• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.1
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• pp.13-18
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• 1976

1) The variation of the reef knot strength $T_r$ and the trawler knot strength $T_\varrho$ with the angle $\varphi$ between the adjacent bars are given by $$T_r=T_{ro}-k_{r\varphi}$$ and $$T_\varrho=T_{{\varrho}o}+k_{\varrho\varphi}$$ where $T_{ro}$ and $T_{{\varrho}o}$ are values of $T_r$ and $T_\varrho$ at $\varphi=0^{\circ}$ respectively, and $k_r$ and $k_\varrho$ constants decided by the fibre materials of netting twines ($\varphi\;is\;0^{\circ}$ when the knot is pulled lengthwise). 2) The variation of the reef knot strength $T_r'$ and the trawler knot strength $T_\varrho'$ with the angle $\varphi'$ between any one bar and the plane made by the other three bars may be expressed by $$T_r'=T_{ro}{'}\varrho^{-c\varphi'}$$ and $$T_\varrho'=T_{{\varrho}o}{'}\varrho^{-c\varphi'}$$ where $T_{ro}{'}$ and $T_{\varrho}o{'}$ are values of $T_r{'}$ and $T_\varrho{'}$ at $\varphi'=0^{\circ}\;{(\varphi=45^{\circ})}$ respectively, and o is the coefficient of attenuation. 3) Knot strength of knotted netting may be expressed by the expression derived in the preyious paper, disregarding its shape and the direction of tensile loads acting on it.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.6
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• pp.518-524
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• 1990

Actual evapotranspiration was measured over rice paddy field by Bowen ratio heat balance method and based on this, investigated was the reliability of actual evapotranpiration estimation from Class-A Pan and small pan evaporation and reference evapotranspiration calculated by modified Penman-Monteith model. Crop coefficients based on Class-A Pan and small pan evaporation and reference evapotranspiration by modified Penman-Monteith model were averaged to be 1.57. 1.10 and 1.49 over the whole rice growing season, respectively. Their respective coefficients of variation were 28.7. 22.7 and 12.8 percent, respectively. Crop coefficient based on modified Penman-Monteith model varied in good agreement with the trend of leaf area development, being greatest around heading stage.

• Korean Journal of Food Science and Technology
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• v.17 no.2
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• pp.107-112
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• 1985

Viscometric properties of japonica(Olchal) and japonica${\times}$indica(Hankang and Suwon 317) waxy rice starches were investigated. Light transmittance of starch suspension increased from $50^{\circ}{\sim}55^{\circ}C$ and remained constant after $75^{\circ}C$. Swelling power was in the order of Hankang, Suwon 317 and Olchal. Amylograph data revealed that Hankang had the highest viscosity at all reference points. The apparent viscosity of 5% starch suspension indicated that the j${\times}$indica starches were completely gelatinized after 30 min cooking at $65^{\circ}C$ whereas japonica starch at $70^{\circ}C$. The apparent viscosity of gelatinized starch at $121^{\circ}C$(15 psig) was higher compared to that of gelatinized one at $95^{\circ}C$. Hankang was the most susceptable to alkali gelatinization followed by Suwon 317 and Olchal.

• Journal of Korean Society of Transportation
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• v.28 no.5
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• pp.141-153
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• 2010

The study is about the development of operating speed prediction models aimed for an evaluation of design consistency of four lane rural roads. The main differences of this study relative to previous research are the method of data collection and classification of road alignments. The previous studies collected speed data at several points in the horizontal curve and approaching tangent. This method of collection is based on the assumption that acceleration and deceleration only occurs at horizontal tangents and the speed is kept constant at horizontal curves. However, this assumption leads to an unreliable speed estimation, so drivers' behavior is not well represented. Contrary to the previous approach, speed data were collected with one and data analysis using a speed profile is made for data selection before building final models. A total of six speed prediction models were made according to the combination of horizontal and vertical alignments. The study predicts that the speed data analysis and selection for model building employed in this study can improve the prediction accuracy of models and be useful to analyze drivers' speed behavior in a more detailed way. Furthermore, it is expected that the operating speed prediction models can help complement the current design-speed-based guidelines, so more benefits to drivers as real road users, rather than engineers or decision makers, can be achieved.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.132-132
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• 2012

압력 $10^{-9}$ Torr 이하의 초고진공(ultrahigh vacuum) 영역에서의 압력 측정에는 수 mA의 열전자로 잔류 가스를 이온화시켜 그 이온 전류를 측정하는 이온게이지를 주로 사용한다. 압력이 $10^{-12}$ Torr영역 이하인 극고진공(extreme high vacuum: XHV) 영역에 진입하면, ESD (electron stimulated desorption) 효과 등에 의한 이온 게이지 자체의 가스방출률이 커져 정확한 압력 측정이 곤란해 진다. 극고진공 영역에서 이온 게이지는 수 와트(W) 이상의 전력을 사용하여 수 mA의 열전자를 방출시키나, 신호인 이온 전류의 양은 1pA 이하이기 때문에 열전자에 의해 발생되는 백그라운드 전류에 묻혀 신호 전류가 측정되지 않는다고 할 수 있다. 100 nm 이하의 곡률을 가진 뾰족한 금속 탐침에 강한 전기장을 걸어주면 고체 내부의 전자가 터널링 효과에 의해 진공 중으로 방출되며, 이를 전계방출(Field Electron Emission) 효과라 부른다. 전계 방출 전류량은 탐침 표면의 일함수에 의존하며, 일함수가 클수록 지수함수 적으로 감소한다. 금속 표면에 진공 중의 잔류 가스가 부착하면 일함수가 증가한다. 가열에 의해 전계방출 탐침의 표면을 세정한 후에 전자 빔을 방출 시키면, 표면에 가스 분자가 흡착하여 방출 전류량은 점점 감소한다. 감소 속도는 압력에 비례하며, W(310) 탐침의 경우 $10^{-10}$ Torr 영역에서는 수분만에 최초 전류값의 1% 이하로 감소한다. 전계방출 전류의 감소속도가 압력에 비례하는 현상을 이용하여 압력을 측정하였다. Extractor Ionization Gauge 측정값 $5{\times}10^{-12}-3{\times}10^{-10}$ Torr의 범위에서 (111) 방향으로 정렬된 텅스텐 단결정 탐침을 사용하여 방출전류의 로그값을 시간의 함수로 semilog그래프를 그리면, 그래프는 직선을 그리며 그 기울기가 압력에 비례함을 알 수 있었다. 기울기 값과 게이지 측정값은 $10^{-11}{\sim}10^{-10}$ Torr 영역에서 거의 완벽한 비례관계를 보여주었으나, $10^{-12}$ Torr 영역에서 게이지 측정값은 기울기 값에서 추출한 압력치보다 높은 값을 보여주었으며, 이는 게이지 백그라운드 전류에 의한 차이라고 생각된다. W (310) 탐침의 방출전류는 그 감소속도가 W (111) 탐침과 마찬가지로 압력에 비례하였으나, 전류-시간 그래프는 가열 세정 직후에 전류가 거의 감소하지 않는 $2{\times}10^{-10}$ Torr에서 약 10분간 지속되는 '안정 영역'이 존재함을 보여주었다. '안정 영역'은 $10^{-11}$ Torr 영역에서는 수십분, $10^{-12}$ Torr 영역에서는 수시간 이상으로 증가하였다. 초-극고진공 영역에서의 잔류가스 주성분인 수소에서 물, 일산화탄소등의 가스로 바뀌면 '안정 영역'은 사라졌고, 이는 '안정 영역'이 수소 흡착에 의해서만 나타나는 고유 현상임을 말해준다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.21 no.2
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• pp.250-257
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• 1976

Defoliation effect of two soybean cultivars on the grain yield was studied under different planting densities planted at two different planting date. Leaf removal caused a linear decrease of grain yield with increased amounts of defoliation in the case of lower population densities, while in the case of higher population densities over 40 plants per sqare meter, the slight removal of lower leaves indicated increased grain yields by 13% to 35% compared with control depending on the cultivar and planting time. The pod number per plant was the most effective factor influencing grain yield. The grain weight and the percent of matured grain become more important components for higher yield with decreased population densities depending on cultivar.

• Korean Journal of Materials Research
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• v.3 no.4
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• pp.327-335
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• 1993

Using a RF cylindrical magnetron operated with two electromagnets having a Helmholz configuration, RF magnetron plasma properties and characteristics of reactive ion ething of Si were investigated as a function of applied magnetic field strengths using 3mTorr $CF_4/H_2$ and $CHF_3$. Also, I-V characteristics of Schottky diodes, which were made of silicons etched under different applied magnetic field strengths and gas environments, were measured to investigate the degree of radiation damage during the reactive ion etching. As the magnetic field strent;th increased, ion densities and radical densities of the plasmas were increased linearly, however, the dc self-bias voltages induced on the powered electrode, where the specimen are located, were decreased exponentially. Maximum etch rates, which were 5 times faster than that etched without applied magnetic filed, were obtained using near lOOGauss, and, under these conditions, little or no radiation damages on the etched silicons were found.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.9
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• pp.505-510
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• 2015

This study investigated formation potential of 16 disinfection byproducts (DBPs) (e.g., g trihalomethanes, haloacetic acids, haloacetonitriles, chloral hydrate, etc.) upon chlorination of raw water at various pH, water temperatures, and chlorine doses. We also compared the DBP formation potential (DBPFP) of raw and filtered waters. Most of DBPs were formed higher at neutral pH, but dichloroacetic acid, chloroform, and bromodichloromethane were formed higher over pH 7. As water temperature increased, concentrations of chloral hydrate, haloacetic acids, and haloacetonitriles linearly increased while that of trihalomethanes exponentially increased. Formation of chloral hydrate, trihalomethanes, and trihaloacetonitriles significantly increased up to 2.0 mg/L $Cl_2$ of chlorine addition, then gradually increased at 2.0~5.6 mg/L $Cl_2$. Filtered water formed less DBPs than raw water in most DBPs except for trihalomethanes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.3
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• pp.154-160
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• 1970

The present paper deals with the growth of yellow croaker by scale age reading. This study is based on material from 596 specimens caught by the Danish seine in the Yellow Sea during the period from June 1967 to April 1968. Ring marks of the scale were formed from April to July, corresponding to the spawning season of the fish reported by Bae (1960). Growth rate of each radius of the ring was approximately 0.73. The relationship between the total length and radius of scales, and the relationship between the body weight and total length are represented by the following equations respectively: L=61.350R+50.184 $$W=4.298L^{3.227}\times10^{-3}$$ Maximum total length calculated by the diagram of Walford's growth transformation, $$L_{n+1}=0.6866L_n+10.8730$$, was 346.9mm. Growth curve of the fish can be expressed by the following von Bertalanffy's equation : $$L_t=346.9(1-e^{-0.376(t+0.609)})$$

• Korean Journal of Construction Engineering and Management
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• v.21 no.1
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• pp.21-31
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• 2020

Recently, interest and financial investment in community infrastructure have been growing. Accordingly, Korean Ministry of Land, Infrastructure and Transport suggested a standard for community infrastructure planning. The standard was based on time distance which represents citizens' accessibility to infrastructure facilities. This paper presents a method to use the navigation application programming interface (API) to calculate travel time. Buffer analysis using Euclidean distance has been widely used so far to evaluate accessibility. However, this method has limitation in that it does not reflect situations in the real world such as crosswalks and slope ways. The infrastructure accessibility indices of local towns in Yeonsu-gu, Incheon were computed based on the time obtained by navigation API. Also, Yeonsu-gu was spatially analyzed to reveal the resident units that are marginalized from community infrastructure facilities. Using navigation API enables to compute realistic accessibility indices and to find unbenefitted residential areas. The method presented in this paper can help community infrastructure planners for their facility spatial plan and budget distribution.