• Journal of Power Electronics
• /
• 제15권2호
• /
• pp.544-554
• /
• 2015

This paper presents a steady-state operation analysis of full-bridge series-resonant inverters focusing on the distorted load current due to low-quality-factor resonant circuits in induction heating and other applications. The regions of operation based on the zero-voltage switching (ZVS) and non-zero-voltage switching (NON-ZVS) operations of the asymmetrical voltage-cancellation control technique are identified. The effects of a distorted load current under a wide range of output powers are also analyzed for achieving a precise ZVS operating region. An experimental study is performed with a 1kW prototype. Simulation and experimental studies have confirmed the validity of the proposed method. An efficiency comparison between the variable frequency method and the conventional fixed-frequency method is provided.

• 조명전기설비학회논문지
• /
• 제20권8호
• /
• pp.54-62
• /
• 2006

3상 4선식 전원공급 시스템에서 단상 및 3상 부하의 운전하에서 전압 불평형은 부하의 불평형 운전에 의해 발생되고, 전류 불평형은 떨어진 전압 품질에 의해 더욱 심해진다. 에너지 변환장치로 사용되는 여러 형태의 컨버터는 3상 4선식 배전시스템에 직접적으로 고조파 전류를 주입함으로서 고조파 왜란을 증가시킨다. 고조파 전류는 전동기 출력 토크를 감소시키고, 전동기를 과열 또는 소음을 증가시키며 회전자에 토크 맥동을 증가하여 기계적인 공진과 진동을 발생하는 등 여러 가지 부작용을 낳고 있다. 따라서 본 논문은 3상 4선식 배전시스템에서 선형 및 비선형 부하의 혼합 운전시 불평형과 고조파 성분에 의해 유도전동기의 특성 변화에 대한 연구로서 선형 단독운전, 비선형 부하 결합에 따른 특성 변화를 해석한 것으로서 단상 비선형 부하의 추가 운전시 5 고조파 필터로도 저감이 어려운 고조파로 인해 토크 맥동 횟수는 줄고 리플값은 증가함을 확인할 수 있었다.

• 융합보안논문지
• /
• 제19권4호
• /
• pp.13-22
• /
• 2019

본 연구는 사이버작전을 전문적으로 수행하지 않는 비(非)사이버작전부대 장교들을 위한 교육체계를 개발하고 방향성을 제안하기 위한 연구이다. 사이버작전을 합동작전으로 수행하기 위해서는 비(非)사이버작전부대 장교들도 사이버작전을 알아야하나 이들을 위한 교육체계는 현재 군(軍)에는 없으며, 이에 대한 선행연구 또한 거의 없어 해당 분야의 연구가 필요하다. 따라서, 비(非)사이버작전부대 장교 교육체계는 사전에 실시한 관련 문헌연구를 기반으로, 교육체계를 구성할 수 있는 5가지 항목 즉, 교육의 필요성, 교육대상, 교육목표 및 내용, 교육과정에 관한 사항을 개발하였다. 또한, 관련 전문가들에게 델파이방법으로 각 항목의 타당성을 확인하였다. 그 결과, 일부 향상의 필요성도 보였으나, 전체적으로 적합함을 보였다. 향후에는 이 연구를 바탕으로 세부 교육프로그램 개발이 개발될 수 있다.

• Journal of Chest Surgery
• /
• 제23권4호
• /
• pp.731-735
• /
• 1990

Simultaneous and non simultaneous bilateral spontaneous pneumothorax patients[273] were reviewed retrospectively from April 1986 to March 1990 in the Dept. of Thoracic and Cardiovascular Surgery, Kyung Hee University Medical College. The incidence of bilateral spontaneous pneumothorax was 13.6%[37] and sexual distribution was male dominant [Male:33, Female:4]. The patients were classified into three major groups according to therapeutic methods: Group I [7]; who were treated with simultaneous bilateral operation for unilateral recurred spontaneous pneumothorax through median sternotomy. Mean age was 20.7 years[17 \ulcorner28] and follow up duration was 7.7 months [3 weeks \ulcorner2 years]. Group II [23];who were treated with staged lateral thoractomy, unilateral thoracotomy and non simultaneous contralateral closed thoracostomy, or simultaneous or non simultaneous bilateral closed thoracostomy. Mean age was 28.6 years [17 \ulcorner56] and follow up duration was 9.8 months[one week \ulcorner3.5 years]. Group III[10] ;who were treated with simultaneous bilateral operation for simultaneous or non simultaneous bilateral spontaneous pneumothorax through median sternotomy. Mean age was 21.4 years[17 \ulcorner28] and follow up duration was 12.8 months[2 weeks \ulcorner2.7 years]. Among the patients managed through median sternotomy simultaneously [Group I and III], there were visible blebs or bullous changed lesions mainly in the apicoposterior segment bilaterally in 15 patients[88.2%] Postoperative complications were 3 cases in Group II [wound infection:2 cases, temporary left wrist drop: one case] but none in Group I and III. Spontaneous pneumothorax recurred in 2 cases, one in Group II and another in Group III but none in Group I. 12 cases of 94 patients[12.8%o] who were treated with unilateral thoracotomy needed contralateral thoracotomy mean 14.9 months[7.5 \ulcorner 25 months] later. Mean age was 20.9 years [17 \ulcorner28]. In conclusion, simultaneous bilateral operation through median sternotomy should be considered in managements of spontaneous pneumothorax, especially in late teens and early twenties except young women for cosmetic reasons.

• Archives of Plastic Surgery
• /
• 제32권6호
• /
• pp.727-732
• /
• 2005

The treatment of wounds of the lower extremity caused by diabetes or vascular dysfunction remains a difficult problem for the plastic surgeon. The use of negative pressure in wound healing is a relatively new method to facilitate chronic wound healing by secondary healing. The use of vacuum-assisted closure(VAC) system is purposed to reduce local edema, increase regional blood flow, enhance epithelial migration, preserve a moist wound environment, reduce bacterial colonization, promote granulation tissue formation, and mechanically enhance wound closure. The VAC also can be used as a dressing for anchoring an applied split thickness skin graft. We reviewed the data from 20 consecutive patients with non-healing wound in lower extremity at Dong-A University from March 2002 to December 2004. We used the VAC in 20 patients and compared the results with the control group. In the VAC using group, mean application duration was about 3 weeks and dressing change was done every other day. The follow-up period of patients ranged from 3 months to 30 months with a mean of 17 months. The points of comparison with control group are wound size, granulation tissue proliferation rate, operation method, preoperative time, postoperative healing time, complication, and cost. With those points, we propose to approve the efficiency of the VAC in non-healing wound. As a result, the VAC used in non-healing wound decrease wound size, accelerate granulation tissue formation, do a wound closure with less invasive operation method, make less postoperative complication, can make operation time shorter. Therefore it is cost effect. Our results demonstrate the usefulness of VAC as an adjunct in management of chronic wounds with other extrinsic factors.

• 융합보안논문지
• /
• 제22권4호
• /
• pp.53-63
• /
• 2022

국방부는 2015년부터 부사관학군단(RNTC) 제도를 전문대학을 대상으로 다시 도입하여 5년 동안 시범 적용을 하게 되었다. 그 배경으로는 군의 우수 부사관 획득이 어려우며 인력 운영 수준이 저조하기 때문이다. 부사관학군단(RNTC) 제도 시행을 통해 군은 전문대학에서 다양한 전공 분야별 우수한 자원으로 부사관을 안정적으로 획득하길 기대하고, 전문대학은 입시와 취업에 긍정적인 성과를 기대하였다. 그러나 시범운영 결과를 분석해 볼 때 기대했던 성과를 거두지 못했다고 평가할 수 있다. 즉, 부사관학군단(RNTC) 후보생 모집 홍보, 선발, 학군단 운영, 군과 전문대학의 협조체계등에서 제도 시행의 목적을 달성할 수 있도록 제도의 보완 및 개선이 필요함을 발견할 수 있었다. 따라서 본 연구에서는 전문대학에서 부사관학군단(RNTC) 제도가 원활하게 정착되어 군과 전문대학에서 기대하는 성과를 얻을 수 있도록 제도와 운영시스템 보완을 위한 발전방안을 제시하였다.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2002년도 춘계 학술발표회 논문집
• /
• pp.239-249
• /
• 2002

The Turbine Building of nuclear power plant is classified as non safety-related structure. During the operation, there may be possibility the original licensing basis would be changed, which makes non safety-related structure safety-related. Such a change in regulation requires utility to perform seismic qualification for the existing structure and their facilities. Thus it is meaningful to evaluate seismic margin of the existing non-qualified building structure. In addition, in this paper it is shown that a modification to the structure can enhance their seismic capacity.

• East Asian mathematical journal
• /
• 제28권3호
• /
• pp.281-285
• /
• 2012

In this paper, the concept of *-prime ideals in non-associative near-rings is introduced and then will be studied. For this purpose, first we introduce the notions of *-operation, *-prime ideal and *-system in a near-ring. Next, we will define the *-sequence, *-strongly nilpotent *-prime radical of near-rings, and then obtain some characterizations of *-prime ideal and *-prime radical $r_s$(I) of an ideal I of near-ring N.

• 한국산학기술학회논문지
• /
• 제12권6호
• /
• pp.2607-2615
• /
• 2011

본 연구는 심폐소생술 시행 시 구령집단과 비구령집단 간의 심폐소생술 정확도 비교를 통하여 심폐소생술 시행에 효율성과 정확성을 높이고자 한다. 본 연구는 G도에 소재 대학생 62명(비구령집단 31명, 구령집단 31명)을 편의추출 하였으며, 조사기간은 2010년 10월 7일부터 10월 21일까지 이루어졌다. 분석방법은 SPSS WIN(Version 12.0) 프로그램을 이용하여 분석하였다. 연구결과 심폐소생술 시행 시 비구령집단이 구령집단보다 여러 영역에서 인공호흡과 가슴압박에 대한 심폐소생술의 정확도가 높게 나타났다. 이를 바탕으로 차후 심폐소생술 교육과 술기를 수행함에 있어서 비구령방법을 적용해 볼 필요가 있다. 그리고 응급상황에서 구령방법과 비구령방밥 간의 효과성에 대한 지속적 연구도 필요하다.

• 대한인간공학회지
• /
• 제31권4호
• /
• pp.515-523
• /
• 2012

Objective: The aim of this study is to investigate users' intuitive stereotypes on non-touch gestures and establish the gesture dictionary that can be applied to gesture-based interaction designs. Background: Recently, the interaction based on non-touch gestures is emerging as an alternative for natural interactions between human and systems. However, in order for non-touch gestures to become a universe interaction method, the studies on what kinds of gestures are intuitive and effective should be prerequisite. Method: In this study, as applicable domains of non-touch gestures, four devices(i.e. TV, Audio, Computer, Car Navigation) and sixteen basic operations(i.e. power on/off, previous/next page, volume up/down, list up/down, zoom in/out, play, cancel, delete, search, mute, save) were drawn from both focus group interview and survey. Then, a user participatory design was performed. The participants were requested to design three gestures suitable to each operation in the devices, and they evaluated intuitiveness, memorability, convenience, and satisfaction of their derived gestures. Through the participatory design, agreement scores, frequencies and planning times of each distinguished gesture were measured. Results: The derived gestures were not different in terms of four devices. However, diverse but common gestures were derived in terms of kinds of operations. In special, manipulative gestures were suitable for all kinds of operations. On the contrary, semantic or descriptive gestures were proper to one-shot operations like power on/off, play, cancel or search. Conclusion: The touchless gesture dictionary was established by mapping intuitive and valuable gestures onto each operation. Application: The dictionary can be applied to interaction designs based on non-touch gestures. Moreover, it will be used as a basic reference for standardizing non-touch gestures.