• Journal of the Economic Geographical Society of Korea
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• v.25 no.1
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• pp.109-130
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• 2022

The Vietnamese government has proposed contract farming through a new type of cooperative as an institutional innovation which aims to restructure the agricultural sector. However, policy changes often impact farmers, who bear the primary effects of the transition process. Understanding households' strategies for land use and livelihood is crucial for policymaking in the agricultural development field. This study was conducted in the rural Binh Dao commune in Central Vietnam. We analyzed household members' labor force changes and their livelihood behaviors after their participation in a contract farming scheme using qualitative analysis methods combined with geographic information system (GIS) support, based on secondary data and in-depth interviews of 190 farmers. Simultaneously, we created a digital map of the cooperative's production area to investigate changes in land use and production activities. The findings show that contract farming shaped the vertical coordination of the value chain from the farmers to the cooperative and agricultural product trading companies. Subsequently, it encouraged land use and labor efficiency due to mechanical support. In addition, it also increased productivity and protected farmers from market risks. However, despite its positive effects on agricultural productivity in this case, the contract farming scheme could not achieve the restructuring of the rural labor force toward non-agricultural sectors. Ironically, farmers in the Binh Dao commune tended to increase cultivable land during the agricultural restructuring program, rather than switching their labor forces to non-agricultural sectors. The lack of stable non-farming job opportunities in rural Vietnam results in challenges to the efficiency of agricultural restructuring programs. Consequently, farmers in the Binh Dao commune are still smallholder farmers, depending on the family labor force.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.5
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• pp.363-370
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• 2013

Small scale hydropower is one of most attractive and cost-effective energy technologies for installation within sewage treatment plants. This study was conducted to evaluate the potential of a semi-kaplan micro-hydropower (MHP) system for application to sewage treatment plants with high flow fluctuations and a low head. The semi-kaplan MHP is equipped with an adjustable runner blade, and is without a guide vane, so as to reduce the incidence of mechanical problems. A MHP rating 13.4 kWp with a semi-kaplan turbine has been considered for Kiheung Respia sewage treatment plant, and this installation is estimated to generate 86.8 MWh of electricity annually, which is enough to supply electricity to over 25 households, and equivalent to an annual reduction of 49 ton $CO_2$. The semi-kaplan turbine showed a 90.2% energy conversion efficiency at the design flow rate of 0.35 $m^3/s$ and net head of 4.7 m, and was adaptable to a wide range of flow fluctuations. Through the MHP operation, approximately 2.1% of total electricity demand of Kiheung Respia sewage treatment plant will be achievable. Based on financial analysis, an exploiting MHP is considered economically acceptable with an internal rate of return of 6.1%, net present value of 15,539,000 Korean Won, benefit-cost ratio of 1.08, and payback year of 15.5, respectively, if initial investment cost is 200,000,000 Korean Won.

• Journal of Korean Society of Forest Science
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• v.78 no.2
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• pp.151-159
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• 1989

The present study has been designed to define the effects of photosynthetically active radiation, leaf temperature, and water stress on photosynthesis and respiration of leaves of four oak species (Quercus mongolica, Quercus aliens, Quercus variabilis, and Quercus serrate). The results obtained are as follows : 1. The estimated light compensation points at which Pn approached zero were 38, 24, 20, and $18{\mu}Em^{-2}s^{-1}$ for Q. aliens, Q. variabilis, Q, mongolica, and Q. serrate, respectively. The light saturation points occurred at $500{\mu}Em^{-2}s^{-1}$ in three oak species except Q, aliens. 2. The maximum rates of Pn were 19.7, 15.2, 11.2, and 11.0 mg $CO_2$ $dm^{-2}h^{-1}$ for Q. variabilis, Q. serrate, Q. monglica, and Q. aliens leaves, respectively. 3. The transpiration rates of Q. variabilis and Q. serrate leaves were slightly higher than those of Q. mongolica and Q. aliens leaves at various photosynthetically active radiations(PAR), but cuticular transpiration rates at dark were similar in four oak species. 4. The optimum photosynthesis occurred at $25^{\circ}C$ in Q. aliens, Q. variabilis, and Q. serrate leaves, but $20^{\circ}C$ in Q. mongolica leaves. In four oak species, the net photosynthesis approached zero at about $40^{\circ}C$. 5. The dark respiration rates of leaves exhibited the following ranking of species : Q, variabilis > Q. mongolica > Q. aliens > Q. serrate. 6. The maximum productive efficiency (Pg/Rd) of leaves occurred highest in Q, serrate at $20^{\circ}C$, then in Q. mongolica at $20^{\circ}C$, then in Q, aliens at $25^{\circ}C$, and finally in Q. variabilis at $15^{\circ}C$. 7. The decrease of net photosynthesis in Q. serrate began at about -1.2 MPa, and then approached zero at -2.9 MPa of leaf water potential. The decrease of net photosynthesis began at 3% of water loss, and then approached zero at 17.5% of water loss. 8. As indicated by tissue-water relations parameters, it may be suggested that Q. aliens and Q. variabilis are more tolerant and favored on xeric forest soils than Q. mongolica and Q. serrate.

• Journal of the Korean Applied Science and Technology
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• v.29 no.3
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• pp.450-458
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• 2012

In order to reduce the effects of greenhouse gas (GHG) emissions, the South Korean government has announced a special platform of technologies as part of an effort to minimize global climate change. To further this effort, the Korean government has pledged to increase low-carbon and carbon neutral resources for biofuel derived from biomass to replace fossil and to decrease levels of carbon dioxide. In general, second generation biofuel produced form woody biomass is expected to be an effective avenue for reducing fossil fuel consumption and greenhouse gas (GHG) emissions in road transport. It is important that under the new Korean initiative, pilot scale studies evolve practices to produce biomass-to-liquid (BTL) fuel. This study reports the quality characteristics of F-T(Fischer-Tropsch) diesel for production of BTL fuel. Synthetic F-Tdiesel fuel can be used in automotive diesel engines, pure or blended with automotive diesel, due to its similar physical properties to diesel. F-T diesel fuel was synthesized by Fischer-Tropsch (F-T) process with syngas($H_2$/CO), Fe basedcatalyst in low temperature condition($240^{\circ}C$). Synthetic F-T diesel with diesel compositions after distillation process is consisted of $C_{12}{\sim}C_{23+}$ mixture as a kerosine, diesel compositions of n-paraffin and iso-paraffin compounds. Synthetic F-T diesel investigated a very high cetane number, low aromatic composition and sulfur free level compared to automotive diesel. Synthetic F-T diesel also show The wear scar of synthetic F-T diesel show poor lubricity due to low content of sulfur and aromatic compounds compared to automotive diesel.

• Korean Journal of Plant Resources
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• v.29 no.4
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• pp.393-399
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• 2016

This study was conducted to elucidate the photosynthetic response to the environment and establish optimum cultivation conditions for the Korean endemic plant, Aster koraiensis. Photosynthetic characteristics according to growth stage, light, CO₂, and soil water potential were investigated. During the first year of transplanting, photosynthetic rates were drastically increased until June, after which they slowly declined, During the second year, photosynthetic rates declined throughout the entire growth period. The highest level of light compensation point was shown the early growth stage. Photosynthetic rates affected by intercellular CO₂ concentration were maintained or decreased over the CO₂ saturation point. The lowest CO₂ compensation point was 16.1 μmol·mol⁻¹ during March. The morphological changes of leaves were observed due to shading with chlorophyll contents increasing. Photosynthetic rates were higher at 0% and 50% shading treatments than at 75%. There were rarely any morphological changes of leaves due to soil moisture, however, changes to leaf compactness were observed. Photosynthetic rate, apparent quantum yield, and respiration rate increased, whereas water use efficiency decreased over −25 kPa of soil moisture.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.3
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• pp.232-241
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• 1984

For the purpose of investigating the effect of chemical composition of nitrogenous fertilizers such as urea, ammonium sulfate, ammonium phosphate(dibasic) and aqua-ammonia on growth, yield, efficiency and chemical properties of paddy soil this study was carried out at the same nitrogen concentration through field experiment. The results obtained was summarized as follows. 1. Nitrogenous fertilizers had an effect on plant height at heading stage, plant weight at harvest and No. of spikelet per panicle of rice plants in decreasing order: Ammonium sulfate > Diammonium phosphate > Urea > Ammonia water. But they didn't effect on culm length, spike length, dry matter weight, No. of grain per spike, ripening ratio and weight of 1000 grains of rice plants. 2. The absorbed amount of nitrogen and that of sulfur and nitrogen availability were highest in ammonium sulfate application and lowest in ammonia water application and these were positively correlated with yield. 3. The influence of nitrogenous fertilizers on nitrogen and sulfur efficiency and translocation efficiency was insignificant but that of ammonium sulfate on nitrogen efficiency was higher than that of the others. 4. The effect of nitrogenous fertilizers on a basic chemical properties of paddy soil experimented such as pH, C.E.C, exchangeable cation and organic matter was insignificant. But the sulfur content of ammonium sulfate application and phosphorous content of diammonium phosphate application were higher than that of the others.

• Journal of Nutrition and Health
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• v.9 no.1
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• pp.92-98
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• 1976

The present studies were carried out to observe the nutritional effects of three kinds of locally produced dried infantile formula milk (DFM) and one fermented milk (FM). A feeding trial with 60 male growing albino rats weighing $60{\sim}70$ grams was conducted during 6 weeks to compare the nutritive values and protein qualities of three DFM and a FM. The diet treatments consisted of 100% control diet, 70% control diet plus 30% DFM-A, 70% control diet plus 30% DFM-B, 70% control diet plus 30% DFM-C, 100% control diet with FM and 70% control diet plus 30% DFM-B with FM. The items investigated were body weight gain, feed intake, feed efficiency ratio (FER), various organ weights, protein efficiency ratio (PER), digestibility of nutrients, biological value, utilizability of protein and intestinal microbial changes of albino rats. The results obtained are summarized as follows; 1. Although there was no statistical significance, rats fed diets containing DFMs and FM gained faster than the rats fed control diet. The best growth rate was obtained with the DFM-A and DFM-C groups. In spite of the lower protein contents of the three DFM diets than the control diet, the growth rate of albino rats fed the DFM diets was somewhat improved than rats fed control diet. 2. No statistical significance was found in feed consumption but the trend was that the feed intake of control group was higher than those of the DFM diet group. 3. Feed efficiency was inproved significantly (p<0.01) by feeding DFMs as compared with control diet. DFM-A group showed the best FER, although no statistical significance was found. 4. Rats fed the DFM diets showed significantly (p<0.01) higher PER as compared with those of the control group. But no difference was found anions DFM groups. The significant improvement (p<0.01) of PER due also to the feeding of FM was seemed to be brought about by the beneficial effect of FM. 5. The present data revealed that feeding DFM and FM didn't affect the weights of various organs of rats. 6. The protein digestibility of experimental diets was similar to each other. Although no statistical significance was found among treatments, the DFMs and FM surely tended to improve the biological value and utilizability of protein. 7. Microbial study indicated that among intestinal flora FM fed group, there were more Lactic acid bacteria than E. coli. From the experimental results described above, it may be concluded that the nutritive effects of three kinds of locally produced DFMs are much alike and the growth rate of growing albino rats can be improved by feeding either DFM or FM due to their beneficial effects on the feed efficiency and protein utilization.

• Journal of Animal Science and Technology
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• v.45 no.5
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• pp.767-776
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• 2003

An experiment was conducted to investigate the effects of dietary herbal product(Miracle$^{\circledR}$) supplementation on the performance, nutrient digestibility, fecal microflora and blood parameters in pigs. Forty eight cross bred(Y${\times}$L${\times}$D) weanling pigs (average initial body weight 7.84kg${\pm}$0.17, 28 d old) were used in 35 d feeding trial. Pigs were allotted to 16 raised floor cages(W 35.5cm${\times}$L45cm${\times}$H 55cm). Each treatment had four replications of 3 pigs each. Treatments were: control (T1), CTC 100ppm (T2), Miracle$^{\circledR}$ 0.15% (T3) and CTC 100ppm + Miracle$^{\circledR}$ 0.15% (T4). The herbal product supplementation(T3) tended to improve the weight gain, feed intake, feed/gain but there were no significant differences among treatments. Nutrient digestibility was significantly(P〈0.05) affected by dietary treatments. The pigs fed T3 diet showed the lowest digestibility of DM, crude protein, NFE, P, and amino acids among treatments. Serum cholesterol level of pigs fed T3 diet was lowest and significantly(P〈0.05) lower than those fed antibiotic supplemented diet(T2). Triglyceride and HDL level of the pigs fed T3 diet were also lower than those of others but the differences were not significant. The level of serum IgG was significantly(P〈0.05) different among treatments. The level of serum IgG was highest in T4, followed by T1, T2 and T3. Serum AST(Aspartate aminotransferase) level of the control(T1) was lower than other treatments. Levels of serum total protein, albumin and ALT(Alanine aminotransferase) were not significantly different among treatments. The colony forming units (CFU) of Lactobacillus, Cl. perfringens and E.coli in feces were not significantly different among treatments but those of Cl. perfringens of T2 (CTC 100ppm) showed the lowest count at both 3rd and 5th wk. It is concluded that herbal product Miracle$^{\circledR}$ does not significantly affect growth performance of weanling pigs but it influenced the digestibility, serum IgG, cholesterol and AST level. The combination of the herbal product Miracle$^{\circledR}$ with antibiotic(CTC) showed no synergistic effects.

• Proceedings of the KSAR Conference
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• 2001.03a
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• pp.32-32
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• 2001

본 연구는 돼지 난포란의 체외성숙시 Adenylate cyclase(ACi) 첨가가 돼지 수정란의 배발달에 미치는 효과를 검토하기 위하여 수행하였다. 돼지 난포란은 0.1% PVA, 3.05 mM D-Glucose, 0.91 mM sodium pyruvate, 0.57 mM cysteine, 0.5 $\mu\textrm{g}$/$m\ell$ LH, 0.5 $\mu\textrm{g}$/$m\ell$ FSH 그리고 10 ng/$m\ell$ EGF가 첨가된 TCM-199 배양액에서 ACi를 농도별로 첨가하여 42~44 시간 배양함으로써 체외성숙을 유도하였다. 그리고 ACi가 배발달율에 미치는 효과를 알아보기 위하여 체외수정 medium에 0, 0.1, 1% 첨가한 다음, 체외수정을 유도하고 체외배양을 실시하였다 체외성숙시 22시간 동안 ACi를 0, 0.1, 1, 및 10 $\mu\textrm{g}$/$m\ell$로 처리한 결과 33.3, 31.5, 34.1, 및 36.0%로 대조구와 처리구간의 통계학적인 유의한 차이는 나타나지 않았다. 그러나 체외성숙시 ACi을 0, 0.01, 0.1, 1.0 $\mu\textrm{g}$/$m\ell$로 처리한 결과, 25.5%, 33.3, 26.7, 및 25.6%의 배발달율이 확인되어 유의한 ACi의 처리효과가 확인되었다. 이러한 처리효과는 ACi를 0.01%로 첨한 처리구(배발달율, 33.3%)에서 가장 높게 나타났다. 그리고 체외수정시 caffeine과 ACi를 첨가한 실험에서, 1 mM caffeine과 ACi를 0, 1, 10, 20 $\mu\textrm{g}$/$m\ell$로 첨가한 결과, 대조구(30.4%)에 비해 처리구(40.9, 37.9, 및 43.5%)에서 높은 배발달율을 나타냈다. 0.5 mM caffeine과 ACi를 0, 1, 10, 20 $\mu\textrm{g}$/$m\ell$ 로 첨가시는 대조구(37.8%)와 처리구(36.5, 36.0, 및 36.0%)간의 유의한 차이는 나타나지 않았다. 또한 ACi가 배발달율에 미치는 효과를 알아보기 위하여 체외수정 배양액에 0, 0.1, 1% 첨가한 결과는 Table 1에서 보는 바와 같이, 처리구(30.3와 37.0%)가 대조구(22.6%)보다 통계학적으로 유의하게 높은 배발달율을 나타냈다. 따라서 본 연구의 결과는 체외성숙 또는 체외수정용 배양액 내에 ACi을 첨가함으로써 초기배의 발달을 효과적으로 유도할 수 있을 것이며, 앞으로 이러한 기술을 활용한다면 좀더 효율적으로 형질전환 동물이나 복제동물을 생산하게 될 것으로 사료된다.

• Journal of Korean Society of Forest Science
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• v.104 no.2
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• pp.221-229
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• 2015

The purpose of study was to broaden our knowledge on the productivity and cost of thinning operations which has become increasingly practiced in Korea. The thinning operations were conducted in a 40-year old larch (Larix leptolepis) stand, including chainsaw felling and processing at the stump, followed by yarding tree-length logs using a Koller K301-4 tower yarder. The logs were further processed and sorted into 1.8 m and 3.6 m log piles at the landing. We used a standard time study method to evaluate key variables that affect the productivity of thinning operations. The total stump-to-pile operational cost was $41,707won/m^3$. The highest cost activity was the yarding phase which cost $20,083won/m^3$ (48.2% of the total cost), followed by the costs of processing treelength materials into marketable log lengths ($12,143won/m^3$; 29.1%), and then by the costs of sorting/piling the processed logs ($5,039won/m^3$; 12.1%). It was interesting to see that felling and processing trees at the stump had low costs at $1,315won/m^3$ (3.2%) and $3,127won/m^3$ (7.5%), respectively. We used the detailed time study data to develop regression equations which were to predict yarding productivity. Our analysis showed that harvesting system cost was highly sensitive to the number of logs, yarding distance and lateral distance per turn, respectively.