멀티 콘센트용 변류기 및 과전류 검출 회로 설계

김용재,김민석,박규상,김재홍,Kim, Yong-Jae,Kim, Min-Seok,Park, Gyu-Sang,Kim, Jae-Hong 한국전자통신학회 2015 한국전자통신학회 논문지 Vol.10 No.8

멀티 콘센트의 과전류로 인한 과열을 방지하기 위한 보호방식으로는 주로 금속바이메탈 방식, 스위칭회로 방식, 마이크로컨트롤러(MCU)를 이용한 과전류 정밀제어 방식 등이 사용되어 오고 있다. 하지만 이러한 방식들은 보호회로가 과전류가 흐르는 전선에 병렬접속 함으로써 2차 화재의 위험이 있을 수 있으며 입력전압의 비선형 왜곡에 취약한 단점을 가지고 있다. 또한 기존의 방식들은 제품의 단가가 비교적 크게 올라가므로 충분한 시장성을 확보하기가 쉽지 않다. 본 논문에서는 이러한 문제를 해결하고자 과전류가 흐르는 전선에 비접촉식 관통형 변류기를 설계하고 변류기의 2차 유도전류를 이용하여 과전류를 감지하여 사용자가 과전류 상황을 인지할 수 있도록 LED 및 부저 회로를 통하여 시각 및 청각적 신호를 전달하는 기능을 구현한다. 실험 결과들로부터 제안된 회로는 매우 경제적이고 간단하면서도 안정적으로 동작함을 확인 할 수 있다. For the over-heat protection purpose in power strip devices, over-current detection/protection circuits, such as bimetal, switching circuit, and microprocessor-based relay circuit, have been widely setup in high-end products. Most of these circuits are connected to the power line in parallel and, thus, they are sensitive to the line voltage and current distortion. Moreover, these protection circuits are often costly and, therefore, it is hard to meet the commercial requirements. A low-cost over-current detection circuit with the contactless current transducer is designed and tested in this paper. The detection circuit is galvanically isolated from the power line and, thus, less sensitive to the line voltage distortion. The experimental results show that the proposed circuit accurately operates despite of its simple structure and low-cost electronic parts.

영산강의 식물플랑크톤 군집 동태

김용재,Kim, Yong-Jae 한국조류학회(藻類) 2003 ALGAE Vol.18 No.3

Dynamics of phytoplankton communities were investigated at five stations in Youngsan River from December 1995 to November 1996. Phytoplankton were identified to the total of 466 taxa, which were composed of 136 genera, 438 species, 27 varieties and 1 forma. The standing crops ranged 1,163-50,765 cells ${\cdot}ml^{-1}$ during the investigation periods. The variation of classes was in order to Chrysophyceae - Bascillariophyceae - Chlorophyceae at St. 1 and was only Bacillariophyceae at the other stations. The dominant species were 12 taxa including Aulacoseira ambigua, A. garnulata, Cyclotella meneghiniana, C. pseudostelligera, Chlorella vulgaris, Dinobryon sertularia, Flagilaria elliptica, Monoraphidium contortum, Micractinium pusillum, Nitzschia palea, Scenedesmus grahneisii and Stephanodiscus hantzschii f. tenuis. The standing crops of dominant species ranged from 10.6% to 94.7%. The genus Dinobryon in Chrysophyceae was dominant species at St. 1 in December 1995, but not recorded in the other months. The dominant species were composed with the planktonic diatoms from winter to spring and were the tychoplanktonic and the benthic species at St. 2-5 from summer to fall. The relationships between total standing crops and water temperature, pH, $NH_4$, $NO_2$, $NO_3$ and $PO_4$ showed low positive or negative coefficients. Stephanodiscus hantzschii f. tenuis had low positive or negative coefficients with water temperature, $NH_4$, $NO_2$, $NO_3$ and $PO_4$. The fluctuations of standing crops in the Youngsan river phytoplankton community were not caused by a single factor but controlled by the complex factors with interaction between phytoplankton community and envirowmental factors.

전기자 분산배치 PMLSM의 단부 코깅력 저감을 위한 전기자 스큐각의 영향 분석

김용재,김재홍,Kim, Yong-Jae,Kim, Jae-Hong 한국전자통신학회 2014 한국전자통신학회 논문지 Vol.9 No.2

영구자석 선형 동기 전동기는 회전기기에 비해 구조적으로 간단하여 보수 점검이 용이하고 정밀, 고속, 고추력화 등의 많은 장점을 가지고 있다. 하지만 반송경로 전장에 전기자를 설치해야 하는 구조적 특성으로 인해 반송경로가 길어지면 길어질수록 초기 설치비용이 상승하게 된다. 이러한 문제점을 해결하기 위해 전기자를 분산시켜 배치하는 방식을 제시하였으나 전기자를 분산시켜 배치할 경우 전기자 양 끝단에는 구조상 반드시 단부가 존재하게 되며 이러한 단부는 추력 맥동을 야기하는 코깅력을 크게 발생시켜 기기의 소음과 진동 및 기기의 성능 저하의 원인이 된다. 따라서 본 연구에서는 기기의 운전특성을 향상시키기 위해 전기자의 스큐에 따른 단부특성을 3D FEM 수치해석을 이용하여 파악하고 단부 코깅력을 가장 저감시키는 전기자 스큐를 제안하고자 한다. The permanent magnet linear synchronous motors facilitate maintenance, for it is structurally simple compare to rotating machine and has lots of advantage such as a precision control, high speed, high thrust and so on. However, it causes an increase of material cost because of structural characteristics that need to arranges the armature on the full length of transportation lines. Thus, in order to resolve this problem, we propose the discontinuous arrangement method of the armature but the edge always exists due to the structure when the armature is arranged discontinuously. Due to this edge, the cogging force is greatly generated and it causes thrust force ripple generating noise, vibration and decline of performance. Therefore, in this paper, we examined the characteristic of end edge according to the skew angle through 3-D numerical analysis using finite element method(FEM) and improved the operation characteristics.

낙동강 중,하류의 식물플랑크톤 군집의 월 변화

김용재,Kim, Yong-Jae 한국조류학회(藻類) 2004 ALGAE Vol.19 No.4

Monthly variations of phytoplankton communities were conducted to the investigation at five stations in mid and lower parts of the Nakdong River from December 1995 to November 1996. The phytoplankton communities were identified a total 456taxa which were composed of 136 genera, 427 species, 27 varieties and 2 forma. The standing crops of phytoplankton communities ranged from 2.7 to 52.8 (${\times}$10³)cells·ml$^{-1}$ during the investigation periods. Bacillariophyceae was the dominant classes at all stations. The dominant species were 7taxa and the standing crops of these ranged from 18.3 to 95.1% of the standing crops of phytoplankton communities. The dominant species in the mid parts (st. 1, 2) of this river system were benthic species such as Navicula gregaria, N. viridula var. rostellata and Nitzschia palea, however it was planktonic species (Stephan discus hantzschii, Golenkinia radiata) and meroplanktonic species (Aulacoseira ambigua, A. granulata) in the lower parts (st. 3, 4, 5). The seasonal variations of the dominant species in the lower parts were appeared to the planktonic species (S. hantzschii) from winter to spring, and were the meroplanktonic species (A. ambigua and A. granulata) in from summer to fall. The lower parts of the Nakdong river were entropic states because the dominant species were composed A. ambigua, A. granulate and S. hantzschii which were indicators of entropic water quality. The interrelationships between total standing crops and environmental factors(water temperature, pH, NH$_4$, NO$_2$, NO$_3$ and PO$_4$) were low positive or negative coefficients. S. hantzschii had low positive or negative relations with water temperature, NH$_4$, NO$_2$, NO$_3$ and PO$_4$. As the result, the variations of standing crops of phytoplankton were not caused by a single factor but controlled by the complex factors.

Bifurcating을 적용한 집중권 PMLSM의 보조극 설치에 관한 연구

김용재,Kim, Yong-Jae 한국전자통신학회 2012 한국전자통신학회 논문지 Vol.7 No.5

Recently, linear motors have been widely researched and have been increasingly used in various industrial applications. Especially, permanent magnet linear synchronous motors(PMLSMs) have been getting the spotlight in the transportation system. A PMLSM is structurally simple and has a lot of merits such as high speed, high thrust force, etc. However, in case of a long stator system which arranges armature to the full length of transportation lines, a PMLSM has some disadvantages such as the material cost increase and long manufacturing time. Hence, in order to overcome these problems, the PMLSM with stationary discontinuous armature structure and concentrated windings was proposed. However, this method occurs undesirable cogging force by outlet edge effect. The cogging force causes thrust force ripples and generates noise and vibration. Therefore, in this paper, we proposed installation method of auxiliary pole PMLSM with concentrated winding applying bifurcating in order to reduce cogging force by the outlet edge when the armature is placed in a discontinuous arrangement. Also, we have examined characteristics of outlet edge cogging force using 2-D finite element analysis(FEA). 현재 선형 전동기는 많은 연구가 진행되어 그 응용분야가 산업전반에 확대되고 있다. 이중 반송장치 분야에서 영구자석 선형 동기 전동기(Permanent Magnet Linear Synchronous Motor:이하 PMLSM)가 각광을 받고 있다. 영구자석 선형 동기 전동기는 구조적으로 간단하며 고속화 고추력화 등의 장점을 가지고 있지만 전기자를 반송경로 전장에 배치하는 지상 1차측 시스템을 장거리 반송장치에 적용하면 재료비용의 증가 및 제작시간 증가 등의 문제점이 발생한다. 따라서 전기자를 분산(불연속) 배치하는 방식이 제안되고 있다. 하지만 이러한 전기자 분산배치 방식은 구조적으로 단부가 존재하고 이러한 단부에 의해 코깅력이 발생한다. 이는 추력 맥동의 원인이 되며, 소음과 진동을 발생시킨다. 따라서, 본 연구에서는 전기자를 분산배치 할 경우 필연적으로 생기는 단부에 의한 코깅력을 저감하기 위해 Bifurcating을 적용한 집중권 PMLSM에 보조극 설치법을 제안한다. 또한 그에 따른 단부 코깅력 특성을 2차원 유한요소법(FEA)을 이용하여 분석하였다.

임하호의 (臨河湖) 식물성 플랑크톤 군집 분석

김용재,정준 ( Yong Jae Kim,Jun Chung ) 한국하천호수학회 1993 생태와 환경 Vol.26 No.3

This study investigated to the composition of phytoplankton community and its ecological factors in the Imha lake changed from the stream environment to the lake environment as the result by the construction of a multiple-purpose dam from Mar. to Dec. in 1992. Phytoplankton community was total 234 taxa composed of 7 class, 14 orders, 6 suborders, 39 families, 95 genera, 199 species, 25 variaties, 3 forma and 7 unidendifed species. The occurred taxa at each station and season ranged from 25 taxa at station 2 on May to 62 taxa at station 4 on May, which were very the wide variations at each station and season. The changes of standing crops were the maximum as 1.5×10^7unit/ℓat station 1 on Mar. and the minimum as 2.9×10^5unit/ℓat station 3 on Mar. Dominant Species were Achnanthes minutissima, Aulacoseira granulata var. angustissima, Cyclotella stelligera, Cymbella minuta var. silesiaca, Coelastrum cambricum, Phacotus lenticularis and Synedra delicatissima var. angustissima. The dominance index ranged from 0.15 to 0.76, and the diversity was very wide as the range from 0.23 to 1.05, also evenness diversed such as two index. The cluster analysis by similarity appeared the high relations with Aug. and Sept. at station 2 and the index was 0.88. Of the relationships between standing crops and physico-chemical factors, it was not the regularity between standing crop and chlorophyll concentration, and ranged from 0.89 at station 2 to negative index at other stations. Of dominant species, the relationships between Cyclotella stelligera and chlorophyll concentrations were the positive relations as up to 0.65 at all stations except to station 4.

보문호에서의 훈장말 속 ( 녹조강 ) 에 대한 계절적 변화

김용재,정준 ( Yong Jae Kim,Jun Chung ) 한국하천호수학회 1992 생태와 환경 Vol.25 No.4

This study compared the seasonal variations of the species composition and standing crops of the genus Pediastrum in the steady state and the nonsteady state of water environment in the Pomun Lake from November, 1990 to October, 1991. It was identified 15 taxa which were 8 species, 7 varieties in the genus Pediastrum from this lake. The variations of monthly taxa numbers were from 11 taxa in November, 1990 to 4 taxa in August, 1991. The variations of standing crops were from 7.5×10^4 unit/l in November, 1990 to 8×10^2 unit/l in August, 1991, respectively. It was a positive correlation between the standing crops and physico-chemical factors (e.g. pH, water temperature, transparency, NH_4- N, PO_4- P). Also, the chlorophyll-a concentration was closely correlated with the changes of standing crops. In the steady state of water environment, the regular seasonal variations were the autogenic changes by the self-activity of the genus Pediastrum, but in the nonsteady state, the irregular seasonalities were the allogenic changes by the external factors(e. g. influx of external polluted material, and vertical and horizontal mixing by a localized torriential downpour), and retarded the velocity and disturbed the courses of succession.

DCT 영역에서 영상의 임의 비율 크기 변환을 위한 새로운 알고리즘

김용재,이창우,Kim, Yong-Jae,Lee, Chang-Woo 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.2C

유비쿼터스 통신 환경에서는 영상의 다양한 형태의 변환이 필수적인데, 대부분의 디지털 영상은 DCT (Discrete Cosine Transform)를 기반으로 한 JPEG, MPEG 등의 표준 기법을 이용하여 압축되어 저장되어 있다. 본 논문에서는 DCT 영역에서 영상의 크기를 변환시키는 기존의 여러 가지 알고리즘들을 고찰하고 그 성능을 분석하며, 기존의 방법보다 더 우수한 성능을 보이는 DCT 영역에서의 영상 크기 변환 알고리즘을 제안한다. 제안하는 알고리즘은 DCT 영역에서 영상의 임의 크기 변환을 위해 여러 개의 $8{\times}8$ DCT 계수 블록을 변환 비율에 따라 변환식을 통하여 하나의 블록으로 변환하고 최적의 zero-padding 및 truncating을 위한 IDCT의 크기를 정하는 방법을 이용하여 영상 크기 변환의 성능을 높인다. 이것은 화소간의 상관도를 최대한 이용하여 DCT 계수를 구하고, 여기서 얻어진 DCT 계수 블록에서 원하는 비율에 따라 최적의 크기를 구함으로써 성능을 높이는 알고리즘이다. 그 성능을 원 영상과 축소하여 다시 확대시킨 영상의 PSNR 비교를 통하여 확인하였고, 제안하는 알고리즘은 특정 비율의 변환에 있어서 기존의 알고리즘을 포괄할 수 있는 방법임을 확인할 수 있었다. In Ubiquitous communication environment, various conversions of images are essential, and most digital images are compressed by standard methods such as the Joint Photographic Expert Group (JPEG) and Motion Picture Expert Group (MPEG) which are based on the discrete cosine transform (DCT). In this paper, various image resizing algorithms in the DCT domain are analyzed, and a new image resizing algorithm, which shows superior performance compared with the conventional methods, is proposed. For arbitrary-ratio image resizing in the DCT domain, several blocks of $8{\times}8$ DCT coefficients are converted into one block using the conversion formula in the proposed algorithm, and the size of the inverse discrete cosine transform (IDCT) is decided optimally. The performance is analyzed by comparing the peak signal to noise ratio (PSNR) between original images and converted images. The performance of the proposed algorithm is better than that of the conventional algorithm, since the correlation of pixels in images is utilized more efficiently.

보행자보호 시험용 Flex-PLI의 특성 및 소형차 대응 구조 연구

김용재,진욱,김동선,Kim, Yong Jae,Jin, Wook,Kim, Dong Sun 한국자동차안전학회 2012 자동차안전학회지 Vol.4 No.2

In 2014 Flex-PLIfor the pedestrian protection will be applied to NCAP test. The most significant feature of Flex-PLI is constructed with segmental bone cores for the femur and tibia regions. So it can be more reproducible by representing pedestrian injuries such as knee ligament and tibia injury during the pedestrian crash against vehicle. In this paper, Analyzed the characteristics of Flex-PLI through the structural analysis and the test results by using Flex-PLI for our compact vehicles. Finally countermeasures into compact vehicle were proposed to fulfill the injury criteria of Flex-PLI.

덕동호와 보문호의 식물플랑크톤에 대한 계절적 변화

김용재,김한순,정준 ( Yong Jae Kim,Han Soon Kim,Jun Chung ) 한국하천호수학회 1991 생태와 환경 Vol.24 No.4

The purpose of this study was to investigate the phytoplankton composition and agal biomass from Tokdong and Pomun lakes in Kyongju city, from May,1989 to April,1990. The authors have examined 139 taxa of the phytoplankton from Tokdong and Pomun lakes. These were composed of 5 classes, 10 orders, 3 suborders, 23 families, 50 genera, 110 species, 25 varieties and 4 forma. Agal biomass increased from 27 individuals/ml in January to 140 individuals/ml in November, at Tokdong lake and from 19 individuals/ml in January to 538 individuals/ml in August, at Pomun lake. Two peaks of chlorophyll-a concentration were observed in the surface water of both lakes, one in September and the other in February. Annual mean concentrations of chlorophyII-a were 4.6㎍/1 and 9.9㎍/1 in the surface water of Tokdong and Pomun lakes. Trophic states of both lakes were intermediate levels between oligotrohic and mesotrophic at Tokdong lake, and between mesotrophic and eutrophic at Pomun lake as the quantity of chlorophyll-a