• 제목/요약/키워드: Releasing Rate

검색결과 246건 처리시간 0.024초

불산수용액 누출사고에 대한 초기대응 단계별 영향 (Effects of Initial Responses in Steps for the Release Accidents of Hydrofluoric Acid)

  • 최재식;최재우;심주용;이무철
    • Korean Chemical Engineering Research
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    • 제59권1호
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    • pp.68-76
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    • 2021
  • 화학 및 석유화학 공장과 같은 공정산업에서 위험물질이 누출할 때 초기대응의 중요성은 항상 강조되어 왔다. 그러나 이러한 화학물질의 누출동안 단계별 초기대응에 따른 피해예측에 대한 정량적 분석에 대한 연구는 그 동안 미흡하였다. 이에 본 연구에서는 불산 누출사고 동안에 초기대응의 영향을 조사하고자 하였고, 이를 위해 불산농도 범위에 따른 피해예측 영향거리를 산정할 수 있는 간이식을 우선 도출하였다. 그리고 시스템 다이내믹스 기법을 활용하여 초기 대응 단계의 인과지도를 작성하였고, 인과지도에 도출한 간이식을 적용하여 다양한 초기대응 시나리오에 따른 피해예측 영향거리를 분석하였다. 연구결과, 최대피해영향거리와 비교할 때'누출발견 후 초기조치 시작시간'인 경우 최대 약 87%, '누출부위 차단조치'는 약 59%, '전문진압팀 도착시간'이후 조치는 약 50% 감소율을 보였다. 이 연구결과는 불산 취급 사업장에서의 초기대응 지침의 기초자료로 활용하는데 도움이 될 것으로 판단된다.

회분식 광펄스 처리에 의한 병원성 대장균의 비가열 살균 (Nonthermal Sterilization of Pathogenic Escherichia coli by Intense Pulsed Light Using a Batch System)

  • 김애진;신정규
    • 한국식품과학회지
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    • 제47권1호
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    • pp.81-86
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    • 2015
  • 광펄스 기술의 주요 공정 변수인 빛의 세기, 펄스 수, 광원과 시료사이의 거리에 따른 병원성 대장균의 사멸효과, 형태학적 변화와 세포의 손상 및 회복 여부를 알아보았다. 1,000 V, 5 pps, 7.9 cm에서 병원성 대장균을 광펄스 처리하였을 경우 처리시간이 증가함에 따라 사멸정도가 증가하였으며, 120초 처리하였을 때 약 7.1 log CFU/mL 감소하였고, 사멸속도는 $0.07s^{-1}$이었다. 같은 빛의 세기에서는 펄스수가 증가할수록 사멸정도가 증가하였으며, 램프와 시료의 거리가 가까울수록 사멸효과가 높았다. 광펄스 처리에 의한 미생물의 사멸은 세포막의 파괴에 의한 것으로 처리 시간이 증가함에 따라 세포내 물질의 외부 유출이 증가하며, 사멸되지 않은 세포라도 손상을 입어 정상적인 생육을 하지 못하는 것으로 보아 사멸이 물리적 손상 이외에의 생물학적 손상이 있는 것으로 판단된다. 세포의 물리적 손상 여부를 전자 현미경으로 살펴본 결과 광펄스 처리를 받은 세포는 세포막에 손상을 입어 세포내 물질의 유출이 일어난 것을 알 수 있었다.

일부 여대생의 흡연실태와 그 관련요인 분석 (A Survey on Smoking Status and Its Related Factors for Female Students of A Women's University in Seoul)

  • 곽정옥
    • 보건교육건강증진학회지
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    • 제12권2호
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    • pp.120-138
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    • 1995
  • In order to find smoking status and its related factors for female students, a survey was conducted for 1,045 female students of a women's university in Seoul from 22nd of May to 18th of June, 1995. The results were as follows: 1. Of the 1,045 respondents, 7.4% of them were current smokers and 20.6% of them were ex-smokers. The rate of smoking by the major field of study was 18.5% in art and physical education, 10.6% in liberal art and social science, 1.9% in natural science, and 1.2% in medical science. The rate of smoking by the grade was 4.1% in the freshman, 5.9% in the sophomore, 10.9% in the junior, and 10.0% in the senior grade. 2. 7.2% of respondents experienced first smoking at junior high school, 16.8% at senior high school, 4.1% after high school, and 69.2% at college. 3. The major motivation to start smoking was 'curiosity'(57.9%), 'releasing stress'(21.6%), and 'temptation from friend or senior'(12.0%). 4. The first smoking place was 'entertainment place'(49.6%), 'own room'(20.5%), and 'school '(11.3%). And the first smoking companion was 'friend'(62.3%), 'alone'(19.9%), and 'senior or junior'(5.1%). 5. The average quantity of a daily smoking was 6.16±5.29 cigarettes in current smokers and 31.2% of them had experience to quit smoking at least one or more time. 6. Most of the reasons to quit smoking in ex-smoker were due to 'bad taste '(60.5%), 'health concern'(27.4%) and 'religion'(2.3%). 7. Current smoker and ex-smoker had more positive attitude for the female smoking than nonsmoker. And 76.7% of nonsmokers answered that they would not smoke in the future. 8. Most correspondents(89.8% of nonsmoker, 83.7% of ex-smoker, 80.5% of current smoker) strongly supported the antismoking movement. 9. The major information source in smoking were from 'radio, TV'(51.0%), 'newspaper, magazine'(38.8%) and 'school'(7.7%). 10. The multiple logistic regression analysis showed that the related factors for smoking status were satisfaction of home life, coffee intake, alcohol drinking, sister's smoking, girl friend's smoking, and knowledge about smoking.

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Evaluation of Nitrogen Fixation between Supernodulating Soybean Mutants and their Wild-Types Using $^{15}N$ in Field Conditions

  • Youn, Jong-Tag;Van, Kyu-Jung;Ryu, Yong-Hwan;Shimada, Shinji;Lee, Choon-Ki;Kim, Sun-Lim;Seo, Sea-Jung;Lee, Suk-Ha
    • Journal of Crop Science and Biotechnology
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    • 제11권1호
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    • pp.31-38
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    • 2008
  • Improvement of $N_2$ fixation by symbiotic rhizobia is considered an effective means for enhancing its productivity without high input of nitrogen(N) fertilizer. Several methods to improve $N_2$ fixation have been proposed including the use of supernodulating mutants. The objective of this research was to identify the varietal difference in N and $N_2$-fixation ability among the soybean supernodulating mutants, SS2-2 and Sakukei 4, with different nodulation abilities using $^{15}N$ in field conditions in both Korea and Japan. The dry weight(DW) was higher in wild-type soybeans. The distribution rate of DW in each plant part was high in seeds of supernoduating and wild-type soybeans but high in stems and leaves of non-nodulating mutants. Although the supernodulating mutants had a low DW rate at maturity, they showed a similar $N_2$ fixation ability compared with wild-type. Supernodulating mutant plants mainly obtained N from $N_2$ fixation, while soil N was the main resource for obtaining N in non-nodulating mutants. The percentage of N derived from atmospheric dinitrogen(Ndfa) was higher in supernodulating mutants than in wild-type and relatively high in seeds between plant parts at maturity. In particular, supernodulating mutants showed higher N content in roots than those of wild-type and non-nodulating mutants. It was considered that supernodulating mutants have the advantage of saving nitrate in soil and being beneficial for N absorption of subsequent crops due to their conserving more N in the field and releasing considerable amounts of N from roots and leaves fallen to the soil.

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황련해독탕(黃連解毒湯)과 그 주성분인 황련(黃連) 및 황련(黃連)의 주성분인 berberine이 니코틴 중독 흰쥐에 미치는 영향 (The Effect of Hwangryunhaedok-tang and its Major Component Coptidis Rhizoma, Berberine on Nicotine Addiction in Rats)

  • 홍의재;민상연;김장현
    • 대한한의학회지
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    • 제29권4호
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    • pp.55-67
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    • 2008
  • Objectives: The purpose of this study was to investigate the effect of Hwangryunhaedok-tang, its major component Coptidis Rhizoma, and the major component of Coptidis Rhizoma, berberine, on the expression of behavioral sensitization induced by the repeated administration of nicotine. Methods: Experimental ratswere divided into 3 groups and each group treated with saline, nicotine, and Hwangryunhaedok-tang. Experiments were performed on 4 further groups, each group treated with saline, nicotine, Coptidis Rhizoma, and berberine. To obtain rats addicted todrugs, nicotine was injected repeatedly. After 3 days of withdrawal phase, on the 11th day, rats were re-exposed to nicotine and thus able to induce the expression of the activity sensitization phenomenon successfully. To examine the change of c-Fos in the brain of experimental rats with the nicotine-induced activity sensitization, their neurological activation rate was assessed by c-Fos staining with Fos-like immunihistochemistry of the dopamine releasing area, the striatum and the nucleus accumbens. Results: The result demonstrate that Hwangryunhaedok-tang, its major component Coptidis Rhizoma and berberine,the major component of Coptidis Rhizoma, significantly reduced the walking activity rate in the drug addict models induced by nicotine administration, and Coptidis Rhizoma and its major component berberine reduce the marker of the neurological activation c-Fos, and thus revealed an effect of suppressing drug addiction. Conclusions: These results suggest the possibility of Hwangryunhaedok-tang, its major component Coptidis Rhizoma and the major component of Coptidis Rhizoma, berberine,as therapeutic for nicotine addiction.

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Dynamic Droop-based Inertial Control of a Wind Power Plant

  • Hwang, Min;Chun, Yeong-Han;Park, Jung-Wook;Kang, Yong Cheol
    • Journal of Electrical Engineering and Technology
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    • 제10권3호
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    • pp.1363-1369
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    • 2015
  • The frequency of a power system should be maintained within the allowed limits for stable operation. When a disturbance such as generator tripping occurs in a power system, the frequency is recovered to the nominal value through the inertial, primary, and secondary responses of the operating synchronous generators (SGs). However, for a power system with high wind penetration, the system inertia will decrease significantly because wind generators (WGs) are operating decoupled from the power system. This paper proposes a dynamic droop-based inertial control for a WG. The proposed inertial control determines the dynamic droop depending on the rate of change of frequency (ROCOF). At the initial period of a disturbance, where the ROCOF is large, the droop is set to be small to release a large amount of the kinetic energy (KE) and thus the frequency nadir can be increased significantly. However, as times goes on, the ROCOF will decrease and thus the droop is set to be large to prevent over-deceleration of the rotor speed of a WG. The performance of the proposed inertial control was investigated in a model system, which includes a 200 MW wind power plant (WPP) and five SGs using an EMTP-RV simulator. The test results indicate that the proposed scheme improves the frequency nadir significantly by releasing a large amount of the KE during the initial period of a disturbance.

일방향 도로터널내 화재 발생시 역류를 막는 환기속도결정에 관한 축소모형실험 (The Reduced Model Test for the Determination of Ventilation Velocity to Prevent Backflow in Uni-directional Road Tunnel during a Fire Disaster)

  • 유영일;이희근
    • 터널과지하공간
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    • 제8권2호
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    • pp.107-117
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    • 1998
  • In the case of a fire disaster in a uni-directional road tunnel, it is important to determine the critical ventilation velocity to prevent the backflow travelling toward the tunnel exit where vehicles are stopped. The critical ventilation velocity is horizontal velocity to prevent hot smoke from moving toward the tunnel exit. According to Froude modelling, the model tunnel whcih was 300mm in diameter and 21 m in length was made of acryl tubes. Inner section of acryl tubes was clothed with polycarbonate. 1/20 scaled model vehicles were installed to simulate the situation that vehicles are stopped in the tunnel exit. Methanol in a pool type burner was burned in the middle of tunnel to simulate a fire hazard. In this study, the basis of determining the critical ventilation velocity is the ventilation flow rate that is able to maintain the allowable CO concentration in the tunnel section. We assumed that the allowable CO concentration was backflow dispersion index. Futhermore, We intended to find out CO distribution and temperature distribution according as we changed ventilation velocity. The results of this study were that no backflow happened when ventilation velocity was 0.52 m/s in the case of 5.75 kW. If we adapt these results of a fire disaster releasing 10MW heat capacity in real tunnel which is 400m in length, no backflow happens when ventilation velocity is 2.31m/s. After we figured out dimensionless heat release rate and dimensionless ventilation velocity of model test and those of real test to verify experimental correctness, we tried to find out correlation between experimental results of model tunnel and those of real tunnel.

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메탄발효 효율향상을 위한 하.폐수 슬러지의 전처리 기술 (Pretreatment of Waste-activated Sludge for Enhancement of Methane Production)

  • 남궁규철;전체옥
    • 한국미생물·생명공학회지
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    • 제38권4호
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    • pp.362-372
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    • 2010
  • 다양한 하 폐수 처리공정 중 혐기성 소화공정은 이산화탄소 배출을 감소시키고 생성되는 메탄을 에너지로서 사용할 수 있는 장점을 가지고 있다. 본 논문에서는 이러한 혐기성 소화공정의 문제점과 보완점에 대해 살펴보았다. 가수분해과정은 혐기성 소화과정 중 율속단계에 해당하여 소화공정과정을 촉진시키고 바이오가스의 생산을 증가시키기 위하여 다양한 전처리 방법이 개발되어왔다. 현재 혐기성 소화공정을 위한 전처리 방법 중 열처리 방법, 초음파 처리, 기계적 처리방법, 화학적 처리방법 등이 상업적으로 이용되고 있으며, 이들 공정은 슬러지 플록 또는 세포의 파괴를 통해 세포분획물이 생물학적으로 분해될 수 있는 형태로 전환시키는 것을 목적으로 한다. 이러한 과정들 모두는 특정 상황에 따른 장점과 단점을 모두 지니고 있으므로 각 공정과정에 대한 이해와 이를 통한 적용을 통해 특정 슬러지에 적합한 최적의 전처리 공정을 도출해 낼 필요가 있다. 또한 혐기성 소화공정의 효율증대와 경제성 확대를 위한 혐기성 소화공정 개발이 필요하다고 할 수 있다.

비의 양이 지수분포를 따르는 경우 무한 댐의 최적 방출정책 연구 (An optimal policy for an infinite dam with exponential inputs of water)

  • 김명화;백지선;최승경;이의용
    • Journal of the Korean Data and Information Science Society
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    • 제22권6호
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    • pp.1089-1096
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    • 2011
  • 본 논문에서는 댐으로 물이 복합 포아송 과정을 따라 유입되고, 댐 수위가 적정수준 ${\lambda}$를 넘어서게 되면 방출률 M으로 물을 방출하는 무한 댐 모형이 고려된다. 한번 내리는 비의 양이 지수분포를 따르는 경우, 정상상태에서 댐 수위의 확률적 성질들을 구한다. 댐 운영과 관리에 관련된 여러 비용을 고려한 후, 장시간에 걸친 단위시간당 평균 비용을 구하고, 이를 최소화하는 방출률 M과 적정수준${\lambda}$가 유일하게 존재함을 보인다. MATLAB을 이용하여 수치적인 결과도 함께 보인다.

Efficacy of a Cue-Mate Intravaginal Insert and Injection of Prostaglandin $F_{a{\alpha}}$ for Synchronizing Estrus in Hanwoo Cattle

  • Cho, Sang-Rae;Kumar, Kuldeep;Yeon, Seong-Heum;Lee, Sung-Hwan;Kim, Ui-Hyung;Chung, Ki-Yong;Kim, Hyeon-Shup;Lee, Myeung Sik;Park, Chang-Seok;Yang, Byoung-Chul
    • 한국수정란이식학회지
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    • 제29권4호
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    • pp.321-325
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    • 2014
  • The present study was performed on farm animals to test the effectiveness of progesterone-releasing intravaginal device (Cue-Mate$^{(R)}$ 1.56 g) and injection of prostaglandin $F_{2{\alpha}}$ ($PGF_{2{\alpha}}$) for synchronization estrus in Hanwoo cattle. The cattle were at random stage of the estrus cycle. The cows were artificially inseminated at day 7 after Cue-Mate withdrawal, using commercial semen from Korean native bulls. There was a season effect on the estrus synchronization rate. It was higher in spring (94.3%) followed by winter (93.3%), autumn (90.4%) and summer (67.2%). In summary, The results of this study revealed that season has influences on estrus behavior of cattle with no significant effect on pregnancy rate. In summary, we suggest summer reproductive management to alleviate the effects of heat stress. It should be based on intensive cooling combined with hormonal treatment. Given that different subgroups of cows benefit differently from the treatments, selective hormonal administration should be considered.