• 한국전기전자재료학회논문지
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• 제25권12호
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• pp.974-978
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• 2012

The effect of Cu coating on the sensing properties of nano $SnO_2:Cu$ based sensors for the $CH_4$, $CH_3CH_2CH_3$ gas was studied. This work was focussed on investigating the change of sensitivity of nano $SnO_2:Cu$ based sensors for $CH_4$, $CH_3CH_2CH_3$ gas by Cu coating. Nano sized $SnO_2$ powders were prepared by solution reduction method using stannous chloride($SnCl_2{\cdot}2H_2O$), hydrazine($N_2H_2$) and NaOH and subsequent heat treatment. XRD patterns showed that nano $SnO_2$ powders with rutile structure were grown with (110), (101), (211) dominant peak. The particle size of nano $SnO_2:Cu$ powders at 8 wt% Cu was about 50 nm. $SnO_2$ particles were found to contain many pores, according to SEM analysis. The sensitivity of nano $SnO_2:Cu$ based sensors was measured for 5 ppm $CH_4$ gas and $CH_3CH_2CH_3$ gas at room temperature by comparing the resistance in air with that in target gases. The sensitivity for both $CH_4$ and $CH_3CH_2CH_3$ gases was improved by Cu coating on the nano $SnO_2$ surface. The response time and recovery time of the $SnO_2:Cu$ gas sensors for the $CH_4$ and $CH_3CH_2CH_3$ gases were 18~20 seconds, and 13~15 seconds, respectively.

• International journal of advanced smart convergence
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• 제6권2호
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• pp.59-64
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• 2017

There are three sorts of voices of female vocalists: soprano, mezzo-soprano, and contralto according to the transliteration. Among them, the soprano has the highest vocal range. Since the voice is generated through the human vocal tract based on the voice generation model, it is greatly influenced by the vocal tract. The structure of vocal organs differs from person to person, and the formants characteristic of vocalization differ accordingly. The formant characteristic refers to a characteristic in which a specific frequency band appears distinctly due to resonance occurring in each vocal tract in the vocal process. Formant characteristics include personality that occurs in the throat, jaw, lips, and teeth, as well as phonological properties of phonemes. The first formant is the throat, the second formant is the jaw, the third formant and the fourth formant are caused by the resonance phenomenon in the lips and the teeth. Among them, pronunciation is influenced not only by phonological information but also by jaws, lips and teeth. When the mouth is small or the jaw is stiff when pronouncing, pronunciation becomes unclear. Therefore, the higher the accuracy of the pronunciation characteristics, the more clearly the formant characteristics appear in the grammar spectrum. However, many soprano singers can not open their mouths because their jaws, lips, teeth, and facial muscles are rigid to maintain high tones when singing, which makes the pronunciation unclear and thus the formant characteristics become unclear. In this paper, in order to confirm the accuracy of the pronunciation characteristics of soprano singers, the experimental group was selected as the soprano singers A, B, C, D, E of Korea and analyzed the grammar spectrum and conducted the MOS test for pronunciation recognition. As a result, soprano singer B showed a clear recognition from F1 to F5 and MOS test result showed the highest recognition rate with 4.6 points. Soprano singers A, C, and D appear from F1 to F3, but it was difficult to find formants above 2kHz. Finally, the soprano singer E had difficulty in finding the formant as a whole, and MOS test showed the lowest recognition rate at 2.1 points. Therefore, we confirmed that the soprano singer B, which exhibits the most distinct formant characteristics in the grammar spectrum, has the best pronunciation accuracy.

• 디지털융복합연구
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• 제15권11호
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• pp.113-120
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• 2017

본 연구에서는 금융위기를 전후하여 기업이 보유한 부동산 중 업무용부동산과 투자부동산의 보유비중이 어떻게 변화되었는지를 분석하고, 이 부동산의 보유비중이 금융위기를 전후하여 코스피기업과 코스닥기업간에 차이가 있는지 여부를 분석하였다. 코스피기업의 경우 투자부동산은 개략적으로 증가하고 업무용부동산은 개략적으로 감소하였다. 코스닥 기업의 경우 금융위기 중의 투자부동산을 제외하고 코스피기업과 유사하였다. 평균차이분석을 이용하여 코스피기업과 코스닥기업을 비교해보면, 금융위기 직전에는 코스피기업의 보유부동산비중이 코스닥기업의 보유부동산비중 보다 투자와 업무용 모두 낮았으나, 금융위기 중 구간에는 코스피기업의 업무용부동산비중이 코스닥기업의 업무용부동산비중 보다 높아졌으며, 금융위기 직후 구간과 최근 구간까지는 코스피기업의 투자부동산비중이 코스닥기업의 투자부동산비중 보다 높게 유지되고 있었다. 본 연구는 금융위기 전후의 업무용부동산과 투자부동산의 변화 현상을 파악하는 목적이며, 이 분석결과를 토대로 경영성과와의 관련성 파악을 향후연구과제로 남긴다.

• ALGAE
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• 제29권4호
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• pp.355-366
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• 2014

Fucoxanthin is known to be an effective cell proliferation inhibitor with anti-tumor and anti-angiogenic activities. However, there is a lack of data regarding the biological effects of cis isomers of fucoxanthin. To assess the potential therapeutic properties of 9'-cis-(6'R) fucoxanthin (FcA), and 13-cis and 13'-cis-(6'R) fucoxanthin complex (FcB) isolated from Sarggassum siliquastrum, we investigated their inhibitory effects on matrix metalloproteinases (MMPs) in phorbol 12-myristate 13-acetate (PMA)-induced human fibrosarcoma (HT1080) cells. FcA and FcB reduced MMP-2 and MMP-9 protein and mRNA levels, as well as the migration of these cells, in a dose-dependent manner. Additionally, FcA and FcB increased levels of MMPs inhibition factors such as tissue inhibitor of metalloproteinase-1. FcA and FcB significantly inhibited the transcriptional activity of nuclear factor ${\kappa}B$ (NF-${\kappa}B$) and by inhibiting c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases. Our results demonstrate that suppression of the NF-${\kappa}B$, JNK, and p38 signaling pathways may inhibit PMA-induced MMP-2 and MMP-9 activity. Therefore, FcA and FcB may be useful in noninvasive therapeutic strategies against fibrosarcoma metastasis.

• Composites Research
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• 제31권3호
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• pp.88-93
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• 2018

본 연구에서는 입자크기가 서로 다른 할로이사이트 나노튜브(Halloysite nanotube, HNT)와 밀드 카본(Milled carbon, MC) 강화 복합재료를 사용하여 손상된 복합재료 적층판을 계단형 패치 보수법에 따라 수리하고, 손상된 면과 수리면 사이의 접합 계면에 입자가 미치는 기계적, 구조적 영향을 분석하였다. 이 때, 고온고습의 가혹한 수분 환경에 장시간 노출시켜 손상된 판을 형성하는 기존 재료와의 상대적인 재료 물성 회복률을 비교하였으며 기계적 물성 시험을 통해 성능평가를 실시하였다. 그 결과 $70^{\circ}C$ 고온 증류수에서 HNT는 입자 첨가량에 따라 흡습률이 MC에 비해 뚜렷한 차이를 보였으며 인장강도와 굽힘강도의 경우, 대체적으로 HNT로 강화된 복합재를 사용하여 보수한 시험편이 흡습 전과 후 모두 높은 수치를 나타냈다. 특히, 0.5, 1 wt. %의 HNT가 첨가되었을 때 흡습률이 가장 적었고 이는 기계적 강도 증가에 관여하는 하나의 요인으로 작용하였다. 반면 MC는 소량만으로도 높은 흡습 저항성을 나타냈으며 하중의 방향에 따라 강도의 차이가 발생했다.

• 한국수자원학회논문집
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• 제53권1호
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• pp.1-13
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• 2020

높은 레이놀즈수를 갖는 공학적인 흐름을 예측하는 가장 일반적인 방법은 여전히 벽함수를 이용하는 난류모형에 근거한 RANS 수치모의이다. 최근 벽근처의 점성영역 관계식과 벽에서 떨어진 대수영역 관계식을 혼합하여 개발된 일반화된 벽함수들은 두 영역사이의 난류량과 유속이 부드럽게 천이하도록 한다. 이 연구는 난류운동에너지(TKE), 에너지 소산율, 비소산율, 와점성에 대해서 적용 가능한 벽함수들을 조합하여 일련을 수치 모의를 수행하여 널리 이용되고 있는 난류모형들의 성능과 수렴 특성을 분석하였다. 이 연구 결과는 RNG k-𝜖 모형의 경우 첫번째 계산격자가 완충층에 놓이게 될 때는 반복 계산시 작은 허용오차를 이용하여 주의 깊게 적용을 하여야 안정된 해를 구할 수 있음을 보여준다. 표준 k-𝜖과 RNG k-𝜖 모형은 TKE와 와점성에 대해서 적용 가능한 벽함수들 중 어느 것을 선택하여 적용하더라도 수치모의 결과가 민감하게 반응하지 않는 것으로 나타났다. 한편, k-ω SST 모형의 경우 TKE에 대해서는 kL-벽함수 그리고 와점성에 대해서는 nutUB-벽함수를 이용하여야 정확하고 안정된 경계 조건 설정을 보장할 수 있다. 레이놀즈수 155,000조건에서 적용한 후방계산흐름 수치모의 결과 격자 해상도에 상관없이 약 13% 정도 재부착 거리를 과소평가하는 모형을 제외하고 나머지 적용한 난류모형들 모두 적절히 세밀한 해상도의 격자에서 양호하게 재부착거리를 잘 예측하는 것으로 나타났다.

• Ocean and Polar Research
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• 제33권1호
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• pp.21-34
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• 2011

We determined potential meso-scale benthic-pelagic ecosystem coupling in the north equatorial Pacific by comparing surface chl-a concentration with sediment bacterial abundance and adenosine triphosphate (ATP) concentration (indication of active biomass). Water and sediment samples were latitudinally collected between 5 and $11^{\circ}N$ along $131.5^{\circ}W$. Physical water properties of this area are characterized with three major currents: North Equatorial Current (NEC), North Equatorial Count Current (NECC), and South Equatorial Current (SEC). The divergence and convergence of the surface water occur at the boundaries where these currents anti-flow. This low latitude area ($5{\sim}7^{\circ}N$) appears to show high pelagic productivity (mean phytoplankton biomass=$1266.0\;mgC\;m^{-2}$) due to the supplement of high nutrients from nutrient-enriched deep-water via vertical mixing. But the high latitude area ($9{\sim}11^{\circ}N$) with the strong stratification exhibits low surface productivity (mean phytoplankton biomass=$603.1\;mgC\;m^{-2}$). Bacterial cell number (BCN) and ATP appeared to be the highest at the superficial layer and reduced with depth of sediment. Latitudinally, sediment BCN from low latitude ($5{\sim}7^{\circ}N$) was $9.8{\times}10^8\;cells\;cm^{-2}$, which appeared to be 3-times higher than that from high latitude ($9{\sim}11^{\circ}N$; $2.9{\times}10^8\;cells\;cm^{-2}$). Furthermore, sedimentary ATP at the low latitude ($56.2\;ng\;cm^{-2}$) appeared to be much higher than that of the high latitude ($3.3\;ng\;cm^{-2}$). According to regression analysis of these data, more than 85% of the spatial variation of benthic microbial biomass was significantly explained by the phytoplankton biomass in surface water. Therefore, the results of this study suggest that benthic productivity in this area is strongly coupled with pelagic productivity.

• International Journal of Contents
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• 제10권1호
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• pp.54-61
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• 2014

In this paper, we propose a pioneering concept of DPD(Disaster Prevention Design) to realize a securable society in the future. Features of danger in the future society are expected to be diverse, abrupt occurring, large scale, and complicated ways. Due to increment of dangers with their features of uncertainty, interactivity, complexity, and accumulation, human-oriented design concept naturally participates in activities to prevent our society against disasters effectively. We presented DPD is an essential design activity in order to cope with dangers expected in the future societies as well as realize securable environments. DPD is also an integrated design aids including preemptive protections, rapid preparing, recovery, and interactive cooperation. We also expect these activities of DPD is effective for generation of new values in the market, satisfaction of social needs, expansion of design industry, and a novel chance for development in the future society. Throughout this paper, we submit various aspects of DPD concepts including definition, classification, scope, necessity, strategy, influencing elements, process, and its principle. We expect these concepts will be the seed and/or basement of DPD research for the future works. For the direction of study for DPD in the future, we emphasize alarm system for preemptive protection rather than recovery strategy for the damage occurred. We also need to research about progressive prevention techniques and convergence with other areas of design. In order to transfer the concept of product design from facility-oriented mechanism to human-oriented one, we should develop new kinds of city basis facilities, public-sense design concepts referred to social weak-party, e-Learning content design preparing disasters, and virtual simulation design etc. On the other hand, we have to establish laws and regulations to force central and/or provincial governments to have these DPD strategies applying their regional properties. Modern design activities are expanding to UI(user interface) content design area overcoming the conventional design concept of product and/or service. In addition, designers are recognized as art directors or life stylists who will change the human life and create the social value. DPD can be divided into prevention design, preparedness design, response design, and recovery design. Five strategies for successful DPD are Precaution-oriented, Human-oriented, Sense-oriented, Legislation, and Environment Friendly Strategies.

• 대한공업교육학회지
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• 제38권1호
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• pp.275-297
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• 2013

발명 교사 교육 표준은 발명 내용학 내용 표준과 발명 교육학 내용 표준으로 구분된다. 이 연구는 발명 내용학 내용 표준을 개발하는데 목적이 있다. 연구의 목적을 달성하기 위한 연구의 방법으로 연구팀 회의, 문헌 고찰, 내용 분석, 개발 연구, 조사 연구, 타당성 검증을 이용하였다. 연구의 결과 개발된 발명 내용학 내용 표준 체계는 10가지의 대영역 발명의 개념과 특성, 발명과 사회, 생활 속의 발명, 창의성 계발, 발명과 설계, 발명 문제 해결, 융합 지식과 발명, 발명 프로젝트, 지식 재산과 특허 출원, 발명과 기술 경영로 구성된다. 그리고 10가지의 대영역은 20가지의 핵심내용(중영역), 90가지의 하위요소로 구성된다. 발명 내용학 내용 표준은 추후 교재를 개발하는데 학문적 기반을 마련해 주었을 뿐만 아니라 향후 발명 교육을 전개할 경우 참조적 표준으로 가치가 충분하다.

• 한국의학물리학회지:의학물리
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• 제28권4호
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• pp.207-217
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• 2017

For effective patient treatment in proton therapy, it is therefore important to accurately measure the beam range. For measuring beam range, various researchers determine the beam range by measuring the prompt gammas generated during nuclear reactions of protons with materials. However, the accuracy of the beam range determination can be lowered in heterogeneous phantoms, because of the differences with respect to the prompt gamma production depending on the properties of the material. In this research, to improve the beam range determination in a heterogeneous phantom, we derived a formula to correct the prompt-gamma distribution using the ratio of the prompt gamma production, stopping power, and density obtained for each material. Then, the prompt-gamma distributions were acquired by a multi-slit prompt-gamma camera on various kinds of heterogeneous phantoms using a Geant4 Monte Carlo simulation, and the deduced formula was applied to the prompt-gamma distributions. For the case involving the phantom having bone-equivalent material in the soft tissue-equivalent material, it was confirmed that compared to the actual range, the determined ranges were relatively accurate both before and after correction. In the case of a phantom having the lung-equivalent material in the soft tissue-equivalent material, although the maximum error before correction was 18.7 mm, the difference was very large. However, when the correction method was applied, the accuracy was significantly improved by a maximum error of 4.1 mm. Moreover, for a phantom that was constructed based on CT data, after applying the calibration method, the beam range could be generally determined within an error of 2.5 mm. Simulation results confirmed the potential to determine the beam range with high accuracy in heterogeneous phantoms by applying the proposed correction method. In future, these methods will be verified by performing experiments using a therapeutic proton beam.