신경망 모델로 구성한 동해 울릉분지 표층 이산화탄소 분압과 변동성

박소예나,이동섭,조영헌,PARK, SOYEONA,LEE, TONGSUP,JO, YOUNG-HEON 한국해양학회 2016 바다 Vol.21 No.1

동해 표층 해수에서 측정한 이산화탄소 분압($pCO_2$)에 대해 기 확보된 자료는 해양-대기간 $CO_2$ 교환율을 정량화하고자 통계 기법을 적용하기에는 부족한 편이다. 이를 보완하기 위해 위성자료를 이용하여 관측이 이루어지지 않은 해역의 $pCO_2$를 신경망모델을 이용하여 채워 넣는(mapping) 연구를 시도하였다. 본 연구는 동해에서 현장관측자료가 가장 많이 축적된 울릉분지를 대상으로 2003년부터 2012년까지의 표층$pCO_2$자료와, Aqua 위성의 MODIS 센서로 관측한 해표면 온도(SST)와 엽록소(chlorophyll) 자료, 경위도 자료로 신경망모델을 구축하여 $pCO_2$ 분포도 작성과 변동성을 추정하고자 하였다. 신경망모델의 학습은 $pCO_2$ 관측자료와 모델결과값의 상관도가 95% 이상을 달성하도록 하였다. 모델 결과의 평균제곱근오차(RMSE)는 $19.2{\mu}atm$으로 관측자료의 변동 크기와 비교해서 훨씬 작은 수준이었다. SST와 chlorophyll에 연관된 $pCO_2$의 변동성을 살펴보면 chlorophyll 보다는 SST에 대해 더욱 강한 음의 상관 관계를 보였다. 모델이 출력한 $pCO_2$의 변동성은 SST가 내려감에 따라 커지는 경향을 보였다. $15^{\circ}C$ 이하에서는 $pCO_2$ 변동성에 대한 SST와 chlorophyll의 기여도가 뚜렷하게 나타났다. 반면 SST가 $15^{\circ}C$ 이상일 경우에는 $pCO_2$ 변동성은 SST와 chlorophyll의 변화에 대해 그리 민감하게 반응하지 않았다. 신경망모델 출력값으로 추정한 2003-2014년 사이의 울릉분지 표층수의 연평균 $pCO_2$ 증가율은 $0.8{\mu}atm$이었다. 신경망 모델이 울릉분지의 $pCO_2$에 대해 이전 연구보다 해상력과 오차가 향상된 $pCO_2$ 채워넣기를 가능케 해 준 점에 비추어 볼 때 국제정세에 따라 전역 관측이 수월하지 않은 동해의 탄소순환을 이해하는데 유용한 도구로 쓰일 수 있을 것으로 판단된다. Currently available surface seawater partial pressure carbon dioxide ($pCO_2$) data sets in the East Sea are not enough to quantify statistically the carbon dioxide flux through the air-sea interface. To complement the scarcity of the $pCO_2$ measurements, we construct a neural network (NN) model based on satellite data to map $pCO_2$ for the areas, which were not observed. The NN model is constructed for the Ulleung Basin, where $pCO_2$ data are best available, to map and estimate the variability of $pCO_2$ based on in situ $pCO_2$ for the years from 2003 to 2012, and the sea surface temperature (SST) and chlorophyll data from the MODIS (Moderate-resolution Imaging Spectroradiometer) sensor of the Aqua satellite along with geographic information. The NN model was trained to achieve higher than 95% of a correlation between in situ and predicted $pCO_2$ values. The RMSE (root mean square error) of the NN model output was $19.2{\mu}atm$ and much less than the variability of in situ $pCO_2$. The variability of $pCO_2$ with respect to SST and chlorophyll shows a strong negative correlation with SST than chlorophyll. As SST decreases the variability of $pCO_2$ increases. When SST is lower than $15^{\circ}C$, $pCO_2$ variability is clearly affected by both SST and chlorophyll. In contrast when SST is higher than $15^{\circ}C$, the variability of $pCO_2$ is less sensitive to changes in SST and chlorophyll. The mean rate of the annual $pCO_2$ increase estimated by the NN model output in the Ulleung Basin is $0.8{\mu}atm\;yr^{-1}$ from 2003 to 2014. As NN model can successfully map $pCO_2$ data for the whole study area with a higher resolution and less RMSE compared to the previous studies, the NN model can be a potentially useful tool for the understanding of the carbon cycle in the East Sea, where accessibility is limited by the international affairs.

Variability of pCO₂ in surface waters and development of prediction model

Chung, Sewoong,Park, Hyungseok,Yoo, Jisu Elsevier BV 2018 Science of the Total Environment Vol.622 No.-

<P><B>Abstract</B></P> <P>Inland waters are substantial sources of atmospheric carbon, but relevant data are rare in Asian monsoon regions including Korea. Emissions of CO<SUB>2</SUB> to the atmosphere depend largely on the partial pressure of CO<SUB>2</SUB> (pCO<SUB>2</SUB>) in water; however, measured pCO<SUB>2</SUB> data are scarce and calculated pCO<SUB>2</SUB> can show large uncertainty. This study had three objectives: 1) to examine the spatial variability of pCO<SUB>2</SUB> in diverse surface water systems in Korea; 2) to compare pCO<SUB>2</SUB> calculated using pH-total alkalinity (Alk) and pH-dissolved inorganic carbon (DIC) with pCO<SUB>2</SUB> measured by an in situ submersible nondispersive infrared detector; and 3) to characterize the major environmental variables determining the variation of pCO<SUB>2</SUB> based on physical, chemical, and biological data collected concomitantly. Of 30 samples, 80% were found supersaturated in CO<SUB>2</SUB> with respect to the overlying atmosphere. Calculated pCO<SUB>2</SUB> using pH-Alk and pH-DIC showed weak prediction capability and large variations with respect to measured pCO<SUB>2</SUB>. Error analysis indicated that calculated pCO<SUB>2</SUB> is highly sensitive to the accuracy of pH measurements, particularly at low pH. Stepwise multiple linear regression (MLR) and random forest (RF) techniques were implemented to develop the most parsimonious model based on 10 potential predictor variables (pH, Alk, DIC, Uw, Cond, Turb, COD, DOC, TOC, Chla) by optimizing model performance. The RF model showed better performance than the MLR model, and the most parsimonious RF model (pH, Turb, Uw, Chla) improved pCO<SUB>2</SUB> prediction capability considerably compared with the simple calculation approach, reducing the RMSE from 527–544 to 105μatm at the study sites.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Spatial variations of pCO<SUB>2</SUB> were provided with concomitant environmental factors. </LI> <LI> Biases between calculated pCO<SUB>2</SUB> and in situ NDIR measurements were evaluated. </LI> <LI> Calculated pCO<SUB>2</SUB> is highly sensitive to pH measurements, particularly at low pH. </LI> <LI> Environmental factors determining the spatial variability of pCO<SUB>2</SUB> were elucidated. </LI> <LI> pCO<SUB>2</SUB> was predicted properly by the parsimonious RF model (pH, Turb, Uw, Chla). </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

PCO의 주체기관 파견근무에 대한 현상학적 연구

이주향 ( Lee Ju-hyang ),윤은주 ( Yoon Eun-joo ) (사)한국마이스관광학회(구 한국컨벤션학회) 2017 MICE관광연구 Vol.17 No.3

As the convention is based on PCO’s professionalism and by PCO, related services and professional vendors are linked, PCO’s role is one of the most significant role in convention industry. In the convention industry, recognizing the importance of manpower and active research of human resources was been progressed but, from the host organization, empirical research of PCO’s staff dispatch was not done. As an organization in this dissertation we have aimed to analyze experience of PCO’s staff dispatch by using Phenomenological research method and using Giorgi (2004)’s research technique, presenting individual characteristic of experience and common essence was purpose of research. As the result to accept host organization's PCO dispatch request as it is, PCO companies’ manpower structure is limited to accept it. Also, institutionally PCO’s dispatch is ‘contract’ but current situation is formed as ‘dispatch'. This might cause as legal issue. Therefore, host organization should get fair, proper recognition and attitude to PCO. Also upon contract host company has to get enough conference between PCO.

Effects of Enhanced pCO₂ and Temperature on Reproduction and Survival of the Copepod Calanus sinicus

Kang, Hyung-Ku,Lee, Chang-Rae,Kim, Dongseon,Yoo, Sinjae Korea Institute of Ocean ScienceTechnology 2016 Ocean and Polar Research Vol.38 No.4

We tested the combined effects of increased partial pressure of $CO_2$ ($pCO_2$) and temperature on the reproduction and survival of the copepod Calanus sinicus from Asan Bay, the Yellow Sea under laboratory conditions to understand the impact of acidification on copepods. Egg production rate, survival rate, and fecal pellet production of C. sinicus were not affected by 1305 ppm $pCO_2$ or with combined treatments of temperature and $pCO_2$, including $8^{\circ}C$ and 289 ppm $pCO_2$ (ambient), $8^{\circ}C$ and 753 ppm $pCO_2$ (high $pCO_2$), $12^{\circ}C$ and 289 ppm $pCO_2$ (high temperature), and $12^{\circ}C$ and 753 ppm $pCO_2$ (greenhouse), for 5 or 10 d of exposure. However, egg hatching success of C. sinicus decreased significantly in the greenhouse treatment compared with the ambient or the high $pCO_2$ treatments. These results suggest that a combined treatment ($pCO_2$ and temperature) affected egg viability more than a single treatment($pCO_2$).

Effects of Enhanced pCO2 and Temperature on Reproduction and Survival of the Copepod Calanus sinicus

강형구,Chang-Rae Lee,김동선,유신재 한국해양과학기술원 2016 Ocean and Polar Research Vol.38 No.4

We tested the combined effects of increased partial pressure of CO2 (pCO2) and temperature on the reproduction and survival of the copepod Calanus sinicus from Asan Bay, the Yellow Sea under laboratory conditions to understand the impact of acidification on copepods. Egg production rate, survival rate, and fecal pellet production of C. sinicus were not affected by 1305 ppm pCO2 or with combined treatments of temperature and pCO2, including 8oC and 289 ppm pCO2 (ambient), 8oC and 753 ppm pCO2 (high pCO2), 12oC and 289 ppm pCO2 (high temperature), and 12oC and 753 ppm pCO2 (greenhouse), for 5 or 10 d of exposure. However, egg hatching success of C. sinicus decreased significantly in the greenhouse treatment compared with the ambient or the high pCO2 treatments. These results suggest that a combined treatment (pCO2 and temperature) affected egg viability more than a single treatment (pCO2).

Prediction of Surface Ocean pCO2 from Observations of Salinity, Temperature and Nitrate: the Empirical Model Perspective

이현우,이기택,이방용 한국해양과학기술원 2008 Ocean science journal Vol.43 No.4

This paper evaluates whether a thermodynamic ocean-carbon model can be used to predict the monthly mean global fields of the surface-water partial pressure of CO2 (pCO₂SEA) from sea surface salinity (SSS), temperature (SST), and/or nitrate (NO3) concentration using previously published regional total inorganic carbon (CT) and total alkalinity (AT) algorithms. The obtained pCO₂SEA values and their amplitudes of seasonal variability are in good agreement with multi-year observations undertaken at the sites of the Bermuda Atlantic Timeseries Study (BATS) (31°50'N, 60°10'W) and the Hawaiian Ocean Time-series (HOT) (22°45'N, 158°00'W). By contrast, the empirical models predicted CT less accurately at the Kyodo western North Pacific Ocean Time-series (KNOT) site (44°N, 155°E) than at the BATS and HOT sites, resulting in greater uncertainties in pCO₂SEA predictions. Our analysis indicates that the previously published empirical CT and AT models provide reasonable predictions of seasonal variations in surface-water pCO₂SEA within the (sub) tropical oceans based on changes in SSS and SST; however, in high-latitude oceans where ocean biology affects CT to a significant degree, improved CT algorithms are required to capture the full biological effect on CT with greater accuracy and in turn improve the accuracy of predictions of pCO₂SEA. This paper evaluates whether a thermodynamic ocean-carbon model can be used to predict the monthly mean global fields of the surface-water partial pressure of CO2 (pCO₂SEA) from sea surface salinity (SSS), temperature (SST), and/or nitrate (NO3) concentration using previously published regional total inorganic carbon (CT) and total alkalinity (AT) algorithms. The obtained pCO₂SEA values and their amplitudes of seasonal variability are in good agreement with multi-year observations undertaken at the sites of the Bermuda Atlantic Timeseries Study (BATS) (31°50'N, 60°10'W) and the Hawaiian Ocean Time-series (HOT) (22°45'N, 158°00'W). By contrast, the empirical models predicted CT less accurately at the Kyodo western North Pacific Ocean Time-series (KNOT) site (44°N, 155°E) than at the BATS and HOT sites, resulting in greater uncertainties in pCO₂SEA predictions. Our analysis indicates that the previously published empirical CT and AT models provide reasonable predictions of seasonal variations in surface-water pCO₂SEA within the (sub) tropical oceans based on changes in SSS and SST; however, in high-latitude oceans where ocean biology affects CT to a significant degree, improved CT algorithms are required to capture the full biological effect on CT with greater accuracy and in turn improve the accuracy of predictions of pCO₂SEA.

PCO의 멘토링 기능과 경력만족 및 경력몰입에 관한 연구

윤선영(Yoon, Sun-Young) 대한경영학회 2011 大韓經營學會誌 Vol.24 No.5

혐기성소화의 물질분해 및 메탄생성에 대한 CO2 분압의 영향

이국의,김영철,서명교 한국환경보건학회 2000 한국환경보건학회지 Vol.26 No.2

Effects of carbon dioxide partial pressure(PCO2) on bacterial population, methane production rate and matter degradation in anaerobic digestion were investigated by using anaerobic chemostat type reactors at 35 1 , at the HRT of 7 days. At PCO2 of 0.5 atm, the specific methane production rate and specific substrate removal rate reached the maximum rates. The methane production rates in the reactors fed by mixed substrate were 26% higher than those obtained under the controlled condition. The number of acetate consuming methanogenic bacteria enumerated by the MPN(most probable number) method, decreased when PCO2 exceeded 0.7 atm. Hydrogen consuming methanogenic bacteria and homoacetogenic bacteria increased as PCO2 increased from 0.1 to 0.6 atm, however, decreased slightly at PCO2 above 0.7 atm. The number of hydrolytic bacteria, sulfate-reducing bacteria and H2-producing acetogenic bacterial were not much influenced by the change of PCO2. The potential methanogenic activity reached the maximum at PCO2 0.5 atm, however, decreased significantly when PCO2 exceeded 0.7 atm, would depend on free PCO2 concentration in solution

지구시스템모형을 이용한 황동중국해 이산화탄소분압 분포 특성 평가

박영규,최상화,김철호 한국해양과학기술원 2011 Ocean and Polar Research Vol.33 No.4

Using results from an earth system model, the distribution of partial pressure of CO2 (pCO2) in surface seawater over the East China Sea is investigated. In this area pCO2 shows minimum along the edge of the continental break along the path of the Taiwan-Tsushima Current System. Apparently modelled chlorophyll is also great along the current but the maximum of the chlorophyll and the minimum of pCO2do not coincide suggesting that the primary production is not the main cause of the pCO2 minimum. As we move toward the Yellow Sea from the Kuroshio area the temperature decreases so that the pCO2 becomes smaller. If we move further toward the Yellow Sea beyond the Taiwan-Tsushima Current System, alkalinity starts to drop substantially to intensify pCO2 while overcoming the effect of decreasing temperature and salinity. Thus pCO2 minimum occurs along the Taiwan-Tsushima Current System. Of course, the primary production lower pCO2 during spring when it is high but the effect is local. Near the Yangtze river mouth and northeastern corner of the Yellow Sea the fresh water input is large enough and dissolved inorganic carbon (DIC) becomes low enough so that pCO2 becomes lower again.

컨벤션기획업 종사자의 핵심역량 지표 규명에 관한 연구 - 컨벤션기획업의 이해관계자 관점 -

임현주,이태숙 한국관광학회 2013 관광학연구 Vol.37 No.1

본 연구는 컨벤션산업의 핵심적 역할을 수행하고 있는 PCO 종사자의 핵심역량을 심층적으로 검토하고 이를 통해 핵심역량 지표를 도출하고자 하였다. PCO에 종사하는 전문가 15명을 대상으로 심층 인터뷰를 실시하였으며, 심층 인터뷰 및 통계적 검증을 통하여 PCO 종사자의 핵심역량 지표를 도출하였다. 구체적으로는 5개 차원의 16개 항목이며, 그 내용으로는 ‘사교성, 커뮤니케이션기술, 서비스 마인드, 국제적 매너, 고객 needs파악’ 등을 포함하는 ‘의사소통력’ 차원과 컨벤션 업무에 있어 ‘신속한 판단력, 상황 변화 적응력, 위기 및 문제 대처 능력, 행사를 보는 넓은 시각’ 등이 포함된 ‘유연성’ 차원, ‘창의성, 자기개발 노력, 감각 센스’ 등 3개의 항목이 포함된 ‘업무 진행능력’ 차원, ‘팀원 및 조직관리 능력, 행사 성공 전략 구상 능력’이 포함된 ‘기획 및 경영력’ 차원, ‘영어능력, 컴퓨터 운용’이 포함된 ‘외국어 및 기술력’ 차원이 도출되었다. 이러한 결과를 통해 본 연구는 컨벤션 산업 경영성과를 극대화하는데 매우 밀접한 영향력을 발휘하는 종사원들의 핵심역량을 이해관계자의 관점에서 접근하였음에 의의를 둘 수 있다. This paper suggests the core competency index of PCO employees. To effectively achieve its objective, this study establishes the definition and characteristics of "core competency," as well as stating the need for introducing the core competency index for PCO employees based on literature review on the definition and characteristics of PCOs and stakeholders. Due to the lack of earlier researches on PCO employees, this paper includes in-depth interviews conducted on 15 PCO employees, resulting in an index of 53 core competency factors. In the empirical analysis, core competency factors of PCOs have been also confirmed by exploratory factor analyses which have drawn the same five dimensions from 16 items. The core competency scale for PCOs is based on the following five underlying factors: communication, flexibility, ability of business progress, ability of foreign language, and planning and management. This paper draws the conclusion that PCOs must create long-term interests through clients and also make endeavors in increasing the satisfaction of clients by differentiating, managing and reflecting core competencies of PCO employees, as they are required by the clients as corporate survival strategies.