• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.55 no.4
• /
• pp.224-230
• /
• 2006

The conventional way to implement a bidirectional converter with boost/buck has been to use two general purpose PWM ICs with a single supply voltage. In this case, when one direction mode is in operation, the other is disabled and the output of the error amplifier of the disabled IC may be saturated to a maximum value or zero. Therefore, during mode transition, a circuit which can disable the switching operation for a certain time interval is required making it impossible to get a seamless transition. In this paper, the limitations of the conventional 42V/14V bi-directional DC/DC converter implemented with general current mode PWM ICs with a single supply voltage are reviewed and a new current mode PWM controller circuit with a dual voltage system is proposed. The validity of the proposed circuit is investigated through simulation. and experiments.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.26 no.5
• /
• pp.349-356
• /
• 2021

Permanent magnet synchronous motors are mainly used in the traction of electric vehicle and home application products including air-conditioners and refrigerators. For sensorless control without rotor position sensors, I-F control is applied for initial starting at low speeds, and mode is changed to sensorless control when the rotor speed is sufficiently accelerated for estimating rotor position. When the mode is changed to the sensorless control from the open-loop starting, the initial integral value of the speed controller should be considered by load condition; otherwise, the transition to sensorless control may fail. The sensorless transfer algorithm of PM synchronous motor based on load condition for smooth transition is proposed. The performance of the proposed sensorless transfer algorithm was verified by experiments.

• Journal of Korean Academy of Nursing Administration
• /
• v.20 no.2
• /
• pp.187-194
• /
• 2014

Purpose: The purpose of this study was to identify the perception of role transition from a student nurse to a registered nurse among senior year nursing students and to examine factors affecting their role transition. Methods: A descriptive survey with convenience sampling was conducted in four nursing colleges in Seoul, South Korea. Data were collected using a self-administrated questionnaire. Four instruments including role transition, self-esteem, interpersonal relationships and anxiety during clinical practicum were used and the students'demographics were also collected. A multiple logistic regression was used to identify predictors for the role transition. Results: A total of 233 nursing students were surveyed and final analysis was conducted utilizing 226 participants. Mean point of perceived role transition (5 point scale) was $3.34{\pm}0.44$. In a multiple regression model, high self-esteem, good interpersonal relationships, low anxiety during clinical practicum, and high satisfaction in college life were significant predictors of a smooth transition (Adj. $R^2$=.32, F=22.28, p<.001). Conclusion: The findings suggest that role transition from a student nurse to a registered nurse is facilitated through the establishment of programs to improve self-esteem and interpersonal relationships and to reduce anxiety during clinical practicum.

• Journal of the International Relations & Interdisciplinary Education
• /
• v.2 no.2
• /
• pp.1-8
• /
• 2022

In March 2021, the <Guidance on Promoting the Scientific Interface between Kindergarten and Elementary School> issued by the Ministry of Education of China clearly pointed out that it is necessary to adhere to child oriented. This goal of this policy is based on the idea of "living education" proposed by Mr. Heqin Chen in 1940, which indicates that a true understanding of children is necessary before talking about educating them. The core goal of "bidirectional articulation" is to strengthen the sense of articulation between kindergartens and elementary school, scientifically prepare for and adapt to school enrollment, and promote the smooth transition of children. Moreover, the <Guidance Points for Kindergarten Readiness Education> and the <Guidance Points for Elementary School Adaptation Education>, which were released at the same time as the <Guidance on Promoting the Scientific Interface between Kindergarten and Elementary School>, also place special emphasis on the cultivation of children's life preparation and adaptability. The aim of the bidirectional articulation "bridging" is to realize a two-way exchange of curriculum between kindergarten and elementary school, and to reform the curriculum at three levels through the curriculum spirit of "gamification", the continuous curriculum structure, and the developmental curriculum evaluation.

• Journal of the Korean Society of Visualization
• /
• v.12 no.3
• /
• pp.15-20
• /
• 2014

Direct numerical simulation (DNS) dataset of a turbulent boundary layer (TBL) with a step change from smooth to rough surface is analyzed to examine spatially developing flow characteristics. The roughness elements are periodically arranged two-dimensional (2-D) spanwise rods with a streamwise pitch of ${\lambda}=8k$ ($=12{\theta}_{in}$), and the roughness height is $k=15{\theta}_{in}$, where ${\theta}_{in}$ is the inlet momentum thickness. The step change is introduced $80{\theta}_{in}$ downstream from the inlet. For the first time, full images from the DNS data with the step change from the smooth to rough walls is present to get some idea of the geometry of turbulent coherent structures over rough wall, especially focusing on their existence and partial dynamics over the rough wall. The results show predominance of hairpin vortices over the rough wall and their spanwise scale growth mechanism by merging.

• Journal of Biomedical Engineering Research
• /
• v.32 no.3
• /
• pp.251-256
• /
• 2011

Virtual colonoscopy is favored over conventional colonoscopy because its non-invasive procedure can avoid complications that may happen in a conventional approach and because it can cleanse colon electronically instead of uncomfortable conventional colon cleansing. Electronic Colon Cleansing(ECC) has to deal with not only removing tagged fecal material but also recovering Partial Volume Effect(PVE) due to tagging material. This paper proposes an ECC method restoring inherent natural PVE while previous approaches focused only on reducing PVE due to tagged fecal material. The proposed method reduces PVE using 3-dimensional adaptive density correction and then replaces tagged fecal material into air. Next, it generates natural PVE for the replaced air adjacent to soft tissue and finally makes smooth transition of gray values for soft tissue adjacent to the replaced air. The proposed method applied to eleven patient data, and showed promising results.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.2
• /
• pp.112-122
• /
• 1995

While many surfaces such as automobile outer panels, ship hulls and airfoils are characterized by their smooth, free-form shapes, a far larger class of functional surfaces are characterized by highly irregular, multi-featured shapes consisting of pockets, channels, ribs, etc. In constaract to the design of aesthetic, free-form surfaces, functional surface design can perhaps best be viewed as a process of assembling a collection of known component surfaces to form a single compound surface. In this paper, we presents a feature-based functional surface modeling method. A single feature involves a secondary surface, which we must join to a primary surface with a smooth transition between two boundary courves. Through recursive blending of a secondary surface with the primary surface, the mullti-featured surface is represented. After constructing a compound surface, we generate the Z-map for NC machining of the surface. Offsetting the Z-map using the inverse offsetting technique, we get CL tool paths with out gouging.

• Annual Conference on Human and Language Technology
• /
• 2003.10d
• /
• pp.134-136
• /
• 2003

본 논문은 Grosz et al(1995)의 중심화이론(centering theory)을 바탕으로 목적어의 생략의 동기를 설명할 수 있는가를 검증하였다. 한국의 민담에 나타난 431개의 절과 신문사설 249개의 절을 분석한 결과 공목적어(zero object)의 17%만이 중심유지변이(continue transition)에 사용되었으며, 이는 중심화이론의 기존 세 가지 제약만으로는 공목적어의 분포를 설명할 수 없음을 보여주는 것이다. 본 연구에서는 중심화이론 내에서 공목적어의 분포를 설명하기 위하여 Kameyama(1998)의 평행선호조건(Parallelism Preference Condition)을 도입할 것을 제안하였다. 평행선호조건의 도입은 세 가지 측면에서 지지된다. 첫째, 중심변이 개념만으로 설명이 불충분한 공목적어의 분포를 중심화이론 내에서 설명할 수 있다. 둘째, 순조로운 중심이동변이(smooth-shift transition)에 나타나는 공주어의 분포를 설명할 수 있다. 셋째, 평행선호조건은 공명대명사의 해석뿐만 아니라 시제의 생략이나 동사의 생략을 설명하기 위해서 독립적으로 지지되는 조건이다.

• Journal of international Conference on Electrical Machines and Systems
• /
• v.1 no.2
• /
• pp.64-69
• /
• 2012

This paper presents a hybrid pulse width modulation (PWM) method under low switching frequency conditions based on space vector PWM (SVPWM) and selective harmonic eliminated PWM (SHEPWM), which use asynchronous carrier modulation SVPWM at low frequency, and SHEPWM at high frequency, a square wave after rated conditions. A transitive strategy is proposed to realize a smooth transition of individual modes including SVPWM, SHEPWM and square waves. Experimental results confirm this hybrid modulation method and their transition are reasonable and proper.

• Journal of Information Technology Applications and Management
• /
• v.15 no.3
• /
• pp.43-59
• /
• 2008

This paper studies small and medium sized financial agency's management states that take advantage of the Korea Federation of Saving Bank's data. It also presents the management state and the decision-making model that monitors progressive insolvency by standardizing transfer path between relevant groups. With this in mind, we extracted explanatory variables for predictions of insolvency by using existing studies of document related insolvency. First of all, we designed a state model based on demarcated groups to take advantage of the self organizing map that groups in line with a neural network. Secondly, we developed a transition model by standardizing the transfer path between individual banks in a state model. Finally, we presented a decision-making model that integrated the state model and the transition model. This paper will provide groundwork for methods of insolvency prevention to businesses in order for them to have a smooth management system in the financial agencies.