• 대한전기학회논문지:시스템및제어부문D
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• 제49권8호
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• pp.442-450
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• 2000

Active noise control is an approach to noise reduction in which a secondary noise source that destructively interferes with the unwanted noise. In general, active noise control systems rely on multiple sensors to measure the unwanted noise field and the effect of the cancellation. This paper develops an approach that utilizes a single sensor. The noise field is modeled as a stochastic process, and a time-adaptive algorithm is used to adaptively estimate the parameters of the process. Based on these parameter estimates, a canceling signal is generated. Opppenheim model assumed that transfer function characteristics from the canceling source to the error sensor is only propagation delay. But this paper proposes a modified Oppenheim model by considering transfer characteristics of acoustic device and noise path. This transfer characteristics is adaptively cancelled by adaptive model. This is proved by computer simulation with artifically generated random noise and sine wave noise. The details of the proposed architecture, and theoretical simulation and experimental results of the noise cancellation system for three dimension enclosure are presented in the paper.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.301-304
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• 2006

For the purpose of investigating the contributions of various gases to climate change, the thermal radiation associated with greenhouse gases are extracted from AIRS (Atmospheric Infrared Sounder) infrared radiances over the tropical pacific region. AIRS instrument which was launched on the EOS-Aqua satellite in May 2002 covers the spectral range from 650 cm-1 to 2700 cm-1 with a spectral resolution of between 0.4 cm-1 and 1 cm-1. In order to extract the thermal radiation absorbed by individual gases, the interfering background radiances at the top of the atmosphere are simulated using the radiative transfer code MODTRAN (MODerate spectral resolution atmospheric TRANsmittance). The simulations incorporated the temperature and water vapor profiles taken from NCEP (National Centers for Environmental Prediction) reanalyses. The differences between the simulated background radiance and AIRS-measured radiance result in the absorption of upward longwave radiation by atmospheric gases (i.e. greenhouse effect). The extracted absorption bands of individual gases will allow us to quantify the radiative forcing of individual greenhouse gases and thus those data will be useful for climate change studies and for the validation of radiative transfer codes used in general circulation models.

• 설비공학논문집
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• 제29권4호
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• pp.149-158
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• 2017

In general, the air-side j and f factors of evaporators or condensers are obtained through single-design tests performed under air-dry and wet-bulb temperatures. Considering that the indoor or outdoor air temperatures vary significantly during the operation of an air conditioner, it is necessary to confirm that the experimentally-obtained j and f factors are widely applicable under variable air conditions. In this study, a series of tests were conducted on a two-row slit-finned heat exchanger to confirm the applicability. The results showed that, for the dry-surface condition, the changes of the tube-side water temperature, water-flow rate, and air temperature had virtually no effect on the air-side j and f factors. For the wet condition, however, the f factor was significantly affected by these changes; contrarily, the j factor is relatively independent regarding this change. The formulation of the possible reasoning is in consideration of the condensation behavior underneath the tube. The wet-surface j and f factors are larger than those of the dry surface, with a larger amount for the f factor.

• 한국수정란이식학회지
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• 제14권3호
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• pp.163-169
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• 1999

This study was carried out to investigate the effect of co-culture system(bovine oviduct epithelial cells; BOEC) and defined culture system(modified TALP ; mTALP) on the development of IVM-IVF embryos, and survival of in vitro produced blastocysts after freezing and thawing. Occytes from the slaugheterhous ovaries were matured and fertilized using general protocol. The results obtained were as the following: 1. Survival rates of frozen-thawed blastocysts using 10% glycerol as cryoprotectant was higher in day 7 blastocysts than in Day 8 and 9 blastocysts from co-cultrue system, but survival rate of frozen-thawed blastocysts was higher in Day 10 blastocysts than in day 8 and 9 blastocysts from defined culture system. Regardless of their age, survival rate of frozen-thawed blastocysts was significantly higher (p<0.05) in co-culture system than in defined culture system. 2. The cell number of blastocysts was significanlty higher (p<0.05) in Day 7 blasotcysts than in Day 8 and 9 blastocysts from co-cultures, but the cell number of blsstocysts was significantly higher (p<0.05) in Day 10 blastocysts than in Day 8 and 9 blastocysts from defined culture system. Regardless of the culture system, blastocysts with higher cell number showed higher survival rates after freezing and thawing.

• Journal of Photoscience
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• 제10권1호
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• pp.1-7
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• 2003

The results of recent work on the dye-sensitized photooxygenation of sulfides is discussed. In the case of dialkyl sulfides, the weakly bonded adduct initially formed with singlet oxygen (the persulfoxide) decays unproductively unless protonation by an acid (an alcohol or a carboxylic acid) facilitates its conversion to the sulfoxide. The effect is proportional to the strength of the acid (eg., less than 0.1 % chloroacetic acid in benzene is sufficient for maximal efficiency) and corresponds to general acid catalysis, suggesting that protonation of the persulfoxide occurs. On the other hand, with sulfides possessing an activated hydrogen in ${\alpha}$ position (eg., benzyl and allyl sulfides), hydrogen transfer becomes an efficient process in aprotic media and yields a S-hydroperoxysulfoniumm ylide, possibly arising from a conformation of the persulfoxide that is different from the one protonated in the presence of acids. Calculations on some substituted sulfides support this hypothesis. This process, which leads to C-S bond fragmentation with formation of an aldehyde, may be viewed as a general method for the preparation of aryl and heteroaryl aldehydes. In this effort, mechanistic studies offered new hints on the structure of the intermediate persulfoxide.

• 산업융합연구
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• 제20권8호
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• pp.41-52
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• 2022

기업 교육훈련은 조직구성원 및 조직의 성과 향상을 위해서 시행되나 실제 교육훈련의 성과는 기대한 만큼 나타나고 있지 않다. 이에 따라 본 연구에서는 기업 내 교육성과를 피교육자의 조직몰입도와 업무성과로 정의하고 이에 영향을 미치는 요인들에 대해 연구함으로써 성과 창출을 위해 기업 교육훈련 설계 시 고려해야 하는 것들을 제안한다. 우선 기업 교육훈련에서 제공되는 교육콘텐츠 특성으로서의 과제가치와 직무연관성, 그리고 기업 내 교육훈련에 대한 지원 정도인 조직특성이 피교육자의 교육전이에 영향을 끼치는 지 확인한다. 이후, 교육전이로부터 조직몰입 및 업무성과로의 인과관계를 분석한다. 이 과정에서 온/오프라인 교육의 조절효과가 있는지 분석하여 교육 전달 방법에 따른 효과성의 차이가 있는지 검증한다. 연구결과, 교육의 과제가치, 직무연관성, 조직보상이 교육전이에, 교육전이가 조직몰입 및 업무성과에 유의한 영향을 미치는 것으로 나타났으며, 온/오프라인 교육간 차이가 있음을 입증하였다. 본 연구는 프랜차이즈 기업을 대상으로 수행하여 표본의 한계가 존재하며, 향후 대표성을 지닌 표본이나 전문직종의 집단을 대상으로 연구를 확장할 예정이다.

• 한국철도학회논문집
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• 제9권2호
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• pp.180-186
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• 2006

In this study, a large-scale laboratory model test, 2-D and 3-D numerical analyses were conducted to verify the reinforcement effect by utilizing geotextile bag on the railway roadbed. Static loading which simulated train load was applied on the geotextile bag-reinforced railway roadbed and also unreinforced railway roadbed, Computer program named Pentagon which is a part of FEM programs was used in the numerical analysis. Based on the results of laboratory test, 2-D and 3-D numerical analyses, the effect of load distribution and settlement reduction was found to be depending on the geotextile characteristics, tensile strength of geotextite, and interface friction angle between geotextile bags. In general, the result of 2-D and 3-D numerical analyses shows lower value than that of laboratory test. Also, the result of 3-D numerical analyses shows lower value than that of 2-D numerical analyses because of its stress transfer effect.

• 대한음성학회:학술대회논문집
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• 대한음성학회 2006년도 추계학술대회 발표논문집
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• pp.113-116
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• 2006

In this paper, we first implement an audio playback system for virtual reality by providing 3D audio effects to listeners. In general, such a 3D audio playback system utilizes a sound localization technique using head related transfer function (HRTF) to generate 3D audio effect. However, the 3D audio effect is degraded due to the crosstalk in the stereo loudspeaker environment. To enhance the 3D sound effect, we implement the crosstalk cancellation technique proposed by Atal and Schroeder and apply it to the 3D audio system.

• Bulletin of the Korean Chemical Society
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• 제17권8호
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• pp.693-695
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• 1996

The steric effect on the first order hyperpolarizability of the β-nitrostyrene derivatives has been investigated by comparing the β values and the dihedral angles between the aryl and nitroalkenyl groups. In general the β value increased with the electron-donating ability of the substituent. The larger β value for 3,4-dimethoxy-β-nitrostyrene than that for p-methoxy-β-nitrostyrene has been attributed to the lower charge transfer energy for the former. The most striking substituent effect was observed in the β-methyl-β-nitrostyrene derivatives. Thus the β values for 3,4-dimethoxy- and p-methoxy derivatives of the latter decreased to near zero, probably because of the large distortion from planarity caused by the steric repulsion between the β-methyl and the aryl groups. The larger β value for p-dimethylamino-β-methyl-β-nitrostyrene has been interpreted with an increased electron-donating ability of the substituent and increased co-planarity.

• Clinical and Experimental Reproductive Medicine
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• 제22권2호
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• pp.143-148
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• 1995

To present and assess the efficacy of combination of microsurgical epididymal sperm aspiration(MESA) and intracytoplasmic sperm injection(ICSI) for the treatment of infertility due to unreconstructable obstructive azoospermia or congenital bilateral agenesis of vas deferens (CBAVD), MESA was performed in the 45 husbands ( 16 CBAVD, 29 unreconstructable genital tract obstruction), followed by ICSI of oocytes recovered from the wives hyperstimulated by GnRH agonist in combination with hMG and FSH. Cleaving embryos were transfered to the uterine cavity or follopian tube(ZIFT) 18 or 24 hours after ICSI procedure. In 45 cycles of MESA, 492 oocyte complexes were recovered. ICSI was carried out on 355 metaphase II oocytes and 226 oocytes (63.7%) showed normal two pronucleus fertilization. After 198 embryos were transferred in 43 cycles, an average of 5 per cycle, 20 patients presented a positive HCG and intrauterine pregnancy was confirmed by US. So, the clinical ongoing pregnancy rate per transfer was 46.5%. Until now, 8 patients have given birth to 9 babies, 5 male and 4 female, including 1 twin. The babies were all healthy except 1 twin female baby. There was 1 miscarriage at 7 weeks and chromosomal study of abortus revealed as 45X, monosomy. These results suggested that it was possible to achieve high normal fertilization and pregnancy rate by ICSI using epididymal sperm.