• Atmosphere
• /
• v.16 no.1
• /
• pp.33-48
• /
• 2006

A classification of snowfall type based on development mechanism is proposed using previous snowfall studies, operational experiences, etc. Five types are proposed: snowfall caused by 1) airmass transformation (AT type), 2) terrain effects in a situation of expanding Siberian High (TE type), 3) precipitation systems associated with extratropical cyclones (EC type), 4) indirect effects of extratropical cyclones passing over the sea to the south of the Korean peninsula (ECS type), and 5) combined effects of TE and ECS types (COM type). Snowfall events during 1981-2001 are classified according to the 5 types mentioned above. For this, 118 events, with at least one station with daily snowfall depth greater than 20 cm, are selected. For the classification, synoptic weather charts, satellite images, and precipitation data are used. For TE and COM types, local sea-level pressure chart is also used to confirm the presence of condition for TE type (this is done for events in 1990 and thereafter). The classification shows that 109 out of 118 events can be classified as one of the 5 types. In the remaining 8 events, heavy snowfall occurred only in Ullung Island. Its occurrence may be due to one or more of the following mechanism: airmass transformation, mesoscale cyclones and/or mesoscale convergence over the East Sea, etc. Each type shows different characteristics in location of snowfall and composition of precipitation (i.e., dry snow, rain, and mixed precipitation). The AT-type snowfall occurs mostly in the west coast, Jeju and Ullung Islands whereas the TE-type snowfall occurs in the East coast especially over the Young Dong area. The ECS-type snowfall occurs mostly over the southern part of the peninsula and some east cost area (sometimes, whole south Korea depending on the location of cyclones). The EC- and COM-type snowfalls occur in wider area, often whole south Korea. Precipitation composition also varies with the type. The AT-type has a snow ratio (SR) higher than the mean value. The TE- and EC-type have SR similar to the mean. The ECS- and COM-type have SR values smaller than the mean. Generally the SR values at high latitude and mountainous areas are higher than those at the other areas. The SR value informs the characteristics of the precipitation composition. An SR value larger than 10 means that all precipitation is composed of snow whereas a zero SR value means that all precipitation is composed of rain.

• Atmosphere
• /
• v.26 no.2
• /
• pp.257-275
• /
• 2016

Asian dust is a seasonal meteorological phenomenon influencing most East Asia, irregularly occurring during spring. Unusual heavy Asian dust event in winter was observed in Seoul, Korea, with up to $1,044{\mu}g\;m^{-3}$ of hourly mean $PM_{10}$, in 22~23 February 2015. Causes of such infrequent event has been studied using both ground based and spaceborne observations, as well as numerical simulations including ECMWF ERA Interim reanalysis, NOAA HYSPLIT backward trajectory analysis, and ADAM2-Haze simulation. Analysis showed that southern Mongolia and northern China, one of the areas for dust origins, had been warm and dry condition, i.e. no snow depth, soil temperature of ${\sim}0^{\circ}C$, and cumulative rainfall of 1 mm in February, along with strong surface winds higher than critical wind speed of $6{\sim}7.5m\;s^{-1}$ during 20~21 February. While Jurihe, China, ($42^{\circ}23^{\prime}56^{{\prime}{\prime}}N$, $112^{\circ}53^{\prime}58^{{\prime}{\prime}}E$) experienced $9,308{\mu}g\;m^{-3}$ of hourly mean surface $PM_{10}$ during the period, the Asian dust had affected the Korean Peninsula within 24 hours traveling through strong north-westerly wind at ~2 km altitude. KMA issued Asian dust alert from 1100 KST on 22nd to 2200 KST on 23rd since above $400{\mu}g\;m^{-3}$ of hourly mean surface $PM_{10}$. It is also important to note that, previously to arrival of the Asian dust, the Korean Peninsula was affected by anthropogenic air pollutants ($NO_3^-$, $SO_4^{2-}$, and $NH_4^+$) originated from the megacities and large industrial areas in northeast China. In addition, this study suggests using various data sets from modeling and observations as well as improving predictability of the ADAM2-Haze model itself, in order to more accurately predict the occurrence and impacts of the Asian dust over the Korean peninsula.

• Clean Technology
• /
• v.19 no.4
• /
• pp.437-445
• /
• 2013

To develop SEWGS (sorption enhanced water gas shift) system using dry $CO_2$ absorbent for pre-combustion $CO_2$ capture, hydrodynamic characteristics of $CO_2$ absorbents were measured and investigated. The minimum fluidization velocity of $CO_2$ absorbent was measured and the effects of the operating conditions were investigated to operate the system at bubbling fluidized bed condition. The minimum fluidization velocity decreased as pressure and temperature increased. Moreover, the minimum fluidization velocity decreased as column diameter increased. The effects of operating conditions on the solid circulation rate were measured and investigated to select appropriate operating conditions for continuous $CO_2$ capture and regeneration. The measured solid circulation rates were ranged between 10 and 65 kg/h and increased as the solid injection velocity, gas velocity in the regeneration reactor, and solid height increased.

• Korean Journal of Weed Science
• /
• v.15 no.3
• /
• pp.175-182
• /
• 1995

The experiment was conducted to obtain basic information on weed ecology and effective weed control in direct-seeded rice Gelds at National Yeongnam Agricultural Experiment Station in 1994. Double cropping system of rice-barley reduced weed occurrence about 30% as compared with rice single cropping due to allelopathic effect of barley residue or stubble. Occurrences of red rice (weedy rice), barnyard grass and water foxtail were closely related with tillage method; the greatest occurred in no tillage plot followed by rotavation only and plow plus rotavation. Period of seed germination of barnyard grass and carbgrass varied with temperature and soil depth. In the same environmental condition, the germination period of barnyard grass shortened 3 to 5 days as compared with that of carbgrass. Two systematic applications of herbicides, that is, the first application at 10 to 15 days after seeding and the second at just after flooding, were the most recommendable system in dry-seeded rice field in terms of weed suppression and yield capacity.

• Journal of Korea Water Resources Association
• /
• v.48 no.10
• /
• pp.857-868
• /
• 2015

Hydraulic and water quality models with high reliability are necessary for the efficient management of water quality in the reservoir. The model capacity can be demonstrated by the application for the various hydrological conditions. CE-QUAL-W2 model is laterally averaged two-dimensional hydraulic and water quality model. The W2 model, which is suitable for the narrow reservoir like the Jinyang reservoir as compared with the depth and length of waterbody, has been frequently used by many researchers. Namgang watershed is expected to increase the water demand. In this study, the W2 model is validated under two different hydrological conditions; wet year (2011) and normal year (2009). Using hydrological and water quality condition for calibration, 2011, the effect of water intake increase was simulated. The simulation results showed that the increase of water intake led to increase the concentrations in total nitrogen, total phosphorus and Chlorophyll-${\alpha}$ concentration. Especially the concentration increase was appeared during the dry season in each of up to 62.53% (Total nitrogen), 39.07% (Total phosphorus) and 232.19% (Chlorophyll-${\alpha}$). The changes of chlorophyll-${\alpha}$ is similar to those of total phosphorus concentration.

• Korean Journal of Medicinal Crop Science
• /
• v.4 no.4
• /
• pp.283-287
• /
• 1996

As a part of studies on the quality control for drying methods in Lycii Fructus. Dried Lycii Fructus were obtained from several treatments to examine the control of the extracts and its physical properties, and also to analyze the inorganic elements and proximate compositions. The results were summerized as follows; the changes of solid matter contents dried at $50^{\circ}C\;for\;4\;hrs\;and\;60^{\circ}C$ for 28 hrs were highest. The changes of Hunter values were 66 in lightness, 5.0 in redness and 51.3 in yellowness, respectively in treatment No. 1. And also the viscosity of treatment No. 1. was some high compared to the other treatment. The desirable drying temperature were at $50^{\circ}C$ for 2hrs in initial and at $60^{\circ}C$ for 24hrs in final temperature and it was the best conditions as a quality, economics and chemical compositions of Lycii Fructus.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.29 no.6
• /
• pp.995-1002
• /
• 2000

In order to Develop a low Na functional kimchi using sea tangle, the Na-binding capacity of alginate in sea tangle along with other dietary fibers was evaluated in vitro. The adding type and amount of the sea tangle that contains alginate in kimhi and characteristics of the sea tangle added kimchi were also studied. Na-binding capacity of various dietary fibers such as cellulose, pectin, gun gum, carageenan, alginates (sodium alginate, alginate, alginate from sea tangle) was measured by equilibrium dialysis method in pH 2 and pH 7 in vitro. Gua gum, carageenan and a group of alginates effectively bound to Na+ Espacially sodium alginate showed high Na-binding capacity of 29.2% in pH of stomach (pH 2.0) and 33.8% in pH of small intestine (pH 7.0), however, the alginate extracted from sea tangle could not bind Na in PH of stomach (pH 2.0), but 27.4% in pH of small intestine (pH 7.0) condition. The content of alginate in sea tangles (dried sea tangle, salted sea tangle and washed salted sea tangle) was 19.8 ~ 22.2% on dry matter basis. The sea tangle added kimchi was prepared with the addition of the flake type (0.5$\times$3 cm) of sea tangle with a quantity of 30% in kimchi from the data of the sensory analysis. The addition of the sea tangle to the kimchi increased the content of soluble dietary fiber, suggesting the Na-binding capacity increased. The sea tangle added kimchi (SK) and sea tangle and fermented anchovy added kimchi (SAK) showed higher levels of reducing sugar and acidity than the control kimchi (CK). In quantitative descriptive analysis (QDA) SK and SAK showed higher score in overall acceptance, and lower score in acidic order than CK, however, SK showed less moldy taste and more fresh acidic taste than SAK.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.19 no.6
• /
• pp.617-624
• /
• 1990

Proper processing condition of Yukwa(oil popped rice snack) for mass production and pop-ping mechanism of it were tested with Shinsun (waxy, Japonica type rice) which was excellent for Yukwa making. Optimum steaming time of dough was 15 min among 4 to 60 min and reasonable moisture content of the dough before steaming was 4895 among 48 to 53% which had good and fine texture. Acceptable stirring time of steamed dough was not significantly different among 1 to 4 min, but no stirring with much larger volume was shown very poor and too soft in texture. At the simplification test of milling method, wet milling was better then dry milling in expansion rate and high temperature treatment of dough at 6$0^{\circ}C$ gave negative effect on their quality. Extending high temperature treatment of dough, reducing sugars in the dough increased and it might be caused of starch degradation. In addition of some other protein sources to dough, Yukwa quality were in proportion to the protein content of the beans. At the long term storage of the Yukwa base, moisture absorption was different depending upon RH of atmosphere and the quality of Yukwa was inferior by storage time. By addition of some alcoholic beverage, such as Makkoli, Soju and Chungju, expansion rate and their texture were somewhat improved by increasing addition amount of them from 15% to. 30％ on dough (w/w).

• Journal of Convergence for Information Technology
• /
• v.10 no.7
• /
• pp.153-159
• /
• 2020

In order to find out the condition of flow in sewer pipes, this study investigated the characteristics of tractive force of sewage flow estimated using actual measured values of water level, velocity, and flowrate in sewers located at uppermost portion in a treatment area during dry weather periods. When the scene of sewage flow was taken by CCTV after cohesive and non-cohesive solids (tofu and sand) were put on the sewer invert, it was found that the solids could be flushed without significant interruption. In sewer with slope of 0.00319, the frequency exceeding the minimum tractive force of sewage during a weekday was zero, while it was 10 per day with slope of 0.00603. During the week of the field observation, the event to exceed the minimum tractive force occurred once, suggesting that sewer odor would potentially increase. Maximum tractive force in sewer with steep slope was 2.9-3.1 N/㎡, but with gentle slope it decreased to 1.6-1.7N/㎡. It was also observed that the interval of time maintained below the criterion of minimum tractive force increased, during weekends compared to weekdays and for the sewage including non-cohesive particles which could enter combined sewers during a storm period. This study found that the sewer sediments formed by direct feces input into sewers, through sewer pipes which were designed meeting the standard sewer design criteria, could be flushed without staying as deposited solids state for a long time.

• Journal of Korea Water Resources Association
• /
• v.49 no.9
• /
• pp.799-807
• /
• 2016

The aim of this study is to determine and propose the by-pass rainwater sewer system in order to reduce the urban floodplain from the locality heavy rain every year during the dry season and the sinkholes in the city as well as the shortage of groundwaters due to extreme hot weather condition and urban heat island phenomenon. Heavy rain occurs more than the years of heavy rainfall probability, comparison between the place where uses the existing pipes and connect the sewer system with by-pass rain permeability and without expanding sewer pipe replacement at intersection of Gangnam station 3.07 ha at Gangnam-gu, Seoul Metropolitan area, it indicates that average of 27 million KRW (44%) maintenance cost savings and maintain existing sewer system without any other countermeasures. For the city flooded reduction, by-pass rainwater permeable rainwater pipe multiplying the probability the number of years during summer season and increase the water flow capacity during spring and fall when a small amount of rain that, it also contribute to the total amount of underground water secured through the by-pass penetration.