• Title/Summary/Keyword: Annual change

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Characteristics in Chemical Properties of Agricultural Groundwater in Gyeongnam Province (경남지역 농업용 지하수의 수질특성)

  • Lee, Seong-Tae;Kim, Eun-Seok;Song, Won-Doo;Kim, Jin-Ho;Kim, Min-Kyeong;Lee, Young-Han
    • Korean Journal of Soil Science and Fertilizer
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    • v.45 no.5
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    • pp.698-703
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    • 2012
  • This survey was conducted to obtain basic data of the quality of groundwater for agriculture in Gyeongnam province. Groundwater samples from paddy 15, upland 15, and plastic film house 30 sites were collected on April, July, and October in every two years from 2002 to 2008. According to the result of water quality analysis, groundwater quality was suitable for irrigation purpose averagely. The $NO_3$-N contents by land use were in the order of plastic film house > upland > paddy field and its contents were 6.53, 4.80, and $3.68mg\;L^{-1}$, respectively. In annual changes of water quality, pH was no significant change in paddy, upland, and plastic film house by 6.6~6.9. EC was increased in upland and plastic film house in 2008 and majors factors were $NO_3$-N and $Cl^-$. In upland and plastic film house, $NO_3$-N contents were 4.72 and $6.52mg\;L^{-1}$ in 2002, respectively, whereas they were 5.63 and $8.70mg\;L^{-1}$ in 2008, respectively. Of the investigated sites, $NO_3$-N was exceeded water quality standards for agriculture by 3.3~15.0% in plastic film house and $Cl^-$ was exceeded water quality standards for agriculture by 2.2% in upland of 2004. The $NO_3$-N contents were decreased with well depth and their contents were $5.38mg\;L^{-1}$ from 3~10 m, $4.87mg\;L^{-1}$ from 10~20 m, and $2.58mg\;L^{-1}$ from above 30 m. The $NO_3$-N contents by soil texture were highest in sandy loam by $5.73mg\;L^{-1}$ and lowest in clay loam by $4.13mg\;L^{-1}$. The $NO_3$-N contents by crops category were in order of fruit vegetables > leaf vegetables > rice > fruits > beans, contents of fruit vegetables and leaf vegetables were 5.81 and $5.30mg\;L^{-1}$, respectively.

Estimation and assessment of baseflow at an ungauged watershed according to landuse change (토지이용변화에 따른 미계측 유역의 기저유출량 산정 및 평가)

  • Lee, Ji Min;Shin, Yongchun;Park, Youn Shik;Kum, Donghyuk;Lim, Kyoung Jae;Lee, Seung Oh;Kim, Hungsoo;Jung, Younghun
    • Journal of Wetlands Research
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    • v.16 no.4
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    • pp.303-318
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    • 2014
  • Baseflow gives a significant contribution to stream function in the regions where climatic characteristics are seasonally distinct. In this regard, variable baseflow can make it difficult to maintain a stable water supply, as well as causing disruption to the stream ecosystem. Changes in land use can affect both the direct flow and baseflow of a stream, and consequently, most other components of the hydrologic cycle. Baseflow estimation depends on the observed streamflow in gauge watersheds, but accurate predictions of streamflow through modeling can be useful in determining baseflow data for ungauged watersheds. Accordingly, the objectives of this study are to 1) improve predictions of SWAT by applying the alpha factor estimated using RECESS for calibration; 2) estimate baseflow in an ungauged watershed using the WHAT system; and 3) evaluate the effects of changes in land use on baseflow characteristics. These objectives were implemented in the Gapcheon watershed, as an ungauged watershed in South Korea. The results show that the alpha factor estimated using RECESS in SWAT calibration improves the prediction for streamflow, and, in particular, recessions in the baseflow. Also, the changes in land use in the Gapcheon watershed leads to no significant difference in annual baseflow between comparable periods, regardless of precipitation, but does lead to differences in the seasonal characteristics observed for the temporal distribution of baseflow. Therefore, the Guem River, into which the stream from the Gapcheon watershed flows, requires strategic seasonal variability predictions of baseflow due to changes in land use within the region.

The Effects of Female Wage on Fertility in Korea (여성의 임금수준이 출산율에 미치는 영향 분석)

  • Kim, Jungho
    • KDI Journal of Economic Policy
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    • v.31 no.1
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    • pp.105-138
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    • 2009
  • Although the decline in fertility rate is generally observed along the history of economic development throughout the world, the continuing decline hitting below the replacement level in Korea over the recent years gathered serious social concerns on the ground that it accelerates the process of population aging. The total fertility rate in Koreareached 2.08 in 1983, and gradually fell to the levels of 1.08 in 2005 and 1.26 in 2007. The policy debate over the role of the government has been focused mainly on the level of theoretical discussion without substantial basis on firm empirical evidence and the determinants of fertility. The objective of the paper is to empirically investigate the fertility effect of the female wage, which is understood as one of the most important determinants of fertility in Koreasince 1980 focusing on one aspect of fertility, namely birth spacing. Using the Korean National Fertility Survey conducted in 2006, I estimate a duration model of first and second births taking into account individual heterogeneity, which turned out to be an important factor to control for. Compared with previous studies in the literature on the Korean fertility, the study has an advantage of using the complete pregnancy history of women in a more representative sample. Unlike the previous studies, the analysis also deals with the endogeneity of marriage by treating a certain age, rather than age at marriage, as the time in which a woman becomes exposed to the risk of pregnancy. The study shares the common problem in the literature on birth spacing of lacking relevant wage information for respondents in a retrospective survey. I estimate the wage series as a function of the basic characteristics using the annual Wage Structure Survey from 1980 to 2005, which is considered as a nationally representative sample for wage information of employees. The results suggest that the increase in female wage by 10 percent leads to a decrease in second birth hazard by 0.56~0.92 percentage points and that the increase in spouse's wage by the equal amount is accompanied by the increase in second birth hazard by 0.36~1.13 percentage points. These estimates are more precisely estimated and of smaller magnitude than those presented by the previous studies. The results are robust to the different specifications of the wage equation. The simulation analysis based on the predicted values shows that about 17% of the change in the second birth hazard over the period 1980 to 2005 was due to the change in the female wage. Although there is some limitation in data, the results can be viewed as one estimate of the role of female wage on the recent fertility decline in Korea. The question raised by the paper is not a normative one of whether a government should promote childbearing but a positive one thatexplains fertility decline. Therefore, if there is a wide consensus on promoting childbearing, the finding suggests that the policies designed to reduce the opportunity cost of women in the labor market would be effective. The recent movement of implementing a wide range of family-friendly policies including child care support, maternity leave, parental leave and tax benefit in developed countries should be understood in this context.

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The Physico-chemical Characteristics in the Garorim Bay, Korea (가로림만의 이화학적 수질의 시.공간적 특성)

  • Nam, Hyun-Jun;Heo, Seung;Park, Seung-Yun;Hwang, Un-Ki;Park, Jong-Soo;Lee, Hae-Kwang
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.18 no.2
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    • pp.101-114
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    • 2012
  • The physico-chemical characteristics including water temperature, salinity, dissolved oxygen(DO), chemical oxygen demand (COD), chlorophyll-a(Chl. a), suspended particulate matter(SPM) and dissolved inorganic nutrients were investigated in the Garolim Bay, Yellow Sea, Korea in 2010 carried out six times per year at 11 fixed stations by Korea Fisheries Research & Development Institute. The water temperature, salinity, COD, dissolved inorganic nutrients, Chl. a and SPM showed significant difference between surface and bottom water but the other parameters didn't. There were not significant difference between stations. The water temperature showed typical change patterns of the temperate seawater. The annual average of salinity showed more than 31 so that there could not have occurred low saline water. The average of DO from June to August showed over than 3mg/L which showed higher than the below standard value of the hypoxic (oxygen-deficient) water. The average of Chl. a varied $1.68{\mu}g/L$ at surface, $2.38{\mu}g/L$ at bottom layer in June and $1.68{\mu}g/L$ at surface, $1.57{\mu}g/L$ at bottom layer at August. The dissolved inorganic nutrients showed high concentration in February and low concentration in August due to the limitation of the freshwater input in summer and phytoplankton used to the dissolved inorganic nutrients. The ratio of DIN/DIP showed 30.52 at surface and 37.89 at bottom layer in June which was higher than other month. The SPM was 44.15mg/L at bottom layer in February which was the highest value in this study due to the northwest monsoon. Because of the actively water change in the open sea without inflow of freshwater from land in Garolom Bay, there were not occurred low saline water and hypoxic water. thus, this Bay showed good water quality and required to be conserved continuously as important costal area for fisheries.

Bias Correction for GCM Long-term Prediction using Nonstationary Quantile Mapping (비정상성 분위사상법을 이용한 GCM 장기예측 편차보정)

  • Moon, Soojin;Kim, Jungjoong;Kang, Boosik
    • Journal of Korea Water Resources Association
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    • v.46 no.8
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    • pp.833-842
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    • 2013
  • The quantile mapping is utilized to reproduce reliable GCM(Global Climate Model) data by correct systematic biases included in the original data set. This scheme, in general, projects the Cumulative Distribution Function (CDF) of the underlying data set into the target CDF assuming that parameters of target distribution function is stationary. Therefore, the application of stationary quantile mapping for nonstationary long-term time series data of future precipitation scenario computed by GCM can show biased projection. In this research the Nonstationary Quantile Mapping (NSQM) scheme was suggested for bias correction of nonstationary long-term time series data. The proposed scheme uses the statistical parameters with nonstationary long-term trends. The Gamma distribution was assumed for the object and target probability distribution. As the climate change scenario, the 20C3M(baseline scenario) and SRES A2 scenario (projection scenario) of CGCM3.1/T63 model from CCCma (Canadian Centre for Climate modeling and analysis) were utilized. The precipitation data were collected from 10 rain gauge stations in the Han-river basin. In order to consider seasonal characteristics, the study was performed separately for the flood (June~October) and nonflood (November~May) seasons. The periods for baseline and projection scenario were set as 1973~2000 and 2011~2100, respectively. This study evaluated the performance of NSQM by experimenting various ways of setting parameters of target distribution. The projection scenarios were shown for 3 different periods of FF scenario (Foreseeable Future Scenario, 2011~2040 yr), MF scenario (Mid-term Future Scenario, 2041~2070 yr), LF scenario (Long-term Future Scenario, 2071~2100 yr). The trend test for the annual precipitation projection using NSQM shows 330.1 mm (25.2%), 564.5 mm (43.1%), and 634.3 mm (48.5%) increase for FF, MF, and LF scenarios, respectively. The application of stationary scheme shows overestimated projection for FF scenario and underestimated projection for LF scenario. This problem could be improved by applying nonstationary quantile mapping.

Freeze Risk Assessment for Three Major Peach Growing Areas under the Future Climate Projected by RCP8.5 Emission Scenario (신 기후변화시나리오 RCP 8.5에 근거한 복숭아 주산지 세 곳의 동해위험도 평가)

  • Kim, Soo-Ock;Kim, Dae-Jun;Kim, Jin-Hee;Yun, Jin-I.
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.14 no.3
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    • pp.124-131
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    • 2012
  • This study was carried out to evaluate a possible change in freeze risk for 'Changhowon Hwangdo' peach buds in three major peach growing areas under the future climate projected by RCP8.5 emission scenario. Mean values of the monthly temperature data for the present decade (2000s) and the future decades (2020s, 2050s, 2080s) were extracted for farm lands in Icheon, Chungju, and Yeongcheon-Gyeongsan region at 1km resolution and 30 sets of daily temperature data were generated randomly by a stochastic process for each decade. The daily data were used to calculate a thermal time-based dormancy depth index which is closely related to the cold tolerance of peach buds. Combined with daily minimum temperature, dormancy depth can be used to estimate the potential risk of freezing damage on peach buds. When the freeze risk was calculated daily for the winter period (from 1 November to 15 March) in the present decade, Icheon and Chungju regions had high values across the whole period, but Yeongcheon-Gyeongsan regions had low values from mid-December to the end of January. In the future decades, the frequency of freezing damage would be reduced in all 3 regions and the reduction rate could be as high as 75 to 90% by 2080's. However, the severe class risk (over 80% damage) will not disappear in the future and most occurrences will be limited to December to early January according to the calculation. This phenomenon might be explained by shortened cold hardiness period caused by winter warming as well as sudden cold waves resulting from the higher inter-annual climate variability projected by the RCP8.5 scenario.

Ecophysiological Interpretations on the Water Relations Parameters of Trees(IX) - Measurement of the Transpiration Rate by the Heat Pulse Method in a Quercus mongolica Stand - (수목(樹木)의 수분특성(水分特性)에 관(關)한 생리(生理)·생태학적(生態學的) 해석(解析)(IX) - Heat pulse법(法)을 이용(利用)한 신갈나무임분(林分)의 증산속도(蒸散速度) 측정(測定) -)

  • Han, Sang Sup;Kim, Sun Hee
    • Journal of Korean Society of Forest Science
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    • v.85 no.2
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    • pp.288-299
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    • 1996
  • This is the basic study to investigate the amount of transpirational water loss in thrifty mature Quercus mongolica stand by the heat pulse method. The differences of heat pulse velocity by direction and depth, differences of heat pulse velocity by dominant, codominant and suppressed trees, diurnal changes of heat pulse velocity due to the change of leaf water potential, vapor pressure deficit and radiation, and sap flow path way in sapwood by dye penetration were measured in stems. Finally the amounts of daily and annual transpiration in stand were calculated by the heat pulse velocity. The results obtained were summarized as follows : 1. Relationship between heat pulse velocity(V) and sap flow rate(SFR) was obtained as a equation of SFR=1.37V. 2. The sap flow rate was high in the order of dominant, codominant, and suppressed trees. The daily heat pulse velocity changed with radiation, temperature and vapor pressure deficit. 3. The heat pulse velocity showed the similar diurnal variation as the leaf water potential change. 4. The heat pulse velocity showed the highest value in May(4.0cm/hr in average), the lowest one in July(2.9cm/hr in average). 5. The heat pulse velocity in the same stem presented the highest value in the northern direction, medium in western, and the lowest in southern and eastern. 6. The heat pulse velocity in stem was highest in 0.5cm, medium in 1.0cm, and lowest in 1.5cm depth from the surface of stem. 7. The sap flow path way in stem showed sectorial straight ascent pattern in four sample trees. 8. The amount of sap flow(SF) was presented as a equation of $SF=1.37A{\cdot}V$(A: the cross-sectional area of sapwood, V: heat pulse velocity), and especially SF was larger in dominant tree than codominant and suppressed trees. 9. The amount of daily transpiration was 5.6ton/ha/day, and its composition ratio was 72% at day and 28% at night. 10. The amount of stand transpiration per month was largest in May(168ton/ha/month), lowest in July(125ton/ha/month). The amount of stand transpiration per year was 839ton/ha/year.

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A Study of Technical Development of Mariculture in the Coastal Water (천해양식어업발달과정에 관한 연구 - 기술개발활동을 중심으로 -)

  • Choi, Jeang-Yoon
    • The Journal of Fisheries Business Administration
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    • v.16 no.1
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    • pp.91-124
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    • 1985
  • Mariculture is contrasted with inland aqua-culturing fisheries. It is defind as the Industry of rearing Aquaorganism in limited coastal area relatively shallow in depth. Then, It's coming into being realization of Mariculture in it is long in history that Mariculture was realized in Korea. But it is from the early part of 1960s, that this industry has normally developed. Owing to 200 miles economy-zone problems of coastal countries, the development of deep sea fishing was limited, so the Korean Government has now appreciated the importance of cultured industries in the field of coastal fisheries. And the Korean Mariculture the output of which was only 18, 000 M/T in '60s attained 540, 000M/T in 1980s, has now occupied its relative importance in Korean Fisheries Industry. So the purpose of this report is to suggest the prospect of technical development of mariculture in the future of Korea, through the analysis of the various problems that affect upon the individual management '||'&'||' fishing ground utilization, along with the appreciation of "how to extend of those technical innovation" and "how the fishermen's technique level is extended at this stage. According to this study, the result is summarized as follows. First, Maricultural technique is classified into 8 sub-techniques as follows, as shown in fig. 1.Fig. 1. The Formation structure of mariculture technique Second, the change of technical method of mariculture in coastal area of Korea has made as 5 stages; 1) Scattering of culturing organism 2) Culturing by putting stone and installing bamboo 3) Culturing by installing rope and seeding 4) Culturing of putting objectives in cages 5) Culturing fish by feed Third, the maricultural fisheries of Korea has about 70 years long in history. It began from 1910s. But at that time there was no special technique in aquaculture and its technique was confined in searching out the object of species. The species was laver, oyster ect.Forth, although realization of mariculture in Korea has been long time, it is of late from 1960s that this has been industrial with normal development, and its technique of mariculture has mainly has developed from 1970s. Its result not only contributed to the high growth in Korean ecconomy along with the well balanced development between industires, but also it played a great role for the resolution of nation's food problem. Especially maricultural production has shown its sustained annual increase of 13.8% during the last 20 years. So the portion of mariculture among total fisheries stucture was extended from 4.1% in the early 1960s to 22.4% in 1980s.Fifth, it could be safely said that such development in maricultural field is resulted from the activity of aquacultural institutes such as Fisheries Reseach '||'&'||' Development production of major kinds such as Oyster, Sea-mustard, and Laver etc. As well as in the innovation of aquaculturing method with synthetic fiber utilization. FRDA has played important role in the efficient propargation of new aquacultural technique.Sixth, as for the change in aquaculture structure and its during period between 1970s and 1980s, the private management participation shown 25% increase from household number of 45, 173 to 56, 268 in total number. And in the respect of the management scale, of their management decreased, while it showed an increase in relative large scale management, the increase over 3 employees compared with other fisheries field between '70s and 80s. This must be an major trait to be recorded, Now the data above mentioned are shown as in table 1 and 2.Table 1. The maricultural fishing ground development situation in 982.Table 2. The mariculture management as seen in the employmnet size in high seasion.Owing to the technical innovation, of the mariculture in coastal area new income of fishermen increased and it also is true that the number of fishermen participating in its industrialization increased. But the problem being from now on is the self-discharge of the destruction fishing ground considered resulted from rapid expansion in aquaculture industry and the preventive system of sentility of fishing ground. sentility of fishing ground.

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Seasonal Variation of Some Substances in Chestnut Shoots (밤나무 품종별(品種別) 함유성분(含有成分)의 시기적(時期的) 변화(變化))

  • Wi, Heub
    • Journal of Korean Society of Forest Science
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    • v.32 no.1
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    • pp.21-28
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    • 1976
  • This paper reports on seasonal variation of tannin, catechol tannin, pyrogallol tannin, sugar, starch and protein contained in new shoots of four races of Castanea crenata in relation to their resistance to gall-wasps. The four races were Ginyose, Shimokatsugi, Taisyo-wase and Tsuguba. 1. Tannin contents showed the lowest level during June and September, and they gradually increased afterwards. Generally tannin contents were higher in gall-wasp resistant races than in its susceptible races. Mean annual tannin contents were 0.73%, 0.845%, 0.507%, and 0.520%, respectively, in Tsuguba, Ginyose, Shimokatsugi and Taisyo-wase. 2. Catechol tannin contents did not change from February to October, however, increased after that period. Catechol tannin contents in gall-wasp resistant races (Tsuguba and Ginyose) more than doubled those in the susceptible races (Shimokatsugi and Taisyo-wase) all the year round, indicating that there may be a correlation between quantitative differences in catechol tannin and the resistance to gall-wasps. 3. Pyrogallol tannin contents were rather lower in the gall-wasp resistant races than in the susceptible races on the contrary to the above results. 4. Seasonal variation of sugar contents showed similar tendency with catechol tannin. Gall-wasp resistant races contained higher sugar contents than those susceptible races. 5. Starch contents were significantly higher during dormant period. Gall-wasp susceptible races showed higher starch contents than the resistant races did, however, this tendency varied with season. 6. There were not significant differences in protein between races but there was a tendency of higher protein in gall-wasp susceptible races. The seasonal change of protein was similar to that of starch. 7. From the above results it seems that seasonal variation of contents of tannin, catechol and pyrogallol tannin, sugar, starch and protein in new shoots of chestnut trees have some relation to their resistance to gall-wasp.

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Technology for Improving the Uniformity of the Environment in the Oyster Mushroom Cultivation House by using Multi-layered Shelves (느타리버섯 균상재배사의 환경균일성 향상을 위한 기술 개발)

  • Lee, Sunghyoun;Yu, Byeongkee;Kim, Hyuckjoo;Yun, Namkyu;Jung, Jongcheon
    • Journal of Bio-Environment Control
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    • v.24 no.2
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    • pp.128-133
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    • 2015
  • Mushrooms can grow in nature when adequate temperature and humidity are maintained, but such condition can be satisfied for only a short period of time on an annual continuum. Therefore, it can be deemed that a majority of the distributed mushrooms in the current market are produced in an artificially manipulated environment. This study was conducted to resolve the problem of the Oyster mushroom cultivation house's internal temperature and humidity imbalance, where the Oyster mushrooms are cultivated in a multi-layered shelves. The air circulation fans were installed to improve the air uniformity of the Oyster mushroom cultivation house by using multi-layered shelves. During the experiment, the ambient temperature and the ambient relative humidity ranged from $5.2^{\circ}C$ to $20.4^{\circ}C$ and 40% to 100% respectively. Due to the change of the outdoor temperature, the internal temperature of the Oyster mushroom cultivation house also changed, ranging from $13.3^{\circ}C$ to $18.4^{\circ}C$, but the temperature gap between the different internal location of the facility during the conforming recorded time only ranged from $0.2^{\circ}C$ to $1.3^{\circ}C$, being significantly stable. The internal relative humidity, ranging from 82% to 96%, also changed due to the change of the outdoor temperature. Nevertheless, the relative humidity gap between the different internal location during the conforming recorded time only ranged from 2% to 7%. Furthermore, the research staff were able to maintain the concentration of $CO_2$ from 575ppm to 731ppm(below 1,000ppm was the goal) indicating the possibility of an even management of the internal environment by installing the air circulation fan.