P = 0.504). Conclusion: Our results suggest that using a needle guide increases the number of sustained bends before needle fracture (P < 0.000001) than those reported in previous studies. Future studies should further evaluate the use of needle guides with other needle types across a variety of operators. Furthermore, additional opportunities lie in exploring workplace safety considerations and clinical applications of anesthetic delivery using a bent needle.

• 대한수학회지
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• 제36권2호
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• pp.381-402
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• 1999

Let {Rn($\chi$)}{{{{ { } atop {n=0} }}}} be a discrete Sobolev orthogonal polynomials (DSOPS) relative to a symmetric bilinear form (p,q)={{{{ INT _{ } }}}} pqd$\mu$0 +{{{{ INT _{ } }}}} p qd$\mu$1, where d$\mu$0 and d$\mu$1 are signed Borel measures on . We find necessary and sufficient conditions for {Rn($\chi$)}{{{{ { } atop {n=0} }}}} to satisfy a second order difference equation 2($\chi$) y($\chi$)+ 1($\chi$) y($\chi$)= ny($\chi$) and classify all such {Rn($\chi$)}{{{{ { } atop {n=0} }}}}. Here, and are forward and backward difference operators defined by f($\chi$) = f($\chi$+1) - f($\chi$) and f($\chi$) = f($\chi$) - f($\chi$-1).

• 해양환경안전학회지
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• 제19권5호
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• pp.476-482
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• 2013

본 연구에서는 우리나라 각 항만 VTS에서 근무하고 있는 현직 관제사들을 대상으로 관제 구역 내에서 선박의 안전한 운항을 위해 선박과 선박 사이 및 선박과 육지(장애물)와의 최소 안전거리를 조사하여 VTS 관제의 효율성을 제고하는데 그 목적이 있다. 이러한 안전한 선박 통항을 위한 기초 자료를 제시하기 위해 우리나라 각 항만 VTS 관제사들이 관제하는 안전이격거리를 각 VTS 센터별, 개인별로 설문 조사 및 분석을 하고 실습선을 이용하여 선박 통항이 밀집되어 있는 싱가포르와 말라카 해협에서의 관제 거리를 서로 비교하여 VTS 관제사간의 최소안전거리에 어떠한 차이점이 있는지를 조사하였다. 설문조사 결과 같은 VTS 소속임에도 불구하고 개인별로 관제하는 최소안전거리에는 많은 차이가 있고 전체적으로 해안선이 완만한 동해항의 경우 관제 안전거리가 타 항만보다 컸으며 해안선이 복잡하고 어선 및 여객선의 입출항이 잦은 목포항이 관제 안전거리가 가장 짧음을 확인할 수 있었다. 또한 동일한 VTS에 근무하는 관제사들이 정형화된 관제 방법에 따라 관제를 할 수 있도록 항만의 자연조건이나 교통량에 적합한 모듈(Module)을 개발할 필요성이 필요하며 향후에는 표준관제절차 수립을 위한 전문가 집단의 충분한 논의가 있어야 할 것으로 사료된다.

• 농촌계획
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• 제19권2호
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• pp.173-181
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• 2013

The importance of human resources empowerment for operation and management is increasing for sustainable effects and improvement in mountain eco village development projects. This study aimed to understand the cognition characteristics of operator who works for mountain eco villages as part of the mountain village development and to suggest improvement methods in empowerment training aspects. The survey contained operator's empowerment and operator systems in mountain eco villages and the results were analyzed for the study. Operators who joined the mountain eco village operator training course by Korea Forest Service were conducted the survey on March 12th~13th in 2012 and March 13th~15th in 2013. 69 and 58 of questionnaires were collected respectively and analyzed for the study. T-test was applied to Intergroup cognition difference and regression analysis was used for influential factors in necessity of operator's role. Collected data was analyzed by statistical package programme SPSS 18.0 version. According to the comparison of empowerment cognition with contingent upon training experience, 'harmony with residents' showed significantly difference at p<0.05 level. In the recognition comparison for prospect of future mountain eco village development, 'various training experiences' was significantly difference at p<0.01 level between positive and negative prospect group. Regression analysis revealed that 'communication with village leader', 'harmony with residents', and 'idea related to the project' have an effect on necessity of operator's empowerment significantly. Based on the results, the study suggests improved directions for operator's empowerment training as a horizontal leader who conduces a mountain village.

• 대한수학회보
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• 제53권1호
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• pp.49-60
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• 2016

In this paper, we investigate the high order difference counterpart of $Br{\ddot{u}}ck^{\prime}s$ conjecture, and we prove one result that for a transcendental entire function f of finite order, which has a Borel exceptional function a whose order is less than one, if ${\Delta}^nf$ and f share one small function d other than a CM, then f must be form of $f(z)=a+ce^{{\beta}z}$, where c and ${\beta}$ are two nonzero constants such that $\frac{d-{\Delta}^na}{d-a}=(e^{\beta}-1)^n$. This result extends Chen's result from the case of ${\sigma}(d)$ < 1 to the general case of ${\sigma}(d)$ < ${\sigma}(f)$.

• Kyungpook Mathematical Journal
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• 제50권1호
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• pp.59-69
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• 2010

The main aim of this article is to introduce a new class of sequence spaces using the concept of n-norm and to investigate these spaces for some linear topological structures as well as examine these spaces with respect to derived (n-1)-norm. We use an Orlicz function, a bounded sequence of positive real numbers and some difference operators to construct these spaces so that they become more generalized and some other spaces can be derived under special cases. These investigations will enhance the acceptability of the notion of n-norm by giving a way to construct different sequence spaces with elements in n-normed spaces.

• 한국안전학회지
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• 제9권1호
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• pp.31-39
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• 1994

In this study, image processing were performed to recognize the shape of objects and find its center coordinate and direction to grisp the objects by the robot automatically. The proposed methods could be applied to objects even if light is reflected, and to identify the insides and outsides of objects by using the photo sensor and the difference of surface conditions. Also image segmentation is performed to the objects close to each other. These image processing methods will be increased the safety of operators by the automation of dangerous and hazardous machine works.