• Journal of Environmental Science International
• /
• v.23 no.3
• /
• pp.511-520
• /
• 2014

The MFFn(Mass first flush), EMCs(Event mean concentrations) and runoff loads were analyzed for various rainy events(monitoring data from 2011 to 2012) in transportation area(rail road in station). The pollutant EMCs by volume of stormwater runoff showed the BOD5 9.6 mg/L, COD 29.9 mg/L, SS 16.7 mg/L, T-N 3.271 mg/L, T-P 0.269 mg/L in the transportation areas(Railroad in station). The average pollutant loading by unit area of stormwater runoff showed the BOD5 $27.26kg/km^2$, COD $92.55kg/km^2$, SS $50.35kg/km^2$, T-N $10.13kg/km^2$ and T-P $10.13kg/km^2$ in the transportation areas. Estimated NCL-curve(Normalized cumulated-curve) was evaluated by comparison with observed MFFn. MFFn was estimated by varying n-value from 10% to 90% on the rainy events. The n-value increases, MFFn is closed to '1'. As time passed, the rainfall runoff was getting similar to ratio of pollutants accumulation. The result of a measure of the strength of the linear relationship between observed data and expected data under model was good.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.39 no.12
• /
• pp.1207-1212
• /
• 2015

A vibro ripper utilizes high-frequency vibration for rock fragmentation. This concept is different from those used by other existing breakers. The gearbox-shank welded joint of a vibro ripper is a very important part. Because it delivers the vibromotive force to the tooth, it is important to predict its soundness. This study was conducted to predict the fatigue life under welding conditions. The shank materials were Hardox-Hituf and AR400, and the filler metals were CSF-71T and CSF-81T. Fatigue tests were conducted under each set of conditions. P-S-N curves are presented based on the statistical testing method recommended by JSME-S002, and a comparison is made of the results under each set of conditions. The life was estimated using a P-S-N curve.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.25 no.2
• /
• pp.250-256
• /
• 2017

Automatic transmission(A/T) is one of a car's core components. The durability of A/T has an effect on the durability of the car. The input shaft of A/T passes the power directly from the engine, so the durability of the input shaft for A/T is likewise vital. In this study, the test method of the input shaft is considered and the load spectrum of A/T is analyzed to secure durability of the input shaft. The shape parameter, T-N curve of the input shaft torsional fatigue test are obtained for life evaluation and analysis. Results of this study can be used to get the basic background of the durability test for A/T components.

• Proceedings of the KIEE Conference
• /
• 2000.07b
• /
• pp.840-842
• /
• 2000

DC모터의 T-N(토크-회전수)특성이 선형성을 갖는다는 사실은 널리 알려져 있다. 더욱이 인덕턴스가 작은 소형 모터의 경우에는 T-N특성이 거의 직선에 가깝게 된다. 그러나 대형모터일수록 인덕턴스가 커지므로 이 인덕턴스의 영향으로 T-N특성은 비선형의 곡선으로 변하게 된다. 이렇게 되면 모터의 출력은 직선으로 예측하였을 때 보다 실제적으로 작은 출력이 발생하게 된다. 따라서 일반적으로 DC모터를 설계할 때 T-N특성의 비선형화로 인한 출력의 감소현상을 고려하여 임의의 여유를 주고 설계하여 왔다. 그러나 효율적인 모터설계를 위하여서는 임의의 여유가 아닌, 이론적 계산에 의한 정확한 T-N특성의 곡선을 필요로 하게 된다. 하지만 아직까지 이를 위한 용이한 계산법은 마련되어 있지 않다. 따라서 본 논문에서는 matlab을 이용하여 DC모터의 비선형 T-N곡선의 계산법을 도출하여 그 방법을 제시하고자 한다.

• Journal of Korean Ophthalmic Optics Society
• /
• v.5 no.2
• /
• pp.151-155
• /
• 2000

We calculated a refractive index of the lens surface by measuring a spectral reflectance for a tinted time on manufacturing of the color lens. The longer a tinted time, the larger a reflectance and reflective index. The refractive index increased for a time up to the colorant's saturation state on the lens surface. The refractive index's change curve of blue color lens for a time depended on the Boltzmann growth curve. then we obtained the parameter's values of $n_{min}=1.482$, $n_{max}=1.497$, $t_c=11.53$ and $d_0=2.287$.

• Proceeding of EDISON Challenge
• /
• 2014.03a
• /
• pp.115-125
• /
• 2014

We investigate dissociation of diatomic molecules and anions using density functional theory (DFT) and density-corrected density functional theory (DC-DFT). We scan the potential energy curve of CH, NH and NO neutral molecule and its anion with both DFT and DC-DFT (in form of Hartree-Fock DFT, HF-DFT) using various functionals. Using CCSD(T) results as reference, we perform the error decomposition scheme recently proposed by Kim et al. The results show while most neutrals are $functio{\acute{n}}al$ error $domi{\bar{n}}ating$ normal calculations, $CH^-$ and $NO^-$ anions are density-driven error dominating abnormal calculations. In case of $NH^-$, traditional DFT goes to a wrong dissociation limit indicating abnormality, but both HF-DFT and CCSD(T) results need further investigation due to the kinks on the curve.

• Journal of Korean Society on Water Environment
• /
• v.29 no.6
• /
• pp.762-776
• /
• 2013

Load duration curve was applied to determine important water quality parameter control term for improvement of Paldang lake water quality. Load duration curve was analyzed with long term data from 1985 to 2012 including water quality, flow rate and climate state of Paldang water environment. From the result of flow rate patterns of paldang lake, differences between high and low flow rate of each year showed tendency of increase because rainfall characteristics of paldang lake watershed were changed by climate exchange. Both of land use state of upper Paldang lake watershed and number of limit excess from load duration curve indicated that seasonal action related with land use such as agricultural fertilizer distribution in upper watershed affected Paldang lake water quality. So focused BOD (biological oxygen demand) management during spring season from march to June is required to control organic materials in Paldand lake. The main affecting factor of TOC (total organic carbon) increase in Paldang lake was initial rainfall after march. T-N (total nitrogen) kept increasing during research period, so enhancement of T-N standard is needed to T-N control. Initial rainfall and increase of temperature during spring season from March to June showed a positive correlation with TP (total phosphorus) and Chl-a, respectively.

• Journal of Environmental Science International
• /
• v.28 no.10
• /
• pp.873-885
• /
• 2019

In this study, a load duration curve was applied to the Jangseongcheon, one of the tributaries of the Yeongsan River, to assess whether the target water quality was achieved. In addition, pollution of the water body was investigated to develop and suggest the optimal management time with respect to polluted flow sections and monthly conditions. The average flow rates of sections JS1 and JS2 were $0.25m^3/s$ and $1.08m^3/s$, respectively. The BOD and T-P for water-quality standards at JS1 were rated at II, whereas the COD and TOC were rated at III, thus indicating a fair level of water quality. By contrast, the BOD at JS2 was rated at III, the T-P at IV, and the TOC at V, indicating poor water quality in this section. The load duration curve was plotted using the actual flow data measured in eight-day intervals for eight years from 2011 to 2018 at locations JS1 and JS2 in the Jangsungcheon Basin. In an assessment using the load duration curve on whether the target water quality was met at location JS1, all of the water quality parameters (BOD, COD, TOC, T-N, T-P, and SS) satisfied the target water quality. By contrast, at location JS2, parameters COD, TOC, T-N, and T-P exceeded target values by more than 50%, indicating the target water quality was not met. The discharge loads of locations JS1 and JS2 were analyzed to identify the reasons the target water quality was exceeded. Results revealed that the land system contributed considerably. Furthermore, the discharge load of JS2 accounted for more than 80% of the load on the entire basin, excluding that of JS1. Therefore, the best method for restraining the inflow of pollutants into the stream near location JS2 must be applied to manage the water quality of the Jangsungcheon.

• Journal of Korean Society on Water Environment
• /
• v.26 no.6
• /
• pp.903-909
• /
• 2010

The purpose of this study was evaluated on the applicability of Load Duration Curve Method (LDC Method) using HSPF watershed model and sampling data for efficient TMDLs in Korea. The LDC Method was used for assessment pollutant characteristics in watershed and water quality variation in each water flow level. Load Duration Curve is applied for judge the level of impaired water-body and can be estimated the impaired level by pollutant, such as BOD, T-N, and T-P in this study depending on variation of stream flow. As a result, BOD, T-P was usually exceed the standard value at low flow and dry hydrologic period. Improvement of effluent concentration from WWTP and riparian buffer protection zone are effective to improve the water quality. T-N showed the worst condition at mid-range hydrologic period and moist hydrologic period. Therefore, soil erosion control program and BMPs for non-point source pollution control is effective for recovery the water quality, which can be useful method for management of water quality in the plan of recovery water quality spontaneously. Applicability of LDC Method was evaluated in the Nakbon A watershed. However, we need to consider more detailed and accumulated data set such as accurate GIS data and detail pollution data, and WWTP discharge water quality data for accurate evaluation of watershed. Overall, The LDC Method is adequate for evaluation of watersheds characteristics, and its application is recommended for watershed management and TMDL Implementation.

• Journal of Internet of Things and Convergence
• /
• v.6 no.2
• /
• pp.25-29
• /
• 2020

The elliptic curve crypto-algorithm is widely used in authentication for IoT environment, since it has small key size and low communication overhead compare to the RSA public key algorithm. If the scalar multiplication, a core operation of the elliptic curve crypto-algorithm, is not implemented securely, attackers can find the secret key to use simple power analysis or differential power analysis. In this paper, an elliptic curve scalar multiplication algorithm using a randomized scalar and an elliptic curve point blinding is suggested. It is resistant to power analysis but does not significantly reduce efficiency. Given a random r and an elliptic curve random point R, the elliptic scalar multiplication kP = u(P+R)-vR is calculated by using the regular variant Shamir's double ladder algorithm, where l+20-bit u≡rn+k(modn) and v≡rn-k(modn) using 2^lP=∓cP for the case of the order n=2^l±c.