• 한국항해항만학회지
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• 제39권1호
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• pp.77-82
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• 2015

슬래밍은 선체가 파도와 부딪히며 선수, 선미에서 강한 충격압력을 받아 급격한 진동이 발생되는 현상이다. 이러한 슬래밍은 사람에게는 승선감의 불쾌감을 주고, 선체에는 구조적인 위험을 주며 화물의 안전과도 깊은 관계가 있다. 따라서 선박 설계기준에는 슬래밍에 의한 충격압력을 충분히 고려한 구조설계를 해야 한다. 본 연구에서는 자유낙하 하는 쐐기형 구조물의 중량 및 낙하높이의 변화에 따른 슬래밍 충격 압력 및 유동장의 유동특성을 알아보고자 실험을 수행하였다. 유동장의 계측은 2-프레임 그레이레벨 상호상관 PIV기법을 이용해 접수와 이수로 구분하여 실험하였으며, 충격압력의 계측은 압력계측장비인 Dewetron System을 이용하였다. 실험에서 모델과 자유수면간 이루는 각도는 $15^{\circ}$를 적용하였으며 이때, 중량의 변화는 1.5, 1.8 및 2.0kg이고 자유낙하높이는 100, 200 및 300mm로 하여 실험하였다. 실험값을 통한 중량의 변화에 따른 충격압력은 중량의 증가하는 것에 비례하여 충격압력 또한 증가했으며, 이러한 경향은 자유낙하 높이가 높을수록 영향을 많이 받았다.

• 한국패류학회지
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• 제25권2호
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• pp.97-103
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• 2009

본 연구에서 바지락 부유 유생은 저질입경이 클수록 착저율(${\Omega}_b$)이 높았으며, 생물적으로도 저질을 선택하고 있다는 것을 확인할 수 있었다. 또 침투류의 발생에 의한 유동장에 있어서는 유속이 10 cm/s, 저질 중앙입경 1.211 mm, 침투 유속 0.3 cm/s일 경우, 3.1-5.1 배의 부유 유생 착저 효과 $\alpha$ (=${\Omega}_b/{\Omega}_{b0}$)가 증가되는 것을 확인하였다. 부유 유생에 있어서 저질입경의 선택성은 생물적인 요인에 의존하고, 유동장에 있어서 착저 촉진 효과는 물리적인 안정 조건에 지배되어 있었다. 그리고 이번 새롭게 도입한 안정 지표(${\lambda}p$)에 의해 통일적으로 평가할 수 있는 것을 확인하였다. 유생의 안정 지표(${\lambda}p$)에 의하면, 유속이 작용했을 경우의 부유 유생은 저질입경에 영향을 받지 않고 거의 일정 값을 가지며, 초기 이동한계유속 및 전면 이동 한계유속에 대응하는 ${\lambda}p$값은 각각 0.14, 1.06 이였고, 새롭게 제안한 안정 지표(${\lambda}p$)의 타당성이 검증되었다. 따라서 본 연구 결과에 의해 어떤 해역의 바지락 부유 유생의 부유 밀도, 저질 입경, 유동 조건이 명확할 때, 바지락 부유 유생의 착저율을 추측할 수 있는 결과를 얻을 수 있었다.

• Journal of Acupuncture Research
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• 제15권2호
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• pp.255-277
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• 1998

The aim of this experiment was to investigate the effects of Aqua-Acupuncture of Yukmijiwangtang(六味地黃湯) and Palmijihwang-tang(八味地黃湯) water extracts applied at the meridian points BL 23(賢兪) and GV 4(命門) to test the renal function in normal rats. The results obtained were as follows; 1. Among the effects of Aqua-Acupuncture of Yukmijihwangtang water extract at the merdian point BL 23 group, there were significant changes in water balance and urine volume over a 1 week period; Both decreasing and decreasing trends were exihibited. Urinary excretion of sodium and free water clearance changed significantly over a 2 week period; Both decreasing and increasing trends were exihibited, Urinary excretion of potassium, chloride and creatinine, plasma renin activity, plasma levels of aldosterone and atrial natriuretic peptide showed no significant differences compared to the contral group. 2. Among the effects of Aqua-Acupuncture of Palmljihwangtang water extract at the merdian point BL 23 group, there were significant changes in water balance and free water clearance over a 2 week period; a decreasing trend. Urinary excretion of creatinine changed significantly over a 2 week period; an increasing trend. Urinary excretion of chloride changed significantly over 1 week period; an increasing trend. The plasma levels of atrial natriuretic peptide changed significantly over 1 and 2 week period; an increasing trend. Urine volume, urinary excretion of sodium and pottasium, plasma renin activity and plasma level of aldosterone showed no significant differences compared to the control group. 3. Among the effects of Aqua-Acupuncture of Yukmijihwangtang water extract at the meridian point GV 4 group, there was significant decrease in water balance over a 2 week period; there was significant decrease in urine volwne and urinary excretion of sodium and creatinine over a 1 week period, followed by an increasing trend after 2 weeks. Urinary excretion of free water clearance demonstrated significant changes over both 1 and 2 week period; both increasing and decreasing trends were exihibited. Urinary excretion of chloride and plasma levels of aldosterone increased significantly over 1 and 2 week period. Plasma levels of atrial natriuretic peptide also decreased significantly. Plasma renin activity showed no significant differences compared to the control group. 4. Among the effects of Aqua-Acupuncture of Palmijihwangtang water extract at the meridian point GV 4 group, water balance and urinary excretion of chloride, plasma levels of aldosterone decreased significantly over both 1 and 2 week period. Urine volume and urinary excretion of pottasium decreased significantly. Urinary excretion of creatinine and urinary excretion of sodium changed significantly over both 1 and 2 week period. Urinary excretion of free water clearance, plasma renin activity and plasma level of atrial natriuretic peptide showed no significant differences compared to the control group. Seeing these results, I come to know that the effects Aqua-Acupuncture of Yukmijihwangtang and Palmijihwangtang water extracts at the meridian point BL 23 and GV 4 have affected the renal function differently. Seeing the results that BL 23 is a meridian point for Aqua-Acupuncture directly related to the kidney, I think, we can use Aqua-Acupuncture of Yuk-mijihwangtang and Palmijihwangtang water extracts to prevent and to treat the diseases related to kidney.

• 한국식품영양과학회지
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• 제18권2호
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• pp.199-204
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• 1989

오징어육속에 함유되어 있는 주요유리당 성분을 조사하고 이들 성분의 추출용매와 추출시간에 따른 변화를 조사하였다. 오징어육의 주요 유리당성분은 glucose, fructose ribose이며 이들의 양이 전체의 80%이상을 차지하였고 galactose, xylose, mannose도 소량 검출되었다. 추출조건에 따라서는 생오징어의 경우는 물로서 추출하는 것이, 건조오징어의 경우는 70%에탄올로 추출하는것이 유리당의 추출량을 증가시킬 수 있었다. 추출시간에 따른 유리당의 추출량은 추출온도 $100^{\circ}C$이하에서는 추출용매에 관계없이 $2{\sim}3$시간 추출한 것이 가장 높게 나타났고, $120^{\circ}C$의 고온에서는 추출 1시간에 가장 높고, 그 이후에서는 급속히 감소하는 현상을 보였다.

• 대한조선학회논문집
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• 제40권4호
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• pp.22-29
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• 2003

New high-speed depressurized circulating water channel was designed by using the CFD code. Flow in the channel has free surface and pressure in the test section can be depressed. In this study, Flow separation and bubble occurrence were considered in designing the contraction nozzle shape for better flow uniformity Tn the test section. To supplement velocity defect due to the free surface, nozzle injection system more effective in high-speed flow was installed instead of drum system. Necessary power and injection techniques were proposed. And guide vane arrangement was analyzed to reduce the flow resistance and keep quiet free surface from ´surging´. Wave absorber was devised to reduce the wave resistance and to prevent the entrainment of air to the diffuser.

• 한국가시화정보학회지
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• 제6권2호
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• pp.28-32
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• 2008

Contrary to the flow rate in fully filled pipe flows, the flow rate in partially filled pipe flows is significantly influenced by the variation of water level, channel slop, and so on. The major difference in these two flows results from the existence of a free surface. To make it clear, in the present study, a similarity of the velocity profile in a partially filled circular pipe has been investigated according to the water level. A particle image velocimetry (PIV) technique was applied to measure the three-dimensional velocity profiles. As a result, there is found a similarity of the velocity profile near the central region. However, near the side wall, the similarity is broken due to the interaction between the wall and the free surface.

• 한국수자원학회논문집
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• 제50권5호
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• pp.289-302
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• 2017

발산형 바닥 경사 생성항(DFB, Divergence Form for Bed slope source term)을 엄밀하게 유도하였으며, DFB 중에서 격자의 변에서 평균 수심을 이용하는 mDFB의 오차를 명백하게 입증하였다. 또한, DFB 기법은 바닥 경사 생성항에 대해 정확한 방법임을 밝혔다. 완전히 잠기기 않은 격자에 대한 기존의 체적-수심 관계의 오류를 수정하였으며, C-특성의 충족을 위해 완전히 잠기지 않은 변에 대한 처리가 필요함을 검토하였다. 이 연구를 통해 근사 Riemann 해법으로 천수방정식을 해석할 때 보다 정확한 수단을 제공할 수 있을 것으로 기대한다.

• 설비공학논문집
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• 제9권2호
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• pp.104-111
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• 1997

The freezing phenomenon of saturated water with the supercooled region in a horizontal circular cylinder has been studied experimentally by using the holographic real time interferometry technique. From the experiments, it was found that there were three types of freezing patterns. The first is the annular ice layer growing from the cylinder surface at a high cooling rate; the next is the asymmetric ice layer at a moderate cooling rate; and the last is the instantaneous ice layer growth over the full region at lower cooling rate. As the water was coolde from room temperature to the subfreezing point passing through the density inversion point, the freezing pattern was largely affected by the inversion phenomenon, which had much effected the free convection and was susceptible to influences from the cooling rate. When the cooling rate is high, supercooling energy is released before the water is sufficientry mixed by free convection. On the other hand, when the cooling rate is low, there is much time for the water to be mixed by free convection. This seems to be the reason why the different ice layer growths occur.

• 한국환경복원기술학회지
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• 제6권6호
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• pp.41-48
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• 2003

Nitrogen removal rate and emergent plant growth were investigated of a free-water-surface constructed treatment wetland system, whose dimensions were 31m in length and 12m in width. The system was constructed on floodplain in the Kwangju Stream from May to June 2001. Cattails(Typha angustifolia) were transplanted from natural wetlands and their stems were cut at about 40cm height from their bottom ends. Water of the Kwangju Stream were funneled into the system by gravity flow and its treated effluent was discharged back into the stream. The average height of the cattail stems was 45.2cm in July 2001 and 186cm in October 2001. The number of stems averaged 22 stems/$m^2$ in July 2001 and 52 stems/$m^2$ in September 2001. Volume and water quality of inflow and outflow were analyzed from July 2001 through December 2001. Inflow and outflow averaged 40.01 and 39.55 $m^3$/day, respectively. Hydraulic detention time was about 1.5 days. Average nitrogen uptake by cattails was 69.31 $N\;mg\;m^{-2}\;day^{-1}$. Removal rate of $NO_3-N$, $NH_3-N$ and T-N averaged 195.58, 53.65 and 628.44 $mg\;m^{-2}\;day^{-1}$, respectively. The average removal rate of T-N was about 39%.

• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.809-814
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• 2011

A method based on the TMS derivatives and acidic hydrolysis was developed for the simultaneous determination of free and conjugated steroidal hormones in surface water. A silylation of five natural and two synthetic steroidal hormones was achieved with N-methyl-N-(trimethylsilyl) trifluoroacetamide/$NH_4I$ (1000:3) under catalysis of dithioerythritol for 60 min at $80^{\circ}C$. TMS derivatives of the steroid hormones containing multifunctional groups offer a single derivative product under this condition. The accuracy of the analytes was in the range of 87 to 110% at a concentration of 20 and 50 ng/L with relative standard deviations of less than 10%. The method detection limit was in the range of 0.01 to 0.02 ng/L for surface water. Natural steroidal hormones were detected in a concentration range of 0 to 1.03 ng/L in free form and 0 to 14.6 ng/L in conjugated form, respectively. We found that most of the natural hormonal steroids exist in conjugate forms (43 to 100%) in river water.