• Journal of Korean Neurosurgical Society
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• 제67권3호
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• pp.308-314
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• 2024

Vein of Galen aneurysmal malformation is one of important pediatric arteriovenous shunt diseases, especially among neonates and infants. Here, early history of the disease identification, basic pathoanatomy with a focus on the embryonic median prosencephalic vein, classification and differential diagnoses, and recent genetic studies are reviewed.

• 한국소음진동공학회논문집
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• 제14권5호
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• pp.424-431
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• 2004

An implicit direct-time integration method for obtaining transient responses of general dynamic systems is described. The conventional Newmark method cannot be directly applied to state-space first-order differential equations, which contain no explicit acceleration terms. The method proposed here is the state-space Newmark method that incorporates the average velocity concept, and can be applied to an analysis of general dynamic systems that are expressed by state-space first-order differential equations. It is also readily coded into a program. Stability and accuracy analyses indicate that the method is numerically unconditionally stable like the conventional Newmark method, and has a period error of 2nd-order accuracy for small damping and 4th-order for large damping and an amplitude error of 2nd-order, regardless of damping. In addition, its utility and validity are confirmed by two application examples. The results suggest that the proposed state-space Newmark method based on average velocity be generally applied to the analysis of transient responses of general dynamic systems with a high degree of reliability with respect to stability and accuracy.

• Journal of Advanced Marine Engineering and Technology
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• 제16권4호
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• pp.50-59
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• 1992

The paper presents a digital speed control approach of induction motor systems by using a digital servo control method and a well-known second order differential equation as model. The basic concept of using the modeling equation stated in the above is induced from the control theory stand point such that we can describe usually the motor system connected by inverter, generator and load etc, just as a mechanical system to be controlled. The concept does not demand us the complicated vector-based modeling equation adopted in the traditional methods for the speed control of induction motor. Futhermore, the proposed speed control system can be treated as a single input and single output system. The effectiveness of the servo control system obtained by the above-mentioned design concept is illustrated by the experimental results in the presence of both step reference changes and load variations. It is observed from the experimental results that the steady state-error of the experimental set up becomes zero after some regulation time and the induction motor system is robust in spite of reference signal changes and load variations.

• 대한수학교육학회지:학교수학
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• 제18권2호
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• pp.277-300
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• 2016

미분에 관한 주요 문제점으로 미분 개념이 공식처럼 다루어져 기초적 지식이 결여되어 있으며, 정형화된 계산 및 활용 문제를 해결하는 데에는 익숙하지만 비정형의 새로운 문제를 해결하는데 있어서는 그렇지 못함이 지적되고 있다. 선행 연구들은 주로 학습자 오류, 교재 구성, 지도 방법 등에 관심을 두고 이의 해결 방안을 제시하는데 중점을 두어 온 반면, 실험수업을 통한 양 질적 연구는 그다지 활발히 이뤄지지 않아 왔다. 이에 따라, 본 연구에서는 우선 '이해'의 의미를 가늠하고 미분 개념을 이해한다는 것이 무엇인지를 탐색하고, 그 결과에 맞춰 역사 발생적 원리 및 공학적 도구를 활용하여 미분계수와 도함수 내용의 이해를 돕기 위한 수업지도안을 마련하고자 하였다. 또, G광역시의 S고등학교 1학년에 재학 중인 총 68명의 학생들을 대상으로 통제집단 설계를 적용하여 실험수업을 실시하였다. 이때, 검사 도구는 '학습이해도'와 '학습만족도' 영역으로 구성하였으며, 'SPSS 21.0 Ver'를 사용하여 사후검사 결과를 분석하고 그 결과를 토대로 미분 개념의 이해를 높이기 위한 몇몇 지도 방안을 제시하고자 하였다.

• 대한가정학회지
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• 제44권3호
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• pp.79-89
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• 2006

The purpose of this study was to determine the differences of aggression and its predictors among Korean, Korean-Chinese and Chinese adolescents. The subjects were 529(176 Korean, 168 Korean-Chinese, 185 Chinese) 9th graders from Yanji in China and Korea. Data on aggression, self-concept, attachment to mother, relationship with teachers, and victimization from peers were collected with questionnaires and analyzed by t-test, ANOVA, and multiple regression. The results showed that Korean adolescents reported the highest and Chinese adolescents the lowest on aggression. There were gender differences in proactive aggression among Chinese adolescents, and on reactive aggression among Korean adolescents. Among Korean adolescents, no gender difference was revealed. The influences of self-concept, attachment to mother, relationship with teachers, and victimization from peers differed among the groups: While attachment to mother was a significant predictor for Chinese adolescents' aggression, relationship with teachers was a significant predictor for that of Korean-Chinese adolescents', and victimization from peer was a significant predictor for that of Korean adolescents'. The differential influence of race and culture to adolescents' aggression was discussed.

• 대한가정학회지
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• 제43권5호
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• pp.163-181
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• 2005

This study compared influential factors on adolescent's (10-16 years of age) self-concept in Korean-chinese and Korean cultures. The influence of parenting, peer relationship, and teacher's support on the development of children's and adolescent's self-concept was assessed with Korean-Chinese and Korean elementary, middle, and high school students. The subjects were 210 Korean-Chinese children and 300 Korean-Chinese adolescent from Shenyang, China, and 280 Korean children and 400 Korean adolescents from Seoul and Ulsan, Korea. Data were analyzed by t-test, factor analysis, and multiple regression. The results revealed differential influences of factors between the two cultures. Korean-Chinese children's self-concepts were influenced by teacher's support and parenting, while Korean children's self-concepts were significantly influenced tv their peer relationships and teacher's support. Korean-Chinese adolescent's! self-concepts were influenced tv teacher's support and parenting, while Korean adolescent's self-concepts were influenced by parenting and teacher's support.

• 대한교통학회지
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• 제20권5호
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• pp.67-79
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• 2002

교통량, 교통밀도, 교통류 속도 등, 교통류 변수에 대한 현재까지의 불확실한 정의와 연속적 파동방정식의 거시적 교통류 해석상의 문제점을 지적하고 이를 개선하기 위해 교통류 변수들에 대한 새로운 확률적 정의를 제시하고 이들의 성격을 규명하였다. 이러한 새로운 교통류 변수들에 대한 새로운 정의를 바탕으로 미시적 운전자 행동을 세밀하게 수용할 수 있고 많은 교통환경에서 연속적 파동 방정식을 대체하여 교통류 변수들과 통행시간을 예측할 수 있는 미분방정식 체계를 확률 미분방적식을 이용하여 도출하였다. 도출된 미분 방정식을 단일 차량의 시공 괘적에 적용해 보았다.

• 한국정보과학회논문지:시스템및이론
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• 제31권5_6호
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• pp.288-296
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• 2004

본 논문은 미분오차 척도를 이용하여 메쉬를 간략화 하는 새로울 알고리즘을 제안한다. 많은 간략화 알고리즘은 거리 오차 척도를 이용하였으나, 거리 오차 척도는 높은 곡률을 갖는 동시에 작은 거리오차를 갖는 지역에 대해서는 메쉬 간략화를 위한 정확한 기하학적 오차 측정이 어렵다. 본 논문은 간략화를 위해 새로운 오차 척도인 미분 오차 척도를 제안한다. 미분 오차 척도란 거리 오차 척도와 거리 오차의 1차 미분인 탄젠트 오차 척도, 그리고 거리 오차의 2차 미분인 곡률 오차 척도를 합하여 정의된 오차척도로서, 모델의 특징 부분의 형상을 최대한으로 보존 가능하다. 메쉬는 이산 표면이지만 알지 못하는 부드러운 표면의 불연속선형 근사로 표현될 수 있고, 이산 표면은 미분이 추정 가능하므로 미분 오차 척도라는 새로운 개념을 도입할 수 있다. 본 간략화 알고리즘은 반복적인 모서리 축약(Edge Collapse)에 바탕을 두고 있고, 미분 오차 척도를 이용하여 기하학적으로 원래의 형상이 잘 유지되는 새로운 점의 위치를 찾을 수 있다. 본 논문에서는 기존 방법보다 더 작은 기하학적인 오차와 높은 품질의 간략화 된 모델의 예를 보여준다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2182-2186
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• 2003

This paper presents the differential type resonant accelerometer (DRXL) and its performance test results. The DRXL is the INS grade, surface micro-machined sensor. The proposed DRXL device produces a differential digital output upon an applied acceleration, and the principle is a gap-dependent electrical stiffness variation of the electrostatic resonator with torsion beam structures. Using this new operating concept, we designed, fabricated and tested the proposed device. The final device was fabricated by using the wafer level vacuum packaging process. To test the performance of the DRXL, a nonlinear self-oscillation loop is designed using describing function technique. The oscillation loop is implemented using discrete electronic elements. The performance test of the DRXL shows that the sensitivity of the accelerometer is 12 Hz/g and its long term bias stability is about $2mg(1{\sigma})$. The turn on repeatability, bandwidth, and dynamic range are 4.38 mg, 100 Hz, and ${\pm}\;70g$, respectively.

• Industrial Engineering and Management Systems
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• 제14권3호
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• pp.299-311
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• 2015

Nowadays, the distribution centres aim to reduce costs by reducing inventory and timely shipment. Cross docking is a logistics strategy in which products delivered to a distribution centre by inbound trucks are directly unloaded and transferred to outbound trucks with minimum warehouse storage. Moreover, on-time delivery in a distribution network becomes very crucial especially when several distribution centres and customers are involved. Therefore, an efficient truck scheduling is needed to synchronize the delivery throughout the network in order to satisfy all stake-holders. This paper presents a mathematical model of a mixed integer programming for door assignment and truck scheduling in a multiple inbound and outbound doors cross docking problem according to Just-In-Time concept. The objective is to find the schedule of transhipment operations to simultaneously minimize the total earliness and total tardiness of trucks. Then, a multi-objective differential evolution (MODE) is proposed with an encoding scheme and four decoding strategies, called ITSH, ITDD, OTSH and OTDD, to find a Pareto frontier for the multi-door cross docking problems. The performances of MODE are evaluated using 15 generated instances. The numerical experiments demonstrate that the proposed algorithm is capable of finding a set of diverse and high quality non-dominated solutions.