• Membrane and Water Treatment
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• 제12권1호
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• pp.43-49
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• 2021

The Commercial polymeric membranes like Polysulfone (PSF), Polyvinylidene difluoride (PVDF) and Polyacrylonitrile (PAN) which are an integral part of water purification investigation were chosen for the shockwave (SW) exposure experiment. These membranes were prepared by blending polymer (wt. %) / DMF (solvent) followed by phase-inversion casting technique. Shockwaves are generated by using Reddy Tube lab module (Table-top Shocktube) with range of pressure (1.5, 2.5 and 5 bar). Understanding the changes in membrane before and after shock wave treatment by parameters, i.e., pure water flux (PWF), rejection (%), porosity, surface roughness (AFM), morphology (SEM) and contact angle which can significantly affect the membrane's performance. Flux values PSf membranes shows increase, 465 (pristine) to 524 (1.5wt%) LMH at 50 Psi pressure and similar enhancement was observed at 100Psi (625 to 696 LMH). Porosity also shows improvement from 73.6% to 76.84% for 15wt% PSf membranes. It was observed that membranes made of polymers such as PAN and PSF (of high w/w %) exhibits some resistance against shockwaves impact and are stable compared to other membranes. Shockwave pressure of up to 1.5 bar was sufficient enough to change properties which are crucial for performance. Membranes exposed to a maximum pressure of 5 bar completely scratched the surface and with minimum pressure of 1.5bar is optimum enough to improve the water flux and other parameters. Initial results proved that SW may be suitable alternative route to minimize/control membrane fouling and improve efficiency.

• 농업과학연구
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• 제48권1호
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• pp.133-140
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• 2021

The aim of this study was to evaluate the growth performance between two different crossbred strains of Korean native chickens denoted as 1A and 2A compared to white semi broilers and Ross (RR) from hatching to 40 days. In total, 576 one-day-old chicks were allocated in a completely randomized design to give 18 replicate cages each (eight chicks per cage). The two-phase feeding program consisted of the starter (day 1 - 21: Crude protein [CP] 20% and metabolizable energy [ME], 3,050 kcal·kg^-1) and the grower (day 22 - 40: CP 18%, 3,100 kcal·kg^-1). The results revealed that 1A and 2A had a lower (p < 0.05) body weight (BW) from day 1 to day 40 compared with the other groups. A lower (p < 0.05) average daily gain (ADG) was observed in 1A and 2A during the entire period when compared with the other groups. The 1A and 2A groups had the minimum (p < 0.05) average daily feed intake (ADFI) compared with the other groups for the whole period. The RR had an improved (p < 0.05) FCR compared with the other groups during the whole period. The 1A and 2A groups were observed to have the lowest (p < 0.05) shank length compared with the other groups during the entire period.

• 한국정보통신학회논문지
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• 제26권5호
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• pp.649-655
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• 2022

본 논문에서는 음성존재확률을 활용한 2채널 입력신호 상관행렬의 행렬식 기반 잡음제거 기법을 제안하였다. 제안한 기법은 음성존재확률을 이용해 기존의 행렬식 기반 2채널 잡음제거 기법의 위너 필터 이득을 음성과 잡음구간에 따라 적응적으로 조절함으로써 잡음제거 성능을 더욱 향상시키고자 하였다. 제안한 기법은 잡음 종류, 반향 조건, 신호대잡음비, 잡음원의 개수와 방향이 다양한 모의 환경에서 객관적 평가 방법을 통해 평가되었다. 실험 결과는 대부분의 실험환경에서 행렬식 기반의 기법들이 위상차를 기반으로 한 기법들보다 성능이 우수했고 특히 제안한 음성존재확률을 이용한 행렬식 기반 잡음제거기법이 음성 신호 왜곡을 최소화하면서 가장 우수한 잡음 제거 성능을 보였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권2호
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• pp.520-541
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• 2023

In CRNs, SS is of utmost significance. Every CR user generates a sensing report during the training phase beneath various circumstances, and depending on a collective process, either communicates or remains silent. In the training stage, the fusion centre combines the local judgments made by CR users by a majority vote, and then returns a final conclusion to every CR user. Enough data regarding the environment, including the activity of PU and every CR's response to that activity, is acquired and sensing classes are created during the training stage. Every CR user compares their most recent sensing report to the previous sensing classes during the classification stage, and distance vectors are generated. The posterior probability of every sensing class is derived on the basis of quantitative data, and the sensing report is then classified as either signifying the presence or absence of PU. The ISVM technique is utilized to compute the quantitative variables necessary to compute the posterior probability. Here, the iterations of SVM are tuned by novel GO-PSA by combining GOA and PSO. Novel GO-PSA is developed since it overcomes the problem of computational complexity, returns minimum error, and also saves time when compared with various state-of-the-art algorithms. The dependability of every CR user is taken into consideration as these local choices are then integrated at the fusion centre utilizing an innovative decision combination technique. Depending on the collective choice, the CR users will then communicate or remain silent.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권8호
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• pp.2188-2208
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• 2023

Quality of Service (QoS) is a critical feature of Wireless Sensor Networks (WSNs) with routing algorithms. Data packets are moved between cluster heads with QoS using a number of energy-efficient routing techniques. However, sustaining high scalability while increasing the life of a WSN's networks scenario remains a challenging task. Thus, this research aims to develop an energy-balancing component that ensures equal energy consumption for all network sensors while offering flexible routing without congestion, even at peak hours. This research work proposes a Gravitational Blackhole Search Optimised splay tree routing framework. Based on the splay tree topology, the routing procedure is carried out by the suggested method using three distinct steps. Initially, the proposed GBSO decides the optimal route at initiation phases by choosing the root node with optimum energy in the splay tree. In the selection stage, the steps for energy update and trust update are completed by evaluating a novel reliance function utilising the Parent Reliance (PR) and Grand Parent Reliance (GPR). Finally, in the routing phase, using the fitness measure and the minimal distance, the GBSO algorithm determines the best route for data broadcast. The model results demonstrated the efficacy of the suggested technique with 99.52% packet delivery ratio, a minimum delay of 0.19 s, and a network lifetime of 1750 rounds with 200 nodes. Also, the comparative analysis ensured that the suggested algorithm surpasses the effectiveness of the existing algorithm in all aspects and guaranteed end-to-end delivery of packets.

• 해양환경안전학회지
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• 제29권3호
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• pp.255-269
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• 2023

Surface water temperature of a bay (from the south to the north) increases in spring and summer, but decreases in autumn and winter. Due to shallow water depth, freshwater outflow, and weak current, the water temperature in the central to northern part of the bay is greatly affected by the land coast and air temperature, with large fluctuations. Water temperature variations are large in the north-east coast of the bay, but small in the south-west coast. The difference between water temperature and air temperature is greater in winter and in the south-central part of the bay than that in the north to the eastern coast of the bay where sea dykes are located. As the bay goes from south to north, the range of water temperature fluctuation and the phase show increases. When fresh water is released from the sea dike, the surrounding water temperature decreases and then rises, or rises and then falls. The first mode of empirical orthogonal function (EOF) represents seasonal variation of water temperature. The second mode represents the variability of water temperature gradient in east-west and north-south directions of the bay. In the first mode, the maximum and the minimum are shown in autumn and summer, respectively, consistent with seasonal distribution of surface water temperature variance. In the second mode, phases of the coast of Seosan~Boryeong and the east coast of Anmyeon Island are opposite to each other, bordering the center of the deep bay. Periodic fluctuation of the first mode time coefficient dominates in the one-day and half-day cycle. Its daily fluctuation pattern is similar to air temperature variation. Sea conditions and topographical characteristics excluding air temperature are factors contributing to the variation of the second mode time coefficient.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2009년도 한국우주과학회보 제18권2호
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• pp.38.1-38.1
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• 2009

In this paper we present the first results of summer-time F region irregularities during low solar condition observed using the Gadanki MST radar. Echoes were observed on all 20 nights of radar observations and were mostly confined to the post-midnight hours. Echo morphology is very different from the equinoxial post-sunset plume-like features reported earlier from Gadanki. Echo SNRs are lower by 25 dB than their equinoxial post-sunset counterpart, and are quite comparable to the equinoxial irregularities in the post-midnight hours, which are essentially the decaying post-sunset irregularities. The Doppler velocities, which lie in the range of $\pm$ 100 m s-1, show upward/northward motion of the irregularities during the initial phase in contrast to the observed predominant downward/southward velocities associated with the decaying equinoxial post-midnight F region irregularities. Spectral widths of the summer echoes, which are well below 50 m s-1 and are very similar to those of the decaying equinoxial irregularities, represent the presence of weak plasma turbulence. Simultaneous observations made using a collocated ionosonde show no ionogram trace during 2200-0530 LT except for a few occasions. Weak frequency type spread F observed during midnight hours occurred without prior occurrence of range spread F. Concurrent ionosonde observations made from magnetic equatorial location Trivandrum also show very similar result and thus no height rise of the F layer during the midnight hours could be monitored. The preliminary analysis suggests that the post-midnight irregularities reported here are mostly freshly generated ones. The observations are discussed in the light of other observational results reported earlier and the current under standing on the post-midnight occurrence F region irregularities in summer.

• 무역학회지
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• 제46권2호
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• pp.19-38
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• 2021

This study aims to analyze the foreign asset leverage effect on Korean oil & gas companies' foreign profits and to maintain the appropriate foreign asset volume for reducing exchange risk. For a long time, large Korean companies, including oil companies, overheld foreign currency liabilities. For this reason, most large companies have been burdened to hedge exchange risk and this excess limit holding deteriorated total profit and reduced foreign currency asset management efficiency. Our paper proceeds in presenting a three-stage analysis considering diversified exchange risk factors through estimation on transformation of foreign transactions a/c including annual trends of foreign asset and industry specifics. We also supplement incomplete the estimation method through a practical hedging case investigation. Our research parts are differentiated on the analyzing four periods considering period-specifics The FER value of the oil firms ranged from -0.3 to +2.3 over the entire period. The results of the FER Value are volatile and irregular; those results do not represent the industry standard comparative index. The Korean oil firms are over the credit limit without accurate prediction and finance high interest rate funds from foreign-owned banks on the basis on a biased relationship. Since the IMF crisis, liabilities of global firms have decreased. Above all, oil firms need to finance a minimum limit without opportunity losses on the demand forecast and prepare for uncertainty in the market. To reduce exchange risk from the over-the-limit position, we must consider factors that affect the corporate exchange risk on the entire business process, including the contract phase.

• Design & Manufacturing
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• 제17권3호
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• pp.15-20
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• 2023

In the fine blanking process, which is a press operation known for producing parts with narrow clearances and high precision through the application of high pressure, die roll often occurs during the shearing process when the punch penetrates the material. This die roll phenomenon can significantly reduce the functional surface of the parts, leading to decreased product performance, strength, and fatigue life. In this research, we conducted an in-depth analysis of the factors influencing die roll in the curvature area of the fine blanking process and identified its root causes. Subsequently, we designed and experimentally verified a die roll reduction process specifically tailored for the door latch manufacturing process. Our findings indicate that die roll tends to increase as the curvature radius decreases, primarily due to the heightened bending moment resulting from reduced shape width-length. Additionally, die roll is triggered by the absorption of initial punch energy by scrap material during the early shearing phase, resulting in lower speed compared to the product area. To mitigate the occurrence of die roll, we strategically selected the Shaving process and carefully determined the shaving direction and clearance area length. Our experiments demonstrated a promising trend of up to 75% reduction in die roll when applying the Shaving process in the opposite direction of pre-cutting, with the minimum die roll observed at a clearance area length of 0.2 mm. Furthermore, we successfully implemented this approach in the production of door latch products, confirming a significant reduction in die roll. This research contributes valuable insights and practical solutions for addressing die roll issues in fine blanking processes.

• 한국어류학회지
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• 제3권1호
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• pp.48-57
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• 1991

1988년(年) 4월(月)부터 10월(月)까지 전라남도(全羅南道) 영암군(靈岩郡) 삼호면(三湖面) 조간대(潮間帶)에서 월별(月別)로 채집(採集)된 자성(雌性)짱뚱어 Boleophthalmus pectinirostris(Linnaeus)를 대상(對象)으로 간세포(肝細胞)의 활성변화(活性變化)를 조사(調査)하기 위해 투과전자현미경(透過電子顯微鏡)으로 관찰하였고, GSI와 HSI의 월별변화(月別變化)와 난소발달단계(卵巢發達段階)에 따른 간조직(肝組織)의 단백질(蛋白質) 및 핵산함양(核酸含量)(총(總) RNA, DNA)의 변화(變化)를 조사(調査)하였다. GSI는 성장기(成長期)인 5월(月)부터 증가하기 시작하여 성숙기(成熟期)인 6월말(月末)에 연중(年中) 최대치(最大値)를 나타내었고, 산란기(産卵期)인 7월말(月末)부터 다시 감소하기 시작하여 퇴화기(退化期)인 9월말(月末)에 최저(最低)값을 나타내었다. HSI의 월별변화는 GSI와 역상관(逆相關) 관계(關係)를 갖는다. 난소(卵巢)가 성숙(成熟)하는 하계(夏季)에는 HSI값이 떨어지고 난소(卵巢)가 퇴화(退化)되는 10월(月) 중순(中旬)에는 HSI값이 최대(最大)에 이른다. 성숙기(成熟期)인 6월(月)에 암컷의 간조직(肝組織)의 간세포(肝細胞)들은 증대(增大)되고 핵(核)들은 비대(肥大)되었으며, 간세포내(肝細胞內)에는 글리코겐 입자(粒子)들과 지방적(脂肪滴)들이 정차로 감소되는 반면, 수많은 조면소포체(粗面小胞體)들은 증가(增加)되었다. 그리고 리보소옴이 부착된 잘 발달한 조면소포체(粗面小胞體)들은 세포질내(細胞質內)에서 단백질(蛋白質) 합성(合成) 및 vitellogenin 축적(蓄積)에 중요한 역할을 하는 것으로 추정된다. 산란기(産卵期)인 7월(月)에 글리코겐 입자(粒子)들과 지방적(脂肪滴)들은 점차로 증가되었으며, 이들 물질(物質)은 퇴화기(退化期)인 8월말에도 다량(多量)이 그대로 관찰되었다. 난소(卵巢)의 발달시기(發達時期)에 따른 암컷 간조직(肝組織) 1gr 당(當) 단백질함양(蛋白質含量)은 성숙기(成熟期)인 6월에 최고값($4.720{\pm}0.103mg/g$)을 보였으며, 그후 점차 줄어들어 산란기(産卵期)인 7월에는 최저값($3.640{\pm}0.130mg/g$)을 나타낸 후, 퇴화기(退化期)인 8월에 다시 점점 증가하는 양상을 보였다. 또한 간조직내(肝組織內)의 핵산(核酸), 즉 RNA함량(含量)은 6월에 최고값($0.523{\pm}0.040mg/g$)을 나타내었으며, 그후 점차 감소하여 7월에는 최저값($0.158{\pm}0.006mg/g$)을 나타내었고, 다시 8월에는 약간 상승하였다. 이 결과로 볼 때 단백질(蛋白質) 함량(含量)과 RNA함량(含量)과의 관계(關係)는 밀접(密接)한 관계(關係)를 나타내었다. 간조직(肝組織) 중량(重量)(g) 당(當) 총(總) DNA 함량(含量)은 시기별(時期別)로 약간의 수치상(數値上) 차이(差異)는 있지만 거의 비슷하였다. 총(總) RNA/DNA의 비율(比率)은 6월(月)에 0.745, 7월(月) 0.262, 8월(月) 0.341이었다.