• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.178-178
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• 1999

Low temperature Si epitaxy can provide flexibility for a device designer to tailor or optimize the device performance. It is better method for controlling the doping thickness, concentration and profile than ion implantation and diffusion. But there is a limited growth thickness in this method. At a given temperature, the film grows epitaxially for a certain limiting thickness(hepi) and becomes amorphous. The transition from crystalline Si to amorphous Si is abrupt. In this study, Si film was deposited by ion beam sputter deposition on Si (0001) above a limiting thickness and measure the strain in the interface between crystalline Si and amorphous Si. The strain was compressive and the maximum value was about 2%.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.212-213
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• 2008

This paper describes the analysis of the device characteristics of the NPT type 1200V Insulated gate Bipolar Transistor. In case of NPT type IGBT devices, optimized n-epi layer thickness and concentration is important to obtain low on-state voltage and breakdown voltage characteristics. In this paper, we analyzed on-state and off-state characteristics of NPT type IGBT. Breakdown voltage of designed IGBT was higher than 1200V when we optimized Field Limiting Ring structures. And also, on-state voltage characteristics was shown less then 2.5V at 25A of drain current.

• 한국해양공학회지
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• 제13권1호통권31호
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• pp.121-129
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• 1999

Double-diffusive convection with verical temperature and concentration gradients in thermally stratified fluids has been investigated experimentally using an electrochemical technique. Cupric sulfuric-sulffuric acid solution confined between two horizontal copper electrodes was used. The change of thermal and solutal buoyance has no influence on the range of voltage for the limiting current. Due to Soret effect, the onset time of natural convection is delayed as the stabilizing thermal buoyancy decreases. Also it is found that the shrinkage of the unstabilizing solutal buoyancy makes the onset of natural convection retard. Multi-layered convective phenomena do not appear because cupric sulfate-sulfuric acid solution is thermally stratified, and heat diffuses faster than cupric sulfate solfate solution.

• 한국환경과학회지
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• 제4권5호
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• pp.469-479
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• 1995

The increase of population and industrial activities had brought into eutrophication in the Nakdong river. A remarkable acceleration of eutrophication brought about serious problems for water supply. Therefore, for the purpose of conservation of water quality in the Nakdong river it is necessary to control nutrients. MBOD method was use to evaluate algal growth limiting factor and algal growth potential in the Nakdong river from June to August 1994. The modified biochemical oxygen demand(MBOD) depends on the amount of available inorganic nutrient and organic substrate during 5 day incubation in the dark at 2$0^{\circ}C$. The MBOD assay depends on inorganic nutrients such as P and N as well as reduced carbon and called the MBOD, the MBOD-P, and the MBOD-N, respectively. The results of bioassay by MBOD(Modified BOD) method showed that the MBOD, MBOD-P and MBOD-N value were found to be in the ranges of 3.8~96.0 mg$O_2$/l, 5.6~94.0 mg$O_2$/l and 42.0~220 mg$O_2$/l, respectively. And the the bioassay value was found to be the highest in Koryong area and the lowest in Waekwan area throughout the Nakdong river. The variations of MBOD-P and MBOD-N value showed similar tendencies to the variations of phosphorus and nitrogen value, respectively. By MBOD method, the relationships of MBOD, MBOD-P and MBOD-N value were MBOD ≒ MBOD-P 《 MBOD-N. The MBOD value was nearly equal to the MBOD-P value, and the MBOD-N value was 3 to 20 times more than the MBOD-P value, approximately. Therefore, in the Nakdong river, phosphorus was the limiting factor for algal growth during summer season. The algal growth potential as the concentration of chlorophyll-a in the summer was maximum 5 times more than standing crop as it.

• Current Optics and Photonics
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• 제7권6호
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• pp.721-731
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• 2023

This paper studies various roughness parameters, besides waviness, texture, and nonlinear parameters of Bismarck brown Y (BBY)-doped Poly(methyl methacrylate) (PMMA) films based on the computed values of optical limiting (OL) threshold power and nonlinear refractive index. The films' morphology, grain size, and absorption spectra were investigated using atomic force microscopy in conjunction with ultraviolet-visible (UV-Vis) spectrophotometer. The particle size of the films ranged between 4.11-4.51 mm and polymer films showed good homogeneity and medium roughness, ranging from 1.11-4.58 mm. A polymer film's third-order nonlinear optical features were carried out using the Z-scan methodology. The measurements were obtained by a continuous wave produced from a solid-state laser with a 532 nm wavelength. According to the results, BBY has a nonlinear refractive index of 10^-6 cm²/W that is significantly negative and nonlinear. The optical limiting thresholds are roughly 10.29, 13.52, and 18.71 mW, respectively. The shift of nonlinear optical features with the film's concentration was found throughout the experiment Additionally, we found that the polymer samples have outstanding capabilities for restricting the amount of optical power that may be transmitted through them. We propose that these films have the potential to be used in a wide variety of optoelectronic applications, including optical photodetectors and optical switching.

• KSBB Journal
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• 제4권3호
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• pp.259-265
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• 1989

당근세포의 현탁배양에서 배지중 제한영양소인 인산염과 글루코우즈 농도에 대한 당근세포 배양특성에 관한 실험으로부터 다음의 결론을 얻었다. 1) 배지중의 글로코우즈와 인산염을 제한영양소로 하였을 때, 현탁배양 중의 글루코우즈의 농도 1.49g/l - 3.01g /l, 인산염의 농도 0.08mM - 1.06mM의 범위에서 세포성장 정체기에 도달하는 시간은 13.2hr-66.4hr였고 제한영양소의 전환율은 초기 글루코우즈와 인산염의 농도의 5~30% 범위내에 분포되었다. 2) 제한 영양소의 저농도범위에서의 농도변화에 따른 세포의 비성장속도, $\mu$는 $0.15day^{-1}$와 $0.3day^{-1}$사이의 값으로 일정한 경향을 보이지 않았는데, 이것은 제한요소가 저농도로 존재할 때 세포의 비성장속도에 미치는 영향이 적음을 알 수 있다. 3) 제한 영양소의 소모량과 세포증가량 사이에는 선형적 관계를 나타내며, 제한 영양소 글루코우즈에 대한 세포수율($Y_{x/sG}$)은 인산염 0.32mM, 글루코우즈 2.67g/l에서 $98.71{\times}10^{10}개\;/\;g로$ 최대값을 나타내었다. 4) 제한 영양소의 비($s_G/s_P$)에 대한 비성장속도, $\mu$ 및 세포수율($Y_{x/s_G}$는 두 농도의 비($s_G/s_P$)가 20mM/mM-120mM/mM 사이에서 임의적으로 분포하였다.

• 한국응용과학기술학회지
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• 제3권1호
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• pp.23-31
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• 1986

Several authors reported that vegetable proteins cause to decrease serum cholesterol and reported the effect of limiting amino acid balance in dietary protein on the blood component. This study was designed to observe growth rate and blood component in 1% cholesterol-fed male rats intake pure isolated soy proteins and methionine for 4 weeks. The diets were supplemented with either 20% casein or isolated soy protein as dietary protein sources and methionine as limiting amino acid of isolated soy protein and casein protein. The results were as follows; 1) The body weight gain was the greatest in casein groups. 2) Serum total cholesterol concentration was significantly increased by casein groups and slightly decreased by isolated soy protein groups. 3) Serum HDL-cholesterol concentration was significantly increased by isolated soy protein groups than control group. 4) Serum total lipid and triglyceride concentrations were significantly decreased by isolated soy protein groups than control group. 5) Serum glucose concentration was significantly increased by isolated soy protein plus 0.8% methionine than control group. 6) Serum total protein and albumin concentrations were significantly increased by all experimental diets groups than control group. Especially, casein groups were the most increased in all experimental diets groups.

• 한국미생물·생명공학회지
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• 제13권3호
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• pp.257-263
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• 1985

Rhodopseudomonas sp. KCTC 1437은 글루타민산이 질소원으로 존재할 때, 포도당으로부터 질소고 정효소 (nitrogenase)에 의해 효율적으로 수소를 생성하였다. in vivo에서 질소고정 효소의 활성도를 조사해 본 결과, 암모니아 이온의 제한 농도에서 키운 균체가 다른 질소원에서 키운 균체보다 더 큰 정도로 수소를 글루타민산 존재하에서 포도당으로부터 생성하였다. 이 균주는 또한 수소 생성의 억제물질 및 조건으로 알려져 있는 암모니아 이온의 높은 농도와 암조건에서 높은 정도로 수소를 생성했는데 이것은 수소효소 (hydrogenase)의 일종인 포르믹산 수소분해효소 (formic hydrogenlyase)에 의한 것이라 고려된다.

• 해양환경안전학회지
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• 제23권7호
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• pp.885-892
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• 2017

2017년 추계에 남해 전선역을 파악하고, 알칼리 인산분해 효소(Alkaline Phosphatase; APase) 활성을 이용하여 제한 영양염과 제한 영양염의 시간적인 변화를 평가하였다. 전선역이 형성된 인근해역의 경우, 용존무기인(dissolved inorganic phosphorus; DIP)의 농도와 용존무기질소(dissolved inorganic nitrogen; DIN): DIP 비가 각각 $0.2{\mu}M$ 이하와 최대 23.2로, DIP가 제한된 환경임에도 불구하고 Chlorophyll a(Chl.-a)가 $0.2{\mu}g/L$로 높은 생물생산력을 보였다. APase와 DIP는 중요한 역의 상관관계(r = -0.81; P<0.001)를 보여, DIP가 제한되어진 해역임을 알 수 있었으며, APase와 Chl-a 관계는 APase의 60 %가 식물플랑크톤, 40 %가 박테리아 기원인 것으로 평가되었다. 용존태 APase와 입자태 APase의 분포로부터 전선역은 장기간 DIP가 제한된 해역이며, 그 외의 해역은 최근에 DIP 제한이 해소된 것으로 판단되었다. 따라서 전선역에서 APase와 같이 가수분해효소의 측정은 제한 영양염의 시공간적인 변화 특성을 평가할 수 있으며, 전선역에서 생지화학 순환의 이해를 높일 수 있을 것으로 생각된다.

• 한국화재소방학회논문지
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• 제15권4호
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• pp.34-40
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• 2001

HPMC의 자연발화는 일정한 주위온도에서 자연발화의 연구와 Godbret-Greenwald가 고안한 전기로에서 운상상태의 최소발화온도를 구하였으며, 시료를 용기에 충전했을 경우 용기의 크기가 클수록 발화한계 온도는 낮아졌으며 겉보기활성화에너지는 Frank-Kamenetskii의 열발화이론으로부터 계산하였고, 운상상태의 발화온도는 21%의 산소농도하에서 최소발화온도를 구하였으며, 산소농도 변화의 실험결과 산소농도 10%에서 발화되지 않았으며 한계산소농도를 구할 수 있었다.