• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.1-12
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• 2006

For advanced civil engineering structures a service life of hundred up to hundred fifty and even two hundred years is sometimes required. The prediction of the performance of concrete structures over such a long period requires accurate and reliable predictive models. Most of the presently used, mostly experience based models don't have the quality and reliability that is required for reliable long-term predictions. The models designers are searching for should be based on an accurate description of the relevant degradation mechanisms. The starting point of such models is a realistic description of the microstructure of the concrete. In this presentation the need and the role of fundamental microstructural models for predicting the performance of concrete structures will be presented. An example will be given of a microstructural model with a proven potential for long-term predictions. Besides this also the role of models in general, i.e. in the whole design and execution process of concrete structures, will be dealt with. Finally recent trends in concrete research will be presented, like the research on self-healing cement-bases systems.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2007년도 추계학술대회 논문집
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• pp.507-508
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• 2007

• Asian Journal of Atmospheric Environment
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• 제11권4호
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• pp.235-253
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• 2017

This study was conducted for analyzing the contribution factors on ozone concentrations and its long term trends in each major city and province in Korea through several statistical methods such as simple linear regression, generalized linear model, KZ-filer, correlation matrix, Kringing method, and cluster analysis. The overall ozone levels in South Korea have been consistently increasing over the past 10 years. The ozone concentrations in Seoul, the biggest city in Korea, are the lowest in all areas with the highest increasing ratio for $95^{th}%$ ozone. It is thought that the active photochemical reaction could affect the higher ozone concentration increase. On the other hand, the ozone concentrations in Jeju are the highest in Korea with the highest increasing ratio for $5^{th}%$, $33^{th}%$, and $50^{th}%$ ozone. It is also thought that the weak $NO_x$ titration could be the reason of higher ozone concentrations in Jeju. In case of Jeju, transport related factors is the major factor affecting the ozone trend. Thus, it is assumed that the variation of ozone trend of Asian region affecting the ozone trend in Jeju, where domestic ozone photochemical reaction is less active than urban area. It is thought that the photochemical reaction plays the role of increasing of ozone concentrations in the urban area, even though the LRT affected on the increase of ozone concentrations in non-urban area.

• 한국정보통신학회논문지
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• 제20권12호
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• pp.2274-2281
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• 2016

장기생태연구 커뮤니티에서 개인정보는 국가단위 뿐만 아니라 국제장기생태연구의 데이터 관리, 데이터 활용에서 협업을 위한 중요한 요소이다. 개인정보를 많은 부분 공개를 하면 협업 연구자에게 데이터 접근 측면에서 유용하지만, 정보 제공자에게는 공개에 대한 부담이 되기도 한다. 개인의 정보보호 관련 법률에서는 개인정보의 수집범위와 유통측면에서 많은 제약 요소가 존재하여 장기생태정보시스템에서도 장기생태연구 협업에 필요한 최대의 개인정보와 비 관련자에게 제공하는 최소의 개인정보 제공이 고려되어야 한다. 본 연구는 국내외 데이터 교류를 위해 관련 법률의 해석을 기반으로 국제 메타데이터 표준인 EML과 국제 장기생태 플랫폼의 개인정보 관리에 대한 동향을 분석하고 개인정보 관리를 위한 시스템 모델을 설계 및 구현을 통해 제시하고자 한다.

• Journal of Gastric Cancer
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• 제16권4호
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• pp.240-246
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• 2016

Purpose: It is hypothesized that robotic gastrectomy may surpass laparoscopic gastrectomy after the operators acquire long-term experience and skills in the manipulation of robotic arms. This study aimed to evaluate the long-term learning curve of robotic distal gastrectomy (RDG) for gastric cancer compared with laparoscopic distal gastrectomy (LDG). Materials and Methods: From October 2008 to December 2015, patients who underwent LDG (n=809) were matched to patients who underwent RDG (n=232) at a 1:1 ratio, by using a propensity score matching method after stratification for the operative year. The surgical outcomes, such as trends of operative time, blood loss, and complication rate, were compared between the two groups. Results: The RDG group showed a longer operative time (171.3 minutes vs. 147.6 minutes, P<0.001) but less estimated blood loss (77.6 ml vs. 116.6 ml, P<0.001). The complication rate and postoperative recovery did not differ between the two groups. The RDG group showed a longer operative time and similar estimated blood loss compared with the LDG group after 5 years of experience (operative time: 159.2 minutes vs. 136.0 minutes in 2015, P=0.003; estimated blood loss: 72.9 ml vs. 78.1 ml in 2015, P=0.793). Conclusions: In terms of short-term surgical outcomes, RDG may not surpass LDG after a long-term experience with the technique.

• 한국산학기술학회논문지
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• 제17권6호
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• pp.676-686
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• 2016

본 연구는 국내 리츠가 운용된 2002년부터 2015년까지의 리츠사의 타인자본에 대한 차입이자율을 월별 자료로 구축하여 차입이자율의 흐름과 금리변수와의 관계를 분석하였다. 선행연구를 검토한 결과 리츠사의 차입이자율은 리츠 내부의 고유요인에 의해 결정되기도 하지만 거시경제변수 중 금리변수와 연계성이 높게 나타났다. 이에 본 연구는 K-REITs 차입이자율과 금리 변수 간에 ARDL(autoregressive distributed lag: 자기회귀시차) 모형을 설정하여 장기관계를 분석하였으며, ARDL-ECM 모형을 기반하여 단기 관계도 검토하였다. 실증분석 결과 K-REITs 차입이자율과 국고채 3년, 국고채 5년, 회사채(AA-,3년), 기업일반자금 대출금리에서 장기 공적분 관계가 형성되었으며, 이는 K-REITs 차입이자율이 장기금리 변수와 동조하고 있음을 보여준다. 또한, 기업일반자금 대출금리는 장기 관계와 단기 조정 과정에서도 K-REITs 차입이자율과의 연계성이 높게 나타났다. REITs가 금융권 차입에 관한 사항과 경영계획 수립 시에 기업일반자금 대출금리와 같은 장기금리 변수의 동향 등을 고려하여 의사결정 한다면 K-REITs 발전에 실질적인 도움이 될 수 있을 것이다.

• 한국대기환경학회지
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• 제32권4호
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• pp.360-371
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• 2016

The goal of this research is to examine the recent decade-long (2000~2014) trends of national background concentrations over China, Japan, and Korea. Based on the Long-range Transboundary Air Pollutants in Northeast Asia (LTP) project, which is three-party collaboration project among three countries, we investigated the long-term trends of national background $PM_{10}$ concentrations in three countries over the recent 15 years, including the 2008 Beijing Olympic Game period. In accordance with the agreement among three countries, a total of 8 national background sites: three national background monitoring sites in China (2 sites in Dalian, and 1 in Xiamen), three sites in Korea (Ganghwa, Gosan, and Taean), and two sites in Japan (Oki and Rishiri), were chosen for the trend analysis. The results showed that Chinese background concentration recorded the highest level overall. However, the rapid declining recent trends of annual median ($50^{th}$-percentile) values were surprisingly detected since 2006 or 2007 in every site in China, with the most rapidly decreasing rate (- $18.6{\pm}10.3%$/year) over 2006~2007, and the second most rapidly decreasing rate (- $18.0{\pm}1.5%$/year) over 2007~2008. Based on the previous statistical literature, we concluded that this declining trends were due to the emission reduction of $PM_{10}$ concentrations in China for 2008 Beijing Olympic Game. In Korea, Ganghwa was also showing the decreasing trends over the recent years since 2006, which is also well accorded with the decreasing period of Chinese background concentrations. Taean also implied some impact of Beijing Olympic Game, showing small but detectable decreasing trends, while Gosan showed the increasing tendencies probably due to the near-urban influences. However, since 2012, most sites in both China and Korea showed strong increasing trends, undoubtedly implying the increasement of both emission in China and its long-range transport process toward Korea. Two sites in Japan, Oki and Rishiri recorded the lowest level of $PM_{10}$ level during whole period with the smallest deviations of measurements. Other discussions including the decade-long trends of $5^{th}$, $10^{th}$, $25^{th}$, $50^{th}$, $75^{th}$, $90^{th}$, $95^{th}$-percentiles of $PM_{10}$ background concentrations in three countries were also comparatively addressed here.

• 생태와환경
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• 제44권2호
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• pp.214-225
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• 2011

The objectives of the study were to evaluate seasonal patterns of epilimnetic water quality, and determine interannual eutrophication patterns at the dam site of Yong-dam Reservoir using long-term data during 2002~2009. Ionic dilutions, based on specific conductivity, occurred in the summer period in response to the intense monsoon rain and inflow, and suspended solid analysis indicated that the reservoir was clear except for the monsoon. Seasonality of nitrogen contents varied depending on the types of nitrogen and responded to ionic dilution; Ammonia-nitrogen ($NH_4$-N) peaked at dry season but nitrate-nitrogen ($NO_3$-N) peaked in the monsoon when the ionic dilution occurred. The maxima of $NO_3$-N seemed to be related with external summer N-loading from the watershed and active nitrogen fixation of bluregreens in the summer. $NO_3$-N was major determinant (>50%) of the total nitrogen pool and relative proportion of $NH_4$-N was minor. Long-term annual $NO_3$-N and TDN showed continuous increasing trends from 2004 to 2009, whereas TP and TDP showed decreasing trends along with chlorophyll-a (CHL) values. Empirical model analysis of log-transformed nutrients and N : P ratios on the CHL showed that the reservoir CHL had a stronger linear function with TP ($R^2$=0.89, p<0.001) than TN ($R^2$=0.35, p=0.120). Overall results suggest that eutrophication progress, based on TP and CHL, is slow down over the study period and this was mainly due to reduced phosphorns, which is considered as primary nutrient by the empirical model.

• 한국해양학회지:바다
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• 제23권2호
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• pp.63-75
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• 2018

본 연구에서는 분위회귀를 이용하여 1993~2016년 동안의 한반도 조위 자료의 장주기 선형 추세를 분석하였다. 일반 선형회귀(OLS: Ordinary Least Square)와 50% 중간 분위 회귀 결과를 비교했을 때 특히 황해에서 약 2~3 mm/year의 회귀 결과의 차이를 발견하였으며, 이는 극한 값 변화에 기인함을 확인할 수 있었다. 또한 해역별로 하위(1%) 분위와 중간(50%) 분위, 상위(99%) 분위의 값이 모두 다르게 나타났다. 황해의 대부분 지역에서는 상위 분위와 하위 분위가 모두 증가하는 경향을 나타냈으나, 유의미한 "상향 발산형" 회귀 결과를 보였다. 이는 상위 분위가 중간 분위에 비해 유의미하게 크게 나타나는 경향을 의미한다. 대한민국 남해안에서는 상위 분위가 하위 분위보다 더 작은 증가 값을 가지는 "상향 수렴형" 회귀 결과가 특징적으로 나타났다. 이러한 경향은 조화 분석을 통해 알려진 조석 분조들을 제거한 결과에서는 없어지는 것을 확인하였다. 그러므로 분위 회귀의 지역적 특성은 조석 세기의 장주기 변동과 연관이 있다고 추측된다.

• The Korean Journal of Pain
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• 제37권1호
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• pp.73-83
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• 2024

Background: Failed back surgery syndrome (FBSS) is a chronic condition that is characterized by persistent back pain following one or more spinal surgeries. Pharmacological interventions, such as the use of opioids and gabapentinoids, are frequently used in the treatment of FBSS. However, prolonged and excessive use of these medications can lead to dependence and adverse effects. This study investigates trends in opioid and gabapentinoid prescriptions among patients with FBSS in Korea from 2016 to 2020. Methods: Data from the Health Insurance and Review Agency were analyzed, and claims listing FBSS were selected for the study. Prescription patterns of opioids and gabapentinoids were classified based on the number of days prescribed per year. Results: Of the 390,095 patients diagnosed with FBSS, 41.6% of the patients were prescribed gabapentinoids, and 42.0% of them were prescribed opioids, while 10.6% of the patients were classified as long-term gabapentinoid users, 11.4% as long-term opioid users, and 7.4% of the patients were found to have long-term prescriptions for both drugs. The proportion of patients who received both gabapentinoid and opioid prescriptions increased annually. The doses of opioids prescribed have also increased along with the increase in the number of patients receiving opioid prescriptions. Conclusions: The prescription rates of opioids and gabapentinoids among patients with FBSS in Korea continue to increase steadily, posing potential risks of addiction and adverse effects. Further research is needed to better understand the actual status of addiction in patients with FBSS.