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단상 유도전동기의 구속운전조건에서 화재 위험성에 관한 연구
지홍근(Hong-Keun Ji),송재용(Jae-Yong Song) 한국화재소방학회 2020 한국화재소방학회논문지 Vol.34 No.2
본 논문에서는 단상 유도전동기의 구속운전조건에서 화재 위험성에 관하여 기술하였다. 일반적으로 전동기의 고장 발생은 회전자의 회전 불량 등으로 인한 구속운전조건의 형태로 나타난다. 전동기의 기동 시에는 정격전류의 약2∼15배에 달하는 큰 돌입전류가 흐르게 되는데 단상 유도전동기에서 구속운전조건이 발생하게 되면 돌입전류에 준하는 전류가 지속적으로 고정자권선을 통해 흐르게 된다. 구속운전조건에서 고정자권선을 통해 흐르는 과전류에 의해 고정자 권선 내부의 온도가 상승하고, 최종적으로 절연물을 매개로 화재로 이어지는 특징이 나타난다. 본 논문에서는 임의로 구속운전조건을 만들고, 이때 고정자권선에 흐르는 과전류의 크기 및 온도 상승을 측정하였다. 실험결과로부터 구속운전조건에서는 정격전류에 비해 약 7배의 과전류가 발생하였으며, 고정자권선 내부의 온도가 약 300℃ 정도에서 화재로 진전되는 것을 확인하였다. In this paper, the fire risk of a single-phase induction motor under a locked-rotor condition is described. In general,motor failure occurs in the locked-rotor condition owing to poor rotation of the rotor. Large inrush current flows when amotor starts, which is approximately 2-15 times larger than the rated current. In a single-phase induction motor under thelocked-rotor condition, a large current that corresponds to the inrush current flows continuously through the stator winding. Such an overcurrent rises the temperature inside the stator winding, and thus the insulating material may catch fire. In thisstudy, the restrained operating condition of the single-phase induction motor was simulated. Further, the degree of theovercurrent and temperature rise in the stator winding was measured. The experimental results, confirmed that theovercurrent was seven times larger than the rated current and the fire commenced at a temperature of approximately 300℃ inside the stator winding.
지홍근(Hong-Keun Ji),박찬용(Chan-Yong Park),길경석(Gyung-Suk Kil),김일권(Il-Kwon Kim),조영진(Young-Jin Cho) 한국철도학회 2008 한국철도학회 학술발표대회논문집 Vol.- No.-
This paper described the design and fabrication of a series arc detection module to monitor electrical insulation in low-voltage system. The module consists of a passive high-pass filter with a low cut-off frequency of 3 kHz to attenuate power frequency voltage by 80 dB and an active band-pass filter with a frequency of 4 kHz to detect series arc signals only. For the application experiment, we simulated series arcing phenomena on various loads such as incandescent lamp controlled by dimmer and inverter fed induction motors by an arc generator specified in UL1699. From the experimental results, we could detect series arc signals without an influence of noises.
지홍근(Hong-Keun Ji),최성국(Sung-Kuk Choi),김선재(Sun-Jae Kim),박성주(Sung-Ju Park),길경석(Gyung-Suk Kil) 한국마린엔지니어링학회 2009 한국마린엔지니어링학회 학술대회 논문집 Vol.2009 No.-
This paper described the application of high brightness Light Emitting Diode (LED) to shipboard lighting system. The LED is good light source especially for shipboard lighting because of its compact structure which makes perfect proof against water, explosion, vibration, and shock. Also, low maintenance cost is expected due to its longer lifetime in comparison with conventional lamps. We considered energy saving and reliability in the application of LED to shipboard lighting. A field survey and a laboratory test results showed that about 30% of energy saving is possible. However, new concept is needed for the design of LED-module and fixture to avoid problems such as heat, vibration, and electromagnetic interference(EMI).
지홍근(Hong-Keun Ji),최성국(Sung-Kuk Choi),정광석(Kwang-Seok Jung),박대원(Dae-Won Park),길경석(Gyung-Suk Kil) 한국철도학회 2009 한국철도학회 학술발표대회논문집 Vol.2009 No.5월
This paper describes a series arc detection algorithm in a low-voltage wiring system. We designed and fabricated an arc detection circuit which consists of a high-pass filter with the low cut-off frequency of 170 ㎑ to attenuate power frequency. The series arcing phenomena was simulated by an arc generator specified in UL1699. In the experiment, various loads such as resistive loads, resistive loads controlled by a dimmer, and vacuum cleaners were used. Whether the signal is arc or noise is discriminated by pulse counts and periodicity of the detected signal.
지홍근(Hong-Keun Ji),박대원(Dae-Won Park),김일권(Il-Kwon Kim),길경석(Gyung-Suk Kil) 한국철도학회 2008 한국철도학회 학술발표대회논문집 Vol.- No.-
This paper describes a series arc detection algorithm in a low-voltage wiring system. We designed and fabricated an arc detection circuit which consists of a high-pass filter with the low cut-off frequency of 3 ㎑ to attenuate power frequency. The series arcing phenomena was simulated by an arc generator specified in UL1699. In the experiment, various loads such as resistive loads, resistive loads controlled by a dimmer, and vacuum cleaners were used. Whether the signal is arc or noise is discriminated by pulse counts and periodicity of the detected signal.
새로운 미백제인 천화분근, 하고초엽, 위령선근의 효능, 효과 및 안정화에 대한 연구
지홍근 ( Hong Guen Ji ),최정식 ( Jung Sik Choi ),이순근 ( Soon Keun Lee ),조용백 ( Yong Baik Cho ),표성수 ( Sung Soo Pyo ),한창균 ( Chang Kyun Han ),김주현 ( Joo Hyon Kim ),정기원 ( Ki Won Joung ),윤세준 ( Se Jun Yun ),신정주 ( Je 대한화장품학회 2004 대한화장품학회지 Vol.30 No.1
최근 기능성 화장품의 대두로 새로운 형태의 미백제들이 많이 출시되고 있다. 본 연구에서는 천화분근, 하고초엽, 위령선근을 이용하여 새로운 미백제를 개발하였다. 그러나 이러한 미백제는 용해성이 좋지 않고 빛, 열, 산소에 의하여 변색 및 함량의 변화를 가져온다. 먼저 천화분근, 하고초엽, 위령선근을 10배수의 50% 에탄올을 넣어 75∼85도에서 6∼8시간 추출한 후 여과, 농축, 건조하였다. 건조된 추출물을 이용하여 티로시나제 효소 활성 억제효과, 마우스의 색소세포를 이용한 B16 멜라닌 생성 억제 효과, brown guinea pig의 동물 피부의 미백효과 결과 다른 비교 샘플에 비하여 매우 우수한 결과가 나왔다. 또한 천화분근, 하고초엽, 위령선근을 안정화시키기 위해서 propylene glycol (PG)/hydrogenated lecithin/middle chain triglycerides (MCT)/glycerin/water를 고압균질화기를 이용하여 30∼50 nm인 리포좀을 만들었다. 이러한 리포좀은 기존의 처리되지 않은 추출물에 비하여 빛과 열에 3∼5배 안정성을 보였다. 이러한 실험을 위하여 particle size analyzer, freeze fracture transmission electron microscopy (FF-TEM), chromameter, HPLC의 분석장비를 사용하였다. Numerous novel ingredients have been introduced for the higher functionality of whitening cosmetics. Through the preliminary research, we have found Trichosanthes kirilowii root, Prunella vulgaris leaf and Clematis chinensis root have high whitening efficacy. But they are insoluble. Moreover the discoloration of and decrease in content take place when they are exposed to light, heat or oxygen. From Trichosanthes kirilowii root, Prunella vulgaris leaf and Clematis chinensis root, efficacious ingredients were ethanol-extracted by heating to 75∼85°C for 6∼8 h. These extracts have the inhibitory activity of tyrosinase and B16 melanin formation, thus enhancing whitening effect. We made liposomes using propylene glycol (PG)/hydrogenated lecithin/middle chain triglycerides (MCT)/glycerin/water and microfuidizer to stabilize extracts. The stability against heat and light was enhanced by 3∼5 times compared with untreated extracts. Particle size analyzer, freeze fracture transmission electron microscopy (FF-TEM), chromameter and HPLC are used for the analysis.
사례 분석을 통한 김치냉장고의 화재 위험성에 관한 연구
박남규,지홍근,송재용,Park, Nam Kyu,Ji, Hong Keun,Song, Jae Yong 한국안전학회 2020 한국안전학회지 Vol.35 No.2
In this paper, we describe fire risk of Kimchi refrigerator. The Kimchi refrigerator has been widely spread and used starting from the first half of 2000 and recently fire accidents caused by the Kimchi refrigerator emerged as social concern. In particular, in products of a specific manufacturer, it is not an environmental factor, but a characteristic that the fire is caused due to a defect of the product itself is shown. These features are judged to be formed by unique defects regardless of external factor by forming electrically arc mark in the relay element. In this paper, we analyzed the cause of the fire occurring in the Kimchi refrigerator and finally confirmed the characteristic that the fire occurred mainly in the relay element due to insufficient capacity of the relay element. Therefore, when a fire occurs in a product of the same maker as the Kimchi refrigerator mentioned in this paper, it is always judged that the inspection of the relay element should be carried out.
Phospholipid 의 Gelation 에 의한 Liposome 형성과 안정성
김인영,지홍근,홍창용,강삼우 ( In Young Kim,Hong Keun Ji,Chang Yong Hong,Sam Woo Kang ) 한국유화학회 1996 한국응용과학기술학회지 Vol.13 No.1
The liposomes have been developed in many drugs and cosmetics fields. The liposomes prepared with main compounds of the intercellular lipids and lecithin. Amphiphile nonionic surfactants used for (PEG) n-sitosterol(n=5), diethanolamine cetylphosthate. The effect of gelation for liposomes have been on swelling reaction which have been mixed phospholipid with polyol-group at the high temperature. There were very good encapsulated properties of the active ingredients whether hydrophilic-group(magnesium ascorbyl phosphate, allantoin, sodium hyaluronate) and hydrophobic-group(vitamin-E acetate, vitamin-A palmitate). Optimum condition of liposomes were passed five times in the microfluidizer(700bar), wetting reaction temperature was at 95±5℃ for a hours. Particle size distribution of the vesicles should be within range 50-560nm(mean 200nm). The stability of liposomes for the course of time was stabilized for six months at 45℃. Application of the cosmetic was prepared moisturizing cream with liposomes of the phospholipid base.