• Journal of the Korean Institute of Gas
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• v.5 no.3 s.15
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• pp.15-22
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• 2001

Reliability evaluation of welded structures by mechanical testing of weld heat-affected zones (HAZs) has become general practice throughout the world. HAZs of steel welded Joints show a gradient of microstructure from the fusion line to the unaffected base metal. This study is concerned a correlation between the microstructural change and the fracture characteristics in HAZs of both seam and girth welds of API 5L X65 pipeline steel, which is generally used for natural gas transmission pipelines in Korea. The focus in this study is the investigation of macroscopic fracture behavior of the various regions within HAZ. Changes in microstructure and toughness were observed using actual HAZ specimens. To evaluate the macroscopic toughness of actual HAZ, Charpy V-notch impact test and CTOD test were performed.

• Journal of Animal Environmental Science
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• v.10 no.1
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• pp.37-46
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• 2004

In order to investigate the effect of floor condition on the fattening performance of cattle, sixteen finishing Hanwoo steers of weighting 570kg were fed for 16 weeks to slaughter on two types of sawdust bedding pen oriented to the south(SP) and the north(NP) then obtained following results. The floor condition of SP roofed by transparent material was dry and flat during overall experimental period, whereas, that of NP roofed by solid slate was muddy and rough even in summer and fall, and then frozen in winter period resulted in interfering with the locomotion and resting behavior of steers. Average daily dry matter intake of steers was not different between tow treatments, however, the average daily gain of steers in NP and SP was 0.64kg and 0.75kg, respectively, meaning that gained 14.3% less for the NP group(p<0.05), accordingly, feed requirement(feed/gain) and TDN/gain increased by 15.9% and 15.5%, respectively. No significant differences were found in slaughter weight, carcass weight, dressing percentage, meat yield index and meat quality traits between two treatments. In conclusion, this study revealed that poor floor condition of feeding pen could decrease weight gain and feed efficiency of cattle by increasing energy consumption for locomotion and conductive energy loss while resting on the floor surface. These results indicates that housing orientation of cattle shed and the selection of roof material are important factors in beef cattle production.

• Journal of Animal Science and Technology
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• v.48 no.4
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• pp.493-502
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• 2006

The slaughter weight (wt) is a most important economic factor in swine roduction. The present study was undertaken to determine if it is feasible to increase the slaughter wt of finishing pigs to 130kg without significantly affecting the growth efficiency and carcass quality. One hundred and sixty gilts and 160 barrows born from lean-type Yorkshire×Landrace (YL)-dam and Duroc (D)-sire lines, which are most widely used for terminal breeding for pork production in Gyeongsangnam-do, were randomly allocated into 16 pens under a 2 (sex)×2 (slaughter wt; 110 vs. 130kg) factorial arrangement of treatments. The animals were fed ad libitum a diet containing 3,200kcal DE/kg and 15.5% crude protein. After slaughter at the predetermined wt, yields of trimmed primal cuts and physicochemical characteristics of the longissimus dorsi muscle (LD) were measured or analyzed. Average daily gain was greater (P<0.01) in barrows than in gilts (0.86 vs. 0.79kg), but it was not different between the 110- and 130-kg slaughter wt groups (P>0.05). Backfat thickness was greater in the 130- vs. 110-kg group in both sexes (gilts: 21.6 vs. 17.6 mm, barrows: 25.1 vs. 20.8 mm). The yield percentage of belly was greater in barrows than in gilts (21.2 vs. 20.5%) and also in the 130-kg vs. 110-kg group (21.4 vs. 20.2%). Major physicochemical characteristics of LD including the color, percentage of 48-h drip loss, 24-h pH and percentages of crude protein and fat were not influenced by slaughter wt. Marginal profit of the 130-kg vs. 110-kg market pig was approximately 󰠏20,000 won/head, which resulted primarily from the heavy carcass weight of the former exceeding the upper limit of the A- or B-grade. However, if it had not been for the carcass weight limit of the current grading system, a 130-kg market pig would have had a potential marginal profit greater than 20,000 won. Results suggest that slaughter wt of lean-line finishing pigs can be increased to 130kg without significantly compromising the growth efficiency and carcass quality and accordingly, the upper weight limit of the ‘good-grade’ carcass needs to be increased or abolished to accommodate the larger market pigs.

• Journal of the Korean Society for Marine Environment & Energy
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• v.6 no.1
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• pp.44-59
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• 2003

The three-dimensional eco-hydrodynamic model was applied to estimate the effect of water quality improvement by the effluent treatment of landbase-seawater culture system in the Kamak bay The computed residual currents were dominated southward flow at the northern narrow strait and eastward flow and clockwise water circulation at the mouth of the bay, strongly. The mean relative errors of DIP, DIN and COD between the simulated and observed results at 9 stations in the Kamak bay were shown 14.3％, 25.8％ and 14.4％, respectively. There were high concentrations of DIP, DIN and COD at the northwestern bay which is influenced by pollution loads. The simulations were performed using an ecosystem model under the conditions of DIP 90％, DIN 80％ and COD 60％ treatment efficiency by the ozone treatment system of landbase-seawater culture system. As a results of simulation, the improvement effects of DIP, DIN and COD are 34.4~54.0％ (average 46.4％), 0.4~25.4％(average 8.4％) and 15.6~29.4％(average 22.7％), respectively. Therefore the area of seawater quality grade I based on COD was extended in the bay.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.2
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• pp.83-99
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• 2005

To evaluate environmental charateristics of the South Sea and East China Sea on summer, water and sediment quality were measured in June 2001-2003. Surface layer was affceted by Warm water originated from the high temperature and salinity-Tsushima Warm Current, on the other hand, Yellow Sea Cold Water was spread to the bottom layer in the south-western part of the Jeju island, and salinity at stations near the Yangtze River was decreased below 29psu because of a enormous freshwater discharges. Thermocline-depth was formed at about 10m, and chlorophyll maximum layer was existed in and below the thermocline. COD(Chemical Oxygen Demand), TN(Total Nitrogen), and TP(Total Phosphorus) concentrations showed seawater quality grade II in surface layer of the most area, but concentrations of such as COD, Chl. a, TSS(Total Suspended Solid), and nutrients were greatly increased in the effect area of Yangtze River discharges. Correlations between dissolved inorganic nitrogen, Chl. a and salinity were negative patterns strongly, in contrast, those of inorganic phosphorus, COD and Chl. a were positive, which indicates that phytoplankton biomass and phosphorus are considered as important factors of organic matter distribution and algal growth, respectively. in the study area. The distribution of ignition loss, COD, and $H_2S$ of surface sediment were in the ranges of 2.61-8.81%, $0.64-11.86mgO_2/g-dry$, and ND-0.25 mgS/g-dry, respectively, with relatively high concentration in the eastern part of the study area. Therefore, to effective and sustainable use and management of this area, continuous monitoring and countermeasures about major input sources to the water and sediment, and prediction according to the environmental variation, are necessary.

• Resources Recycling
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• v.19 no.3
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• pp.24-32
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• 2010

In the present work, a new separation system with rotating rakes has been developed to separate the film-based plastics from the recyclable materials, and environment assessment is also carried out during operation of the device. Capacity of the device was about 5.3 ton/hr at a rakes rotation speed of 26.0 rpm (the number of rakes in the 1st, 2nd and 3rd trials were 39, 52 and 48, respectively) and a belt conveyor speed of 38.5m/min, which satisfied the initial design capacity (5.0 ton/hr). Recovery ratio and purity of the plastic films were 92.6% and 96.5%, respectively at a rotation speed of 28 rpm. The levels of noise, vibration and particulate emission were below material standard regulatory limits. Plastic refused fuel (RPF) was also prepared with the recovered films. The calorific value and chlorine content of the prepared RPF were 9,740 kcal/kg and 0.18%, respectively which satisfy the first grade quality specification of the Korean RPF standard. As a result of this work, recovery of energy resources from the municipal solid waste is possible by adopting the developed separation device.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1145-1148
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• 2007

한국을 비롯하여 논농사 중심지역에서는 하천 주변이 과거에는 농경지로, 그리고 오늘날은 도시지역으로 개발되어 하천의 원형이 거의 유지되지 못하고 있다. 하천은 수역과 수변으로부터 거리에 따라 여러 개의 이질적 생태적 공간이 이어지는 복합생태계로서 하나의 경관으로 볼 수 있다. 하천이 하나의 온전한 생태적 계로서 기능을 발휘하기 위해서는 이들을 모두 포함하는 하천의 원형이 복원되어야 한다. 현존하는 하천복원사업이 수변 구역의 복원에 초점을 맞추고 있지만, 진정한 복원이 이루어지기 위해서는 온전한 강변 식생의 복원이 선결과제이다. 본 연구에서는 유적군락의 형태로 잔존하는 강변 식생을 조사하여 식생복원 모델로 삼고자 한다. 수위와 침수체제에 의해 하천의 횡단구조를 수변, 홍수터 및 제방으로 구분한 후 각 지소의 적합한 식생단위를 구분하여 생태적 복원을 실현하기 위한 정보를 구축하였다. 수변식생으로는 달뿌리풀군락과 갈대군락이 자주 출현하고, 홍수터에는 갯버들군락과 키버들군락이 우세하였다. 그 중 전자의 식물군락은 하상재료가 거친 입자의 지소에 성립하고, 후자의 것은 미세한 입자의 지소에 성립하는 경향이었다. 제방역에는 버드나무군락, 다릅나무군락, 귀룽나무군락, 물푸레나무군락, 산사나무군락, 신나무군락(한탄강 지류), 참느릅나무군락, 물푸레나무-갈참나무군락(한탄강 본류), 오리나무군락(민통선 북방지역), 소나무군락, 황철나무군락, 느릅나무군락(소양강 상류), 왕버들군락(금강 중류) 등이 성립하였다. 이러한 식생정보를 하천의 지리적인 위치에 따라 구분하였고, 생태적 복원 시 도입식물을 결정하기 위한 자료로 삼기 위해 각 식생단위를 이루는 종 조성을 정보 체계화하였다.을 효율적으로 하기 위하여 Solar Unit으로부터 나오는 전기를 중전기에서 밧데리로 축전을 시키고 완전 충전 후에는 나머지 전기는 방전이 되도록 회로를 구성하였다. 사통수문 자원조사 결과에 의하면 현재 저수지에 물공급을 하는 수문은 취수탑 형식이 70% 이상을 차지하고 있으며 나머지 30%의 사통수문 중 원형수문비가 98% 이상을 차지하고 있다. 현재 대체에너지를 사용하는 저수지 사통수문은 없는 것으로 조사되었으며 전력을 사용하는 사통도 조사결과에 의하면 20% 이내로 나타났다. 이러한 결과는 향후 수리시설 개보수시 적은 예산으로 사업을 시행하는 경우 사통수문의 설치방향의 지표가 될 것으로 판단되며 수리시설의 운영관리에 대한 새로운 대안으로 제시할 수 있다.분류되었다. 지표 유거가 많아 배수등급이 매우양호로 분류되던 토양은 정 등(1995)의 분류와 비교하여 대부분 강우 유출 가능성이 큰 쪽으로 조정되었다. 새로운 수문학적 토양유형을 이용할 경우 낮은 토심에서 암반층이 발견되는 산림토양이 분포한 유역이나 산림, 밭 등에 식질 토양이 많이 분포하는 유역에서는 기존의 방법을 이용하는 것보다 강우 유출량이 높게 평가될 것으로 판단된다. 앞으로 강우 유출량 실측자료와의 비교를 통해 지속적인 보정을 하여야 할 것이며 특히 불투수층의 존재시 일괄적으로 D유형으로 분류된 토양의 경우 깊이에 따라 C 또는 D 유형으로 세분하여 조정할 필요가 있다.가 있었다. 에틸아세테이트분회물의 경우 디글로로메탄 분회물에 비해 다소 낮은 저해효과를 나타내었지만 250 ${\mu}$g/ml 농도에서 약 60%의 세포독성 효과를 나타내었다. 디클로로메탄 분획물과 에틸아세테이트 분

• Korean Chemical Engineering Research
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• v.56 no.5
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• pp.631-640
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• 2018

The application of an oxy-combustion circulating fluidized bed combustor (Oxy-CFBC) for low grade coals has recently developed in the world to meet the continuous increase of energy demand and to achieve the reduction of greenhouse gases. Since demo plants for Oxy-CFBC have been developed, the combustion properties of Oxy-CFBC in various operation conditions, such as gas flow rates, combustion temperature, fuel, and so on, should be investigated to develop design criteria for a commercial Oxy-CFBC. In this study, a computational simulation tool for Oxy-CFBC was developed on the basis of the IEA-CFBC (International Energy Agency Circulating Fluidized Bed Combustor) model. Simulation was performed under various conditions such as reaction temperature ($800^{\circ}C{\sim}900^{\circ}C$), oxygen contents (21%~41%), coal feeding rate, Ca/S mole ratio (1.5~4.0), and so on. Simulation results show that the combustion furnace temperature is higher in oxy 1 than air fired. However, the temperature gradient tended to decrease with increasing oxy mixing percent. In case of $SO_x$, the higher the Ca/S mole ratio and oxy mixing percent, the higher the desulfurization efficiency.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.4
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• pp.213-223
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• 2011

The status and changes of water quality of national fishing harbors and designated ports in East Coast of Korea were analyzed to support establishment effective water environmental management. COD (Chemical Oxygen Demand) concentration was satisfied to designated water quality criteria in most areas, but TN (Total Nitrogen) and TP (Total Phosphorus) exceeded the criteria frequently. Also, peak concentration was summer in COD and SS (Suspended Solid), but winter in TP. Eutrophication index of Ganggu and Pohang (old) area were the highest. Pollution index by function of COD, TN, and TP of Ganggu, Pohang, Jumunjin, and Guryongpo was high with gradual increasing recently, on the contrary, that of Samcheok, Imwon, and Chuksan was decreased. Pollution index involving multi-indictors relation to organics and inorganics was necessary for water quality assessment. Designated water quality criteria needed to be improved because the criteria of Jukbyun and Chuksan was applied more strictly compared to the other regions although without difference of environmental characteristics. Furthermore, the criteria notified lately needed to be related to management pollutants from land-based sources. The continuous diagnosis and monitoring on sediment quality within the study area were necessary for prevention of water pollution and eco-friendly disposal of dredged sediment. Especially, monitoring of Designated Ports was implemented partially, however monitoring ratio of National Fishing Har-bors was 7% to whole part. Therefore, systematic and integrated environmental monitoring for ports and harbors with charge of national management was reestablished by strengthening and securing a legal basis.