• 한국방재학회 논문집
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• 제6권1호
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• pp.59-68
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• 2006

합류부는 유량의 변화, 흐름방향의 전환으로 순환흐름의 분리구역의 발생에 의한 통수단면의 축소에 의한 통수능의 저하와 이에 따른 배수의 영향이 야기된다. 지류와 본류와의 유량비와 합류각을 달리하면서 실험한 결과를 이용하여 분리구역의 특성을 규명하였다. 분리구역의 정의는 유함수를 이용하여 그 값이 0(영)인 유선을 분리구역으로 정의하여 그 길이와 폭을 본류 하천폭으로 나눈 무차원 길이비와 무차원 폭비로 하였고, 유선에 의한 분리구역의 연구결과가 기존의 실험들과 비교적 잘 맞는 것으로 나타났다. 작은 유량비와 합류각 30도에서는 분리구역이 나타나지 않아서 유량비와 합류각에 의한 분리구역의 출현경계식을 만들었다. 분리구역에 대한 고찰로 합류각, 유량비, 그리고 본류 하류에서의 Froude수에 의한 분리구역의 무차원 길이비와 폭비에 대한 기존의 실험식을 수정하였고, 수굴계수와 형상지수의 수리적 특성을 분석하였다. 일반적으로 유량비와 합류각이 커질수록 분리구역이 크게 나타났다. 합류부를 전후한 상하류 구간에서 수면의 추적에서 유량비와 합류각이 커질수록 배수위의 영향이 크게 나타났고, 합류부가 접하는 내측보다 외측의 배수영향이 크게 나타났다. 하류부 유량에 의해 등류수심을 산정하여 합류가 시작되는 점에서부터 하류의 등류수심에 이르는 곳까지의 거리를 $X_l$로 보고 합류각과 유량비와 단면폭 및 수축계수간의 상관관계식을 산출하였다. 유량비와 합류각에 따른 수로내의 배수위에 의한 최대수위와 분리구역에서의 최소수심과의 비를 분석하였다.

• Journal of Gastric Cancer
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• 제2권3호
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• pp.157-162
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• 2002

Purpose: The prognosis of stage IV gastric cancer is very grave. However, some of these patients survive long periods after surgery. This study was undertaken to investigate various clinico-pathological profiles related to the prognosis for these long-term survivors. Materials and Methods: One hundred fifty-five patients with stage IV gastric cancer who underwent a gastric resection from 1992 to 1997 at Hanyang University Hospital were evaluated. Thirty-three patients who survived more than 5 years after surgery were designated as long-term survivors (LTS); on the other hand, one hundred twenty-two patients who died within 5 years after surgery were named as short-term survivors (STS). Results: The rate of the patients with T4, preoperative serum level of CA19-9 greater than 37 U/g protein, and peritoneal dissemination was lower for the LTS than in for the STS (P=0.002, P=0.045, and P=0.0000, respectively). Tumors were smaller (7.3 cm vs. 8.9 cm, P=0.030) and metastatic lymph node were fewer (19.7 vs. 28.8, P=0.019) for the LTS than for the STS. Curative surgery ($\76\%\;vs.\;\46\%$, P=0.002) and a subtotal gastrectomy ($\76\%\;vs.\;46\%$, P=0.026) were performed more frequently for the LTS than for the STS. From a univariate survival analysis, depth of invasion, distant metastasis, extent of gastric resection, postoperative chemotherapy, and curability were statistically significant factors. From a multivariate survival analysis, curability, depth of invasion, and extent of gastric resection were independent prognostic factors. Conclusions: If feasible, we have to exert our efforts to achieve curative surgery although the tumor is considered to be a stage IV gastric cancer. Thereafter, multi-modality treatments including chemotherapy can be considered to improve the prognosis.

• 한국환경과학회지
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• 제24권2호
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• pp.163-174
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• 2015

The Youngsan Lake was constructed to supply agricultural water to the extensive rice fields in the basin of the lake in 1981. Hypoxia has often developed in the bottom water of the lake during the warm season although the water depth is relatively shallow (< 16 m). We investigated the spatial and temporal variations of dissolved oxygen (DO) and physical properties such as water temperature, salinity and turbidity to elucidate the effects of change in physical properties on DO dynamics in the lake. Vertical profiles of DO, temperature, salinity, and water density were also explored to verify the development of stratification in relation to DO variation in the water column. Hypoxia (DO < $2mg\;L^{-1}$) was not observed in the upper regions whereas hypoxia was detected in the lower regions during the warm season. Thermocline generally developed in the lower regions during the warm season unlike the previous studies in which no thermocline was observed. However, water column was well mixed when freshwater water was discharged from the reservoir through the sluice gate of the dike. DO concentrations also decreased when halocline or pycnocline developed during the dry season suggesting that the vertical stratification of water column affects DO dynamics although the water depth is shallow in the Youngsan lake.

• 지질공학
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• 제7권3호
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• pp.161-171
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• 1997

토공사의 안전시공과 품질향상을 위해서는 지반의 지질구조 및 특성에 대한 정확한 정보의 획득이 무엇보다 중요하다. 지하레이더 탐사법은 수~수십 m 이내의 얕은 심도 지반을 조사할수 있는 간편한 지구물리탐사법의 하나이다. 본 연구는 토공사의 주요한 관심 대상인 지질 경계면 추정에 지하레이데 탐사법을 적용한 사례에 관한 것이다. 탐사지역의 기반암은 안산암이며, 풍화토층, 풍화암층, 연암층 등으로 구성되어 있음이 시추조사 결과로 알려졌다. 여기에 지하레이더 탐사를 실시하여 이들 지질 경계면의 심도를 추정하였다. 지질 경계면 심도를 추정하기 위해서는 지하 매질에서의 전자기파 속도를 분석하여야 하는데, 본 연구에서는 공통 중간점 (CMP, Common Mid-Point) 방법으로 전자기파 평균 속도 0.096m/ns를 구하여 자료를 처리하였다. 이렇게 추정된 심도와 시추조사 결과가 거의 일치하고 있는 점을 확인하였다. 또한 시추조사로는 밝히지 못했던, 연암층 상부경계에서의 차별풍화로 인한 지층의 기복을 확인하였다.

• Ocean and Polar Research
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• 제30권3호
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• pp.277-287
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• 2008

We collected information on seasonal and interannual variability of surface chlorophyll a concentration between 1997-2007 from the Northwest Pacific Ocean. Satellite data were used to acquire chlorophyll a and sea surface temperature from six regions: East Sea/Ulleung Basin, East China Sea, Philippin Sea, Warm Pool region, Warm Pool North region, and Warm Pool East region. Mixed layer depth (MLD) was calculated from temperature profiles of ARGO floats data in four of the six regions during 2002-2007. In the East Sea/Ulleung Basin, seasonal variability of chlorophyll a concentration was attributed to seasonal change of MLD, while there was no significant relationship between chlorophyll a concentration and MLD in the Warm Pool region. Interannual anomaly in sea surface temperature were similar among the East Sea, East China Sea, Philippin Sea, and Warm Pool North region. The anomaly pattern was reversed in the Warm Pool East region. However, the anomaly pattern in the Warm Pool region was intermediate of the two patterns. In relation to chlorophyll a, there was a reversed interannual anomaly pattern between Warm Pool North and Warm Pool East, while the anomaly pattern in the Warm Pool region was similar to that of Warm Pool North except for the El $Ni\tilde{n}o$ years (1997/1998, 2002/2003, 2006/2007). However, there was no distinct relationship among other seas. Interestingly, in the Warm Pool and Warm Pool East regions, sea surface temperature showed a pronounced inverse pattern with chlorophyll a. This indicates a strong interrelationship among sea surface temperature-MLD-chlorophyll a in the regions. In the Warm Pool and Warm Pool East, zonal distribution of chlorophyll a concentration within the past 10 years has shown a good relationship with sea surface temperature which reflects ENSO variability.

• 한국환경과학회지
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• 제21권12호
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• pp.1455-1462
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• 2012

The vertical distributions of nitrifying bacteria in aerobic fixed biofilm were investigated to evaluate the relationship between nitrification performance and microbial community at different HRT. Fluorescent in situ hybridization (FISH) and portable ion selective microelectrode system were adopted to analyze microbial communities and ions profiles according to the biofilm depth. Cilia media packed MLE (Modified Ludzack-Ettinger) like reactor composed of anoxic, aerobic I/II was operated with synthetic wastewater having COD 200 mg/L and $NH_4{^+}$-N mg/L at HRT of 6 hrs and 4 hrs. Total biofilm thickness of aerobic I, II reactor at 4 hrs condition was over two times than that of 6 hrs condition due to the sufficient substrate supply at 4 hrs condition (6 hrs; aerobic I 380 ${\mu}m$ and II 400 ${\mu}m$, 4 hrs; aerobic I 830 ${\mu}m$ and II 1040 ${\mu}m$). As deepen the biofilm detection point, the ratio of ammonia oxidizing bacteria (AOB) was decreased while the ratio of nitrite oxidizing bacteria (NOB) was maintained similar distribution at both HRT condition. The ratio of AOB was higher at 4 hrs than 6 hrs condition and $NH_4{^+}$-N removal efficiency was also higher at 4 hrs with 89.2% than 65.4% of 6 hrs. However, the ratio of NOB was decreased when HRT was reduced from 6 hrs to 4 hrs and $NO_2{^-}$-N accumulation was observed at 4 hrs condition. Therefore, it is considered that insufficient HRT condition could supply sufficient substrate and enrichment of AOB in all depth of fixed biofilm but cause decrease of NOB and nitrite accumulation.

• 한국수산과학회지
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• 제40권3호
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• pp.167-177
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• 2007

We measured the salinity, pH, and concentrations of $^{222}Rn$ and nutrients in groundwater in the southeastern coastal aquifer off Busan from March to September 2005 to evaluate its submarine discharge and geochemical characteristics. Salinity in coastal groundwater increased sharply at 20 m depth and exceeded 25 ppt below 40 m during the study period, indicating that a strong transition zone between fresh groundwater and seawater developed between 20 and 40 m depths. Fresh groundwater in the upper layer of this transition zone was characterized by high pH, $^{222}Rn$, dissolved inorganic nitrogen (DIN), and dissolved inorganic phosphorus (DIP) and low dissolved inorganic silicate (DSi) relative to seawater in the lower layer. In addition, the vertical profiles of the $^{222}Rn$, DIN, and DIP concentrations imply that a strong advective groundwater flow occurs along the interface of fresh groundwater and seawater near 20 m depth. The geochemical constituents in coastal groundwater also showed strong seasonal variation, with the highest concentrations in summer (June 2005) due to the changes of groundwater recharge and sea level. This implies that the input of terrestrial chemical species into the coastal ocean through submarine groundwater discharge (SGD) could change seasonally. To ascertain the seasonal variation of SGD and SGD-driven chemical species fluxes, and associated ecological responses in the coastal ocean, more extensive studies are necessary using various SGD tracers or seepage meters in the future.

• 지구물리와물리탐사
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• 제8권2호
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• pp.119-128
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• 2005

하천에서 발생하는 세굴 과정을 파악하기 위해서 교량 우물통 주변의 침식 그리고 퇴적 양상을 조사하는 것은 필수적이다. 지구물리탐사법은 하천 하상변화를 파악하는데 매우 효과적이며, 과거에 발생한 하상의 세굴 현상을 이해하는데 도움을 줄 수 있다. 본 연구에서는 비파괴 지구물리탐사법인 지하 투과 레이다(Ground Penetrating Radar, GPR)를 이용하여 2002년 6월과 2002년 10월에 한강 내의 교각 주변을 대상으로 홍수전$\cdot$후 세굴에 의한 하상 변화,세굴과 되메움의 범위 및 깊이, 그리고 하상 매질을 조사하였다. 자료획득에는 100 MHz와 400 MHe안테나를 이용한 GSSI SIR 2000 시스템이 사용되었다. 하천의 흐름방향으로 조사한 24개의 교각 사이와 5개 교각의 주위를 돌며 획득된 GPR영상이 비교 제시되었다. 적절한 현장탐사장비와 탐사 절차가 적용된 GPR탐사는 교각 및 교대 주변의 하천 수심과 하상 지질학적 구조를 결정하는데 효과적일 수 있다는 결론을 얻었다.

• 한국전기전자재료학회논문지
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• 제13권1호
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• pp.13-20
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• 2000

In this paper, we demonstrated an analytical description method of forward votage drop and reverse leakage current of the junction barrier controlled schottky rectifier with linearly graded junction and abrupt junction models. In this case, the vertical depths of device are 1[${\mu}{\textrm}{m}$] and 2[${\mu}{\textrm}{m}$], respectively. Through ion implantation and annealing process, we obtain the data of lateral and depth from implanted 2-dimensional profiles. Also we applied these data to models that indicate the change of depletion each on linearly-graded and abrupt juction as the forward and revers bias. After applied depletion changes to electric characteristics of JBS rectifiers, we calculated the forward I-V, the reverse leakage current and temperatures vs. power dissipations according to each junction. When we compared the rectifier with calculated and measured data, from the calculated results, forward votage drop with linearly graded junction is lower than that of abrupt junction and reverse leakage current with linearly graded junction is lower(≒1$\times$10\ulcorner times) than that of abrupt junction. Also, the power dissipations according to different juction depth(1[${\mu}{\textrm}{m}$], 2[${\mu}{\textrm}{m}$]) of device are calculated. Seeing the calculated results, we confirmed it from analytic model that the rectifier with linearly graded junction retained a low power dissipation up to 600[$^{\circ}C$] in comparison with the rectifier with abrupt junction.

• 한국해안해양공학회지
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• 제7권3호
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• pp.277-288
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• 1995

파랑운동하에서 미세한 해저물질로 인한 혼탁도 예측은 해안 또는 호소환경에 민간이 끼친 영향을 평가하는데 있어서 중요하다. 파랑은 이토의 퇴적작용을 완화하고 급격한 부유농도구배를 형성하려는 경향이 있어 해저면 가까이의 퇴적물에 미치는 부하가 대체로 해수면 가까이의 것보다 크다. 물리적으로 실질적이나 단순화된 방법으로 질량보존법칙이 미세입자의 농도분포 진척과 비쇄파 진행파의 작용하에서 해저면 진흙층의 침식에 상당하는 깊이를 모의하는데 사용되어 왔다. 앞서의 현장 관측은 해저면 근처의 모의된 경향을 보여주고 있는데 특성은 농도가 크면 매우 적은 표층토사와 결합되어 진흙층을 액상화시킨다. 결론적으로 해저면 침식 깊이의 예측은 호수역학의 이해와 충분한 현장에서의 토사농도단면측정이 요구된다. 해저면을 무시한 해수면 토사농도만의 측정은 해저면 침식 길이의 총체적인 과소평가를 유발할 수 있다.