• Journal of Energy Engineering
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• v.13 no.4
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• pp.296-300
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• 2004

Performance evaluation and economic estimation were conducted on the water to water GSHP (Ground Source Heat Pump) installed in existing building. Ground heat exchanger was a closed vertical loop type and sized to be 5 boreholes and 100m depth per borehole. Operation efficiency of the system shows that, COP increased from 3.0 to 4.2 with entering water temperature in heating operation, however, COP decreased from 5.0 to 3.7 in cooling operation. Economic estimation was analyzed by LCC (Life Cycle Cost) method and it showed that GSHP could save 68% of cost compare to the conventional oil source. Thus, despite of the large amount of initial cost, GSHP has a economic advantage to the other energy sources.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.9
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• pp.1689-1695
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• 2008

The development of low-power wireless communication and low-cost multi-functional smart sensor has enabled the sensor network that can perceive the status information in remote distance. Sensor nodes are sending the collected data to the node in the base station through temporary communication path using the low-cost RF communication module. Sensor nodes get the energy supply from small batteries, however, they are installed in the locations that are not easy to replace batteries, in general, so it is necessary to minimize the average power consumption of the sensor nodes. It is known that the RF modules used for wireless communication are consuming 20-60% of the total power for sensor nodes. This study suggests the probability inference heuristic based non-periodic transmission to send the collected information to the base station node, when the calculated value by probability is bigger than an optional random value, adapting real-time to the variation characteristics of sensing datain order to improve the energy consumption used in the transmission of sensed data. In this transmission method suggested, transmitting is decided after evaluation of the data sensed by the probability inference heuristic algorithm and the directly sensed data, and the coefficient that is needed for its algorithm is decided through the reappearance rate of the algorithm verification data.

• Nuclear Engineering and Technology
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• v.16 no.3
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• pp.125-130
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• 1984

In the application of the RETRAN code to the analysis of very small LOCA one of main concerns is placed on use of the bubble rise model in the upper plenum, because the bubble rise model nay cause a numerical divergence problem and coefficients used to describe it are based on experimental results of large LOCA. In order to solve this problem, a method, which enables us to predict the mixture level in the upper plenum without use of the bubble rise model, was proposed. For this method the local void distribution in the core and upper plenum was derived by using a simplified slip model. It was shown that results predicted from the derived equation are in excellent agreement with experimental data. Additionally it was found that local void in the upper plenum has a uniform distribution unlike a linear distribution in large LOCA. Communication between the upper plenum and upper head was investigated. By introducing the concept of Taylor instability, it was proved that counter-current Hon between them is possible.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.395-395
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• 2015

하천 내 식생은 수리학, 지형학 및 생태학적으로 매우 중요하다. 식생은 하천 수생물들의 서식처를 제공할 뿐만 아니라 필터와 같은 역할을 함으로써 부유사에 의한 하천오염물의 퇴적을 유발하여 하천의 수질을 개선시킨다. 더욱이, 하천 내 흐름 및 난류구조를 변경시킴으로써 식생주변의 유사 퇴적량 및 분포에 크게 영향을 미치고, 결국 하천의 지형을 변화시킨다. 개수로의 식생에 대한 영향은 주로 실험 및 수치모델을 이용하여 연구되었고 전단면이 식재된 조건에서 식생의 항력계수, 식생역내의 부유사 및 확산에 관한 연구가 진행되어왔다. 이러한 연구를 통해 식생역 내의 전단력이 감소하여 부유사퇴적이 증가하고 식생역과 비식생역 사이의 운동량 교환에 의해 부유사 퇴적이 증가함을 보였다. 그러나 개수로에서 존재하는 유한한 크기의 식생에 의한 흐름 및 유사분포에 관한 연구는 아직 미흡하다. 이에 본 연구에서는 침수하지 않은 원형 식생 주변에서 발생하는 흐름특성을 수치모의 하였다. 침수하지 않은 원형식생 하류에서 발생하는 흐름을 계산하기 위해 2차원 수치모형을 적용하였다. 식생에 의한 저항을 고려하기 위해 운동량 방정식에 식생항을 추가하였고 $k-{\varepsilon}$ 난류모형을 적용하였다. 수치모의 조건은 Zong and Nepf (2012)의 수리실험을 참고하여 수로의 길이는 12 m, 폭은 1.2 m로 설정하였다. 0.13 m 수심을 갖는 개수로에 0.22 m 지름을 갖는 원형식생을 상류경계로부터 1.0 m 떨어진 곳에 설정하였다. 식생의 밀도($6{\sim}77m^{-1}$)를 변화시키면서 원형식생 하류의 흐름거동을 분석하였다. 식생밀도가 높은 경우에는 원형식생 양 측면에서 유발된 전단층들의 상호작용에 의해 하류에서 와류가 발생하였다. 와류가 발생하는 위치에서 난류강도가 가장 크게 나타났다. 그러나 식생밀도가 일정 값보다 낮아지면 와류가 발생하지 않는 것으로 나타났다.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.299-299
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• 2023

토양수분(soil moisture)은 수문인자의 하나로서 토양 내에 함유된 물의 양을 의미하며, 그 총량은 미미하지만 대기와 지표면 사이에서 일어나는 복잡한 물순환과 에너지 교환을 이해하는데 있어 필수적이다. 현재 국내에서는 「수자원의 조사·계획 및 관리에 관한 법률」(이하 수자원법)에 근거해 토양수분량 관측이 이루어지고 있으며, 수자원 분야의 한국수자원조사기술원 외에도 농업, 임업 분야에서도 다양한 기관에서 지상관측소를 구축해 토양수분량을 측정하고 있다. 국내 지상관측소에서는 주로 지점규모(point scale)로 토양수분량을 관측하는 장비가 사용되고 있으며, 유전율식 장비인 TDR(Time Domain Reflectometry), FDR(Frequency Domain Reflectometry)이나 토양수분장력을 측정하는 장력계(Tensiometer)가 널리 쓰이고 있다. 수자원분야에서는 토양 내 수분의 양을 직관적으로 확인할 수 있는 유전율식 장비가 대중적으로 사용되고 있으며, 최근에는 우주선(Cosmic-Ray)으로부터 발생하는 고속중성자(Fast Neutron)를 통해 중규모 면단위(field scale) 토양수분량을 관측하는 장비인 CRNP(Cosmic-Ray Neutron Probe)에 대한 연구도 활발히 진행되고 있다. 이러한 장비는 주로 야외에 설치해 운영하고 있기 때문에 장비 훼손이나 전원공급의 어려움으로 결측이나 오측이 발생할 수 있다. 토양수분량 시계열자료의 결측이나 오측이 일반적인 감쇄기에 발생했다면 선형보간법으로도 간단히 보간할 수 있지만, 강우에 의한 상승기에 발생했다면 해당 강우사상에서의 토양수분량의 상한치를 알기 어려워 결측보간에 어려움이 있다. 본 연구에서는 토양수분량 시계열자료의 강우기간 결측을 보간하는 방법으로 누적분포함수 역변환 샘플링방법을 선택하였다. 연구에는 음성군(차곡리) 토양수분량 관측소 2021년 자료가 사용되었으며, 관측소 56개 지점 중 임의의 지점에 결측구간을 생성한 뒤 해당 지점과의 상관계수가 높은 지점의 누적분포함수를 이용해 역변환 샘플링 방식으로 임의 지점의 결측을 보간하고 그 결과를 기존값과 비교해 보간 방법의 정확도를 평가하였다.

• Tuberculosis and Respiratory Diseases
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• v.51 no.2
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• pp.97-107
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• 2001

Background : Tuberculosis itself causes not only lung parenchymal destruction but also pulmonary vascular damage. Secondary emphysema also causes pulmonary vascular damage, which can develop as a late sequela of pulmonary tuberculosis. Therefore, pulmonary circulatory impairment tends to be more severe in post-tuberculosis emphysema than in primary emphysema. In post-tuberculosis emphysema, the right ventricular function may play an important role. However, little information regarding the right ventricular function is available. The purpose of this study was to evaluate and compare the right ventricular function between post-tuberculosis emphysema and primary emphysema. Method: Post-tuberculosis emphysema(PTE) or primary emphysema(PE) was diagnosed by history, HRCT finding and pulmonary function. Twenty patients with post-tuberculosis emphysema were matched with 20 patients with primary emphysema according to both $FEV-1$ and FVC. Arterial blood gas analysis and echocardiography were done at rest and immediately after symptom-limited exercise. The right ventricular function was evaluated with the right ventricular ejection fraction using a modification of Simpson's method. Results : There was no significant difference in the demographics and pulmonary function between the two groups. In post-tuberculosis emphysema, the $PaCO_2$ was higher ($42.9{\pm}4.7$ vs $38.8{\pm}3.1\;mmHg$ at rest; $47.9{\pm}7.0$ vs $41.1{\pm}5.9\;mmHg$ after exercise; p<0.01) and the right ventricular ejection fraction was lower ($57.6{\pm}6.5$ vs $61.4{\pm}4.7%$ at rest; $51.1{\pm}10.8$ vs $59.8{\pm}6.6%$ after exercise; p<0.01) both at rest and after exercise. The $PaCO_2$ after exercise was also lower ($65.7{\pm}12.6$ vs $80.2{\pm}14.4\;mmHg$, p<0.01), while the Pa02 at rest tended to be lower($82.9{\pm}12.0$ vs $87.8{\pm}7.5$, p>0.05). In both groups, right ventricular ejection fraction correlated with the $PaCO_2$ after exercise(PTE r=0.536, PE r=0.557), and the $PaCO_2$ at rest(PTE r=-0.576, PE r=-0.588) and after exercise(PTE r=-0.764, PE r=-0.619). Conclusion : Impairment of the right heart function and gas exchange were more serious in post-tuberculosis emphysema than in primary emphysema, and gas exchange may be influenced by the right ventricular function in post-tuberculosis emphysema.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.4
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• pp.220-227
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• 2004

Phosphorus desorption study is essential to understanding P behavior in agricultural and environmental soils because phosphorus is considered as two different aspects, a plant nutrient versus an environmental contaminant. This study was conducted to determine soil P buffering power related to P desorption quantity intensity (Q/I) parameters, $Q_{max}$(an index of P release capacity) and $l_0$(an index of the intensity factor), and to investigate the characteristics of relationship between the P desorption Q/I parameters and the soil properties. Soil samples were prepared with treatments of 0 and $100mg\;P\;kg^{-1}$ applied as $KH_2PO_4$ solution. The P desorption Q/I curves were obtained by a procedure using anion exchange resin beads and described by an empirical equation ($Q=aI^{-1}+bln(I+1)+c$). The P desorption Q/I curves for the high available P (${\g}20mg\;kg^{-1}$ of Olsen P) soils were characteristic concave trends with or without soil P enrichment, whereas for the low available P (${\lt}20mg\;kg^{-1}$ of Olsen P) soils, the anticipated Q/I concave curves could not be obtained without a proper amount of P addition. When the soils were enriched in phosphates, the values of desorbed solid phase labile P and solution P, such as $Q_{max}$ and $I_0$ respectively, were increased, but the ratio of $Q_{max}$ versus $I_0$ was decreased. Thus, the slope of desorption Q/I curve represented as phosphorus buffering power, $|BP_0|$, is decreased. The $|BP_0|$ values of the high available P soils ranged between 48 and $61L\;kg^{-1}$ in the P untreated samples and between 18 and $44L\;kg^{-1}$ in the P enriched samples. Overall $|BP_0|$ values of both low and high available P soils treated with $l00mg\;P\;kg^{-1}$ ranged between 14 and $79L\;kg^{-1}$. The $Q_{max}$, values ranged between 71.4 and $173.1mg\;P\;kg^{-1}$, and the lo values ranged between 0.98 and $3.82mg\;P\;L^{-1}$ in the P enriched soils. The $Q_{max}$ and $I_0$ values that control the P buffering power may be not specifically related to a specific soil property, but those values were complicatedly related to soil pH, clay content, soil organic matter content, and lime. Also, phosphorus release activity, however, markedly depended on the desorbability of the applied P as well as the native labile P.

• Korean Journal of Soil Science and Fertilizer
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• v.9 no.1
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• pp.1-8
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• 1976

1. Under an asumption that Ficks diffusion equation could be applicable in soil systems, the diffusivities of NaCl in several flooded soil systems were measured to range from $0.4{\times}10^{-5}cm^2sec^{-1}$ to $0.83{\times}10^{-5}cm^2sec^{-1}$ 2. It was discussed that, when a polder soil with a uniform initial salt content through the profile is desalinated only by diffusion to flooding water, the salt content in profile is a function of soil depth, diffusion time, and diffusivity as following $$C=C^{\circ}erf\frac{x}{\sqrt[2]{Dt}}$$ 3. On the basis of Kirkham, et al's integration of complementary erra function, the speed of desalting was discussed to be inversely proportional to the square root of time as following $$dq/dt=C^{\circ}{\sqrt{D/{\pi}t}}$$ 4. It was estimated enough to exchange the flooding water once or twice, even when desalination of polder soil is carried out only by diffusion, if the desalination begins in June, the used flooding water is fresh water, and flooding depth is 10cm. 5. Desalination of polder soil by diffusion requires 2 month for good standing of planted rice.

• Analytical Science and Technology
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• v.16 no.4
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• pp.299-308
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• 2003

The purpose of this study is to investigate cadmium concentrations among metals in ETS (Environmental Tobacco Smoke) of indoor environments and to evaluate the cadmium as a marker of ETS. The correlations of cadmium concentrations and nicotine, 3-EP, RSP, SD (Smoking Density), and SI (Smoking Index). Air samples of metals, nicotine, 3-EP, and RSP were taken in smoking room, smoking allowed office, corridor outside smoking room, and non-smoking office respectively. The SD, ACH, and SI were investigated during sampling. Airborne concentration of cadmium known as human carcinogen were qualified and quantified. The SD was 0.2 to $2.6cig/m^2{\cdot}hr$, and the mean value of SD in smoking rooms was $1.2cig/m^2{\cdot}hr$ that is higher than other researches. The mean of ACH in smoking rooms was 11.1. The concentrations of cadmium showed log-normal distributions and the geometric mean concentrations of cadmium in smoking rooms, corridor outside smoking rooms, smoking allowed offices, and non-smoking offices were $0.045{\mu}g/m^3$, $0.018{\mu}g/m^3$, $0.021{\mu}g/m^3$, and $0.017{\mu}g/m^3$ respectively. The concentrations of cadmium in smoking room showed significant difference according to category of indoor office environments (p<0.05) and showed compliance with occupational exposure limits. The correlation coefficients between cadmium and nicotine, 3-EP, and RSP were 0.53, 0.41, 0.43 respectively. The cadmium among metals showed the highest correlations (r=0.63) with SI. It was recommended cadmium among metals is a good indicator for ETS.

• 한국해양학회지
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• v.10 no.1
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• pp.33-40
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• 1975

The ion exchange sorption and elution behavior of toxic heavy metal ions, such as Hg(II) and Zn(II), have been studied in aqueous and methanolic media of MCl (M: K, Na and NH$\_$4/). The ion exchange resins studied are Dowex 1-X8, Cl$\^$-/ (50-100 or 200-400 mesh) and Dowex 50W-X8, M$\^$+/ form (M: K, Na, NH$\_$4/ and H). the sorption and elution of metal ion on the resin is largely due to the formation of the anionic chlororocomplex of metal ion. The addition of methanol in the medium contributes markedly to the distribution data. In order to apply this work for the treatment of polluted sea water with toxic heavy metal ions, removal experiment of the metal ions from the synthetic sample solution was investigated.