• 한국정보과학회논문지:정보통신
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• 제32권6호
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• pp.723-731
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• 2005

오늘날 인프라 무선 랜은 많은 사용자들이 사용하는 중요한 인터넷 접속 기술이다. 지금까지 무선 랜에 관한 연구들은 물리 계층의 채널 다양성으로 인하여 발생하는 모델링 부정확성에 대해 충분히 고려하지 않고, MAC 프로토콜의 향상 및 분석 그리고 시뮬레이션을 통한 성능 평가에만 초점을 맞추어 왔다. 본 논문에서는 계층 상호 간의 의존성의 중요성에 주목하는 새로운 시각으로 IEEE 802.11 무선 랜의 특성을 고찰한다. 실제 무선 랜 시스템 상에서 실험을 수행하여 물리 계층에서 발생하는 불평등성을 관찰하였다. 그리고, 그것이 노드들 간의 혼잡 수준을 떨어뜨리는 역할을 하여 경쟁 기반의 MAC 처리율이 혼잡 상태에서도 서서히 감소하는 것을 보인다. 반면에 노드들 간의 공평성과 노드 처리율의 안정성은 시스템 입력 로드가 특정 수준을 넘으면 크게 저하되는 것을 보인다. 이와 같은 결과를 통하여, 처리율을 높이기 위해 링크 계층에서 제어를 할 필요성은 적은 반면에, 공평한 자원 분배나 서비스의 품질을 보장하기 위해서는 트래픽 제어가 필요하다는 것을 알 수 있다. 시스템의 성능 평가를 위하여 시뮬레이션과 실험을 병행하였다.

• 한국안전학회지
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• 제21권2호
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• pp.29-34
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• 2006

It is revealed that these are correlated with the height of chamber deciding the turbulence extent. In the first experiment, It was examined about the effects of different multiple obstacles such as circular, triangular and square things with the rig that the dimension of original experimental rig was $700{\times}700{\times}200mm{\wedge}3$. Then the heights of chamber were increased from 200 to 1000mm. The dimensions of each obstacle were $70{\times}700{\times}{\wedge}2$ and rectangular vent area were $210{\times}700{\times}{\wedge}2$. In the second one, we performed to see the effects of locations of different multiple obstacles in 200, 500 and 800mm height from the bottom. The results are : The multiple triangular obstacles caused the highest overpressure while the lowest one was the multiple circle bars. Then, the triangular bars caused the highest flame acceleration while the circular obstacles was lowest too. The results showed that the critical height was 800mm due to the formation of turbulence. And the lesser $Av/V^{2/3}$ were small, the more pressure and pressure acceleration rate were increased.

• 한국환경농학회지
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• 제30권2호
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• pp.223-228
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• 2011

BACKGROUND: Rhizosphere bacteria may improve plant growth and productivity both by supply nutrients and hormonal stimulation. Although many experiments have shown improvements in plant growth with inoculation of bacterial cultures to the rhizosphere, the main obstacle in the applications of plant growth promoting rhizobacteria in a large scale is the inconsistency of the results. We tested the growth promoting effects of Azospirillum and Methylobacterium strains on red pepper plant. METHODS AND RESULTS: Red pepper seedlings were grown for 25 days in a growth media inoculated with A. brasilense CW903 or M. oryzae CBMB20. The seedlings were transplanted and grown for 45 days in pots with soil in a greenhouse, at half the recommended level of fertilizer. Bacterial culture, $4.0{\times}10^9$ for A. brasilense CW903 and $5.8{\times}10^8$ CFU for M. oryzae CBMB20, was applied in root zone soil periodically every 10 days during the experiment. Inoculation of M. oryzae CBMB20 significantly increased the red pepper plant growth in terms of leaf number, height and mass of shoot, or root mass compared to uninoculated control plants. Although beneficial effects of A. brasilense on plant growth of many crops were observed, the growthpromoting effect of A. brasilense CW903 on red pepper plant was not found in this study. CONCLUSION(s): The factors responsible for the irregularities in plant growth promoting of rhizobacteria are difficult to elucidate. Extensive inoculation experiments in the greenhouse and in the field should enable us to define the factors critical to obtain successful application of plant growth promoting rhizobacteria.

• 한국식품과학회지
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• 제19권6호
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• pp.463-470
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• 1987

건조 식품의 적절한 포장 기법을 확립하고 포장된 제품의 품질 변화를 신속하게 예측할 수 있는 방법을 개발하고자 건조 김을 모델 식품으로 하여 저장 온 습도 조건 및 포장재별로 수분활성도 및 품질 지표 물질로서 chlorophyll a의 변화를 simulation하고 shelf-life를 예측하였다. 수분활성도와 chlorophyll a의 반응 상수 사이의 수학적인 변화 모델을 $10^{\circ}C,\;25^{\circ}C$ 및 $40^{\circ}C$에서 설정하였다. 수분 함량. 저장 온 습도 및 포장재와 같은 저장 조건의 영향을 동시에 고려하여 제품의 수분활성도 및 품질 지표 물질인 chlorophyll a의 변화를 예측할 수 있는 컴퓨터 simulation 방법이 개발되었다. simulation에 의해 예측된 품질 변화는 실측치와 잘 일치하였다. 수분활성도가 증가함에 따라 기호도 및 chlorophyll a는 감소하였으며, 기호도와 chlorophyll a와의 상관관계도 매우 높아 상관계수는 0.991이었다. 관능검사에 의해 측정된 저장 임계 수분활성도는 약 0.55이었다. 여러 저장 조건에서 플라스틱 필름 포장된 건조 김의 shelf-life를 예측할 수 있었다.

• Transactions on Electrical and Electronic Materials
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• 제6권6호
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• pp.276-279
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• 2005

Influences of sustain pulse-width on electrical characteristics and luminous efficiency are experimentally investigated for surface discharge of AC-PDP. A square pulse with variable duty ratio and fixed rising time of 300 ns has been used in the experiment. It is found that the memory coefficient is significantly increased at the critical pulse-width. And the wall charges and wall voltages as well as capacitances are experimentally measured by Q- V analysis method along with the voltage margin relation, in terms of the sustain pulse-width in the range of $1{\mu}s$ to $5{\mu}s$ under driving frequency of 10 kHz to 180 kHz. And the luminous efficiency is also experimentally investigated in above range of sustain pulse-width with driving frequency of 10 kHz to 180 kHz. It is noted that the luminous efficiency for 10 kHz and 180 kHz are 1.29 1m/W and 0.68 1m/W respectively, since the power consumption for 10 kHz is much less than that for 180 kHz. It has been concluded that the optimal sustain pulse-width is in the range of $2.5 {\~}4.5{\mu}s$ under driving frequency range of 10 kHz and 60 kHz, and in the range of $1.5 {\~} 2.5{\mu}s$ under driving frequency range of 120 kHz and 180 kHz based on observation of memory coefficient, and wall voltage as well as luminous efficiency.

• 대한조선학회 특별논문집
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• 대한조선학회 2008년도 특별논문집
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• pp.16-28
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• 2008

Recent growth in LNG market has led dramatic increase in new buildings of LNG carriers and several large LNG carriers are now being constructed by shipbuilders in Korea. Large size LNG carriers has brought keen concerns on the issue regarding safety of cargo containment systems and sloshing impact load which is the critical source of loads on the membrane type containment systems. Up to the present, the best way to properly assess sloshing impact pressures on surrounding walls is a model testing for wide-ranged excitation conditions. These impact pressures obtained from model tests sometimes need to be interpreted to full-scale values and in the near future this necessity will be strengthened for more rigorous and direct safety assessment of LNG cargo containment system. In this paper, a basic experimental study is carried out with two different sized, 2D identically shaped model tanks excited in simple translational motions. Relationships between pressures of different sized model tanks are investigated Model tanks are filled with fresh water and equipped with same sized pressure sensors.

• 약학회지
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• 제45권1호
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• pp.116-124
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• 2001

Nitric oxide is a labile, gaseous, broad spectrum second messenger that used in various tissues and cells. If it is induced by endogenously and exogenously in the neuronal cells, it is able to mediate analgesia or hyperalgesia at the periphery and in the spinal level respectively. This dual role of nitric oxide in the sensory system is very intriguing but has not been fully understood yet. In this experiment, acetylcholine (300 $\mu$g/paw), sodium nitroprusside (600 $\mu$g/paw), and L-arginine (300 $\mu$g/paw) represented antinociceptive effect to noxious topical stimulus, but pronociceptive responses followed by spinally application (20$\mu$g/5$\mu$l, 10$\mu$g/3$\mu$l, 500$\mu$g/5$\mu$l respectively). Calcium ion is critical element which activates nitric oxide synthase, therefore verapamil (300 $\mu$g/paw) and NOS inhibitor (20 mg/kg, L-NAME or L-NOArg) are injected into right hind paw (i.pl.). When verapamil is combined with NOS inhibitors analgesic effects through NO-cGMP pathway are inhibited as compared with ACh alone. Diluted formalin (2.5%), when injected into rats'hind paw (0.05 ml), elicited a biphasic algesic responses and nitric oxide had an analgesic effect on both $A\delta$ and C sensory nerve fibers which manipulate the phases respective1y. Nitric oxides, which produced from constitutive nitric oxide synthase, activated cyclooxygenase-type I and then prostaglandins are produced from them. So, indomethacin and ibuprofen, inhibitors of COX$_1$enzyme, when pretreated intraperitoneally (100 mg/kg) could reduce the hyperalgesic state. From these results, it is possible to imagine that the intrathecally administered NO donors expressed hyperalgesia through both long-term potentiation mechanism and arachidonic acid-prostaglandin cascade.

• 한국전산구조공학회논문집
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• 제20권4호
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• pp.407-416
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• 2007

가스터빈에서 연료 분무 노즐은 연소 특성에 영향을 미치는 중요한 부품이다. 스월 분무 장치를 설계하기 위하여 유량과 분무액적 평균 직경을 설계변수로 정하고 연료 분무 노즐의 최적화를 수행하였다. 설계변수는 이중 노즐의 실험값들을 비교하여 중요한 영향을 미치는 변수로 선정하였다. 민감도는 유량과 분무액적 평균 직경의 변화에 따른 값을 사용하였다. 이중 오리피스형 스월 분무장치의 형상 최적설계를 통하여 유량의 미립화를 높이도록 연구하였다. 최적설계를 위하여 실험 계획법을 이용하였으며, 영향을 적게 미치는 설계변수들은 설계대상에서 제외하였다. 분무 노즐의 분무액적 평균 직경을 사용한 결과는 Jasuja의 액적 평균 이론을 이용하여 도출된 결과와 유사함을 알 수 있었다. 연구 결과는 이중 오리피스형스월 분무장치와 이와 비슷한 종류의 노즐 최적화를 위한 특성을 파악하고 최적의 유량과 허용 공차를 제시하였다.

• 대한환경공학회지
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• 제35권3호
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• pp.200-205
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• 2013

전처리 공정은 막의 오염 정도를 제어할 수 있는 유일한 방법이다. 막의 오염 현상은 피할 수 없는 중요한 문제이며 RO 공급수로 적합한 전처리 공정의 선택이 중요하다. 본 연구는 pH, 해수의 탁도, 수온, 응집제 주입량 그리고 SDI 측정 막재질과 같은 SDI 값에 영향을 미치는 인자들을 평가 하기위해 수행되었다. 그 결과 해수의 탁도는 여과수의 SDI 값에 약간의 영향을 미친것으로 조사되었다. 0.45 um 공극 크기를 가지는 SDI 측정 막은 소수성 막 보다 동일한 재질의 친수성 막을 이용하는 것이 분석 결과의 신뢰성과 재현성을 확보할 수 있었다. pH 7.0 이하의 조건에서 pH가 감소할수록 SDI 값은 증가한 것으로 나타났다. 그리고 수온은 SDI 값은 큰 영향을 미친것으로 조사되었다.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.62-62
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• 2003

The native form of serpin (serine protease inhibitor) is kinetically trapped in metastable state. Metastability in these proteins is critical to their biological function. Serpins inhibit target proteases by forming a stable covalent complex in which the cleaved reactive site loop of the serpin is inserted into $\beta$-sheet A of the serpin with concomitant translocation of the protease to the opposite of the initial binding site. Despite recent determination of the crystal structures of a Michaelis protease-serpin complex as well as a stable covalent complex, details on the kinetic mechanism remain unsolved. In this study we constructed several $\alpha$$_1$-antitrypsin variants and examined their kinetic mechanism of loop translocation and formation of protease-serpin complex by stopped-flow experiments of fluorescence resonance energy transfer as well as quenched-flow experiment. We report here the relationship of serpin's conformational switch mechanism with Inhibitory activity. There is little direct correlation between loop insertion rate and inhibitory activity. Rather, disrupting a salt bridge between R196 and E354 accelerates loop translocation even though it impairs the inhibitory activity. Moreover, the serpin's reactive site loop is translocated, at least partially, prior to loop cleavage.