• Current Optics and Photonics
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• 제7권5호
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• pp.574-581
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• 2023

A scheme is proposed to generate triangular waveforms with alterable symmetry. The key component is a cascaded single-drive Mach-Zehnder modulator (SD-MZM) and optical polarization beam splitter-combiner architecture. In this triangular waveform generator, the bias-induced phase shift, modulation index and controllable delay difference are changeable. To generate triangular waveform signals with different symmetry indexes, different combinations of these variables are selected. Compared with the previous schemes, this generator just contains one SD-MZM and the balanced photodetector (BPD) is not needed, which means the costs and energy consumption are significantly reduced. The operation principle of this triangular waveform generator has been theoretically analyzed, and the corresponding simulation is conducted. Based on the theoretical and simulated results, some experiments are demonstrated to prove the validity of the scheme. The triangular waveform signals with a symmetry factor range of 20-80% are generated. Both experiment and theory prove the feasibility of this method.

• 에너지공학
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• 제19권4호
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• pp.246-250
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• 2010

12 리터급 경유엔진을 개조한 LNG 혼소엔진에 대해 출력, 연비 및 배출가스등의 성능을 평가하였으며 이를 바탕으로 LNG혼소 화물 자동차의 경제성을 분석하였다. 출력은 경유엔진에 비해 5% 정도 낮은 수준으로 평가되었으며 엔진효율은 경유의 경우 37.4%, LNG혼소의 경우 35.9%로 경유엔진의 경우가 다소 높게 나타났다. 배출가스는 탄화수소를 제외하고 PM, NOx, CO 및 $CO_2$는 LNG 혼소의 경우가 낮은 특성을 보였다. 경제성 비교를 위해 연료비용과 환경비용 관점에서 각각 분석하였으며 유가보조금 및 할인을고려할 경우에도 LNG 혼소 화물차의 경제성이 있는 것으로 분석되었다.

• 한국환경과학회지
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• 제23권2호
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• pp.165-170
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• 2014

Despite abundant nutritions, krill is barely used for human consumption. The objective of this study was to investigate the nutritional component and amino acid composition of krill and further utilizes it for food resource. Proximate compositions of krill meal were consisted of crude protein 58.85%, ash 13.89%, crude fat 12.45%, carbohydrate 11.01% and moisture 3.80%. The amount of total amino acid was 54.74 g%, and the major amino acids were glutamic acid (7.71 g%), aspartic acid (6.20 g%), leucine (4.72 g%), lysine (4.41 g%), arginine (6.49 g%) and alanine (3.25 g%), respectively. Total essential amino acid content was 21.87%, and the major amino acids were leucine (4.72 g%), lysine (4.41 g%) and isoleucine (2.90 g%), respectively. Content of total free amino acid in krill meal was 20224.30 mg/kg, and the major free amino acids were taurine (4501 mg/kg), arginine (3130.60 mg/kg), proline (2302.90 mg/kg), alanine (2088.10 mg/kg), glycine (1606.40 mg/kg) and lysine (1197.40 mg/kg). Especially, taurine was the most abundant of all free amino acids. Thus, these data indicate that krill seems to be abundant protein source food.

• 대한임베디드공학회논문지
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• 제11권2호
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• pp.67-78
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• 2016

The emerging Spin-Transfer Torque RAM (STT-RAM) is a promising component that can be used to improve the efficiency as a result of its high storage density and low leakage power. However, the state-of-the-art STT-RAM is not ready to replace SRAM technology due to the negative effect of its write operations. The write operations require longer latency and more power than the same operations in SRAM. Therefore, a hybrid cache with SRAM and STT-RAM technologies is proposed to obtain the benefits of STT-RAM while minimizing its negative effects by using SRAM. To efficiently use of the hybrid cache, it is important to place write intensive data onto the cache. Such data should be placed on SRAM to minimize the negative effect. Thus, we propose a technique that optimizes placement of data in main memory. It drives the proper combination of advantages and disadvantages for SRAM and STT-RAM in the hybrid cache. As a result of the proposed technique, write intensive data are loaded to SRAM and read intensive data are loaded to STT-RAM. In addition, our technique also optimizes temporal locality to minimize conflict misses. Therefore, it improves performance and energy consumption of the hybrid cache architecture in a certain range.

• 반도체디스플레이기술학회지
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• 제22권4호
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• pp.13-18
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• 2023

A subway station is a prominent multi-purpose facility where the quantitative management of fine dust, generated by various factors, is conducted. Recently, eco-friendly air purification methods using air-purifying plants are being discussed, with the focus on biofiltration through vegetation. Previous research in this field has confirmed the reduction effects of transition metals such as Fe, which have been identified as harmful to human health. This study aimed to identify the sources of fine dust dispersion within subway stations and derive an efficient operational strategy for air-purifying plants that takes into account the behavior characteristics of fine dust within multi-purpose facilities. The experiment monitored regional fine dust levels through IAQ stations established based on prior research. Also, the data was analyzed through time-series and correlation analyses by linking it with passenger counts at subway stations and the frequency of train stops. Furthermore, to consider energy efficiency, we conducted component-specific power consumption monitoring. Through this study, we were able to derive the optimal operational strategy for air-purifying plants based on time-series comprehensive analysis data and confirm significant energy efficiency.

• 한국광물학회:학술대회논문집
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• 한국광물학회.대한자원환경지질학회.대한광업진흥공사 2002년도 추계 공동 심포지엄 논문집: 국내 자원의 현황과 전망
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• pp.53-67
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• 2002

As in the past, we are concerned today with the magnitudes of mineral resources and the adequacy of these resources to meet future needs. In looking at global resource issues, we should consider the need for the resource, its supply, and the environmental consequences of using it. The need for a resource can become a resource dependency, especially as the global population expands and each of us becomes increasingly dependent upon hundreds of natural materials. Therefore, our great mineral consumption makes the human population a true 'Geologic Force', which will be even more significant in the future when the global population is projected to reach alarming proportions. Although our supplies of mineral resources probably will be sufficient for the 21s1 century, the uneven distribution of minerals in the Earth's crust almost certainly will continue to be a major problem The most likely result will be major shifts in both prices and sources of supply of many mineral resources. As for energy resources, we must avoid an obsessive dependency on one fuel and expand instead to thor energy resources. Finally, because the use of resources affects the environment, we need to focus on resource exploitation and global pollution, particularly in regard to ground water and arable land. We must manage our resources so as to be in balance with our environment. And the accelerated industrialization of South Korean economy over the last three decades has resulted in the mass consumption of nuneral commodities. South Korea has around 50 useful mineral commodities for the mineral industry, among 330 kinds of minerals described. The component ratio of the mining industry sector of the gross national production(GNP) in South Korea dropped from $1.2\%\;in\;1971\;to\;0.34\%$ in 1997 due to the rapid growth of other industries In the countxy. During the period from 1971 to 1997, the average growth rate of mineral consumption in South Korea was $9.13\%$ yearly and that of GNP per capita was $14.97\%$. The mineral consumptions per capita showed a continual Increase during the last 30 years as follows(parenthesis. GNP per capita): 0.99 metric tons in 1971($\$289$), 3.83 metric tons in 1989($\$5,210$), 6.11 metric tons in 1995 ($\$10,037$), and 6.66 metric tons in 1997($9,511). The total amount of mineral consumption in South Korea was 33 million tons of 32 mineral commodities in 1971, and 306 million metric tons of 47 mineral commodities In 1997.

• 대한자원환경지질학회:학술대회논문집
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• 대한자원환경지질학회 2002년도 추계 공동 심포지엄 논문집
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• pp.53-67
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• 2002

As in the past, we are concerned today with the magnitudes of mineral resources and the adequacy of these resources to meet future needs. In looking at global resource issues, we should consider the need for the resource, its supply, and the environmental consequences of using it. The need for a resource can become a resource dependency, specially as the global population expands and each of us becomes Increasingly dependent upon hundreds of natural materials. Therefore, our great mineral consumption makes the human population a true “Geologic Force”, which will be even more significant in the future when the global population is projected to reach alarming proportions. Although our supplies of mineral resources probably will be sufficient for the 21st century, the uneven distribution of minerals in the Earth's crust almost certainly will continue to be a major problem. The most likely result will be major shifts in both prices and sources of supply of many mineral resources. As for energy resources, we must avoid an obsessive dependency on one fuel and expand instead to other energy resources. Finally, because the use of resources affects the environment, we need to focus on resource exploitation and global pollution, particularly in regard to ground water and arable land. We must manage our resources so as to be in balance with our environment. And the accelerated industrialization of South Korean economy over the last three decades has resulted in the mass consumption of mineral commodities. South Korea has around 50 useful mineral commodities for the mineral industry, among 330 kinds of minerals described. The component ratio of the mining industry sector of the gross national production(GNP) in South Korea dropped from 1.2% in 1971 to 0.34% in 1997 due to the rapid growth of other industries in the country. During the period from 1971 to 1997, the average growth rate of mineral consumption in South Korea was 9.13% yearly and that of GMP per capita was 14.97%. The mineral consumptions per capita showed a continual increase during the last 30 years as follows(parenthesis: GW per capita); 0.99 metric tons in 1997($289), 3.83 metric tons in 1989($5, 210), 6.11 metric tons in 1995 ($10, 037), and 6.66 metric tons in 1997($9, 511). The total amount of mineral consumption in South Korea was 33 million tons of 32 mineral commodities in 1971, and 306 million metric tons of 47 mineral commodities in 1997.

• Membrane and Water Treatment
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• 제8권4호
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• pp.381-393
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• 2017

The inorganic components in tobacco sheet extract have significant influence on the sensory taste of the cigars and the harmful component delivery in cigarette smoke. To identify the contributions of the divalent inorganic components on harmful components delivery in cigarette smoke, a self-made selective electrodialysis was assembled with monovalent ion-selective ion exchange membranes. The influences of current density and extract content on the desalination performance were investigated. Result indicates that the majorities chloride, nitrate, and sulfate ions were removed, comparing with 50-60% of potassium and only less than 10% of magnesium and calcium ions removed in the investigated current density. The permselectivity of the tested cations across the Selemion CSO cation exchange membranes follows the order: $K^+>Ca^{2+}>Mg^{2+}$. A current density of $15mA/cm^2$ is an optional choice by considering both the energy consumption and separation efficiency. When the extract contents are in the range of 7%-20%, the removal ratios the potassium ions are kept around 60%, while the removal ratios of the calcium and magnesium ions fluctuate in the range of 16-27% and 8-14%, respectively. The tobacco smoke experiments indicated that the divalent metal ions have dual roles for the harmful component delivery in cigarette smoke. The divalent potassium and calcium ions were unfavorable for the total particulate matter emission but beneficial to decrease the HCN delivery in the mainstream cigarette smoke. The selective electrodialysis is a robust technology to decrease the harmful component delivery in cigarette smoke.

• 한국수자원학회논문집
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• 제31권3호
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• pp.317-326
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• 1998

시계열자료의 분해능력이 뛰어난 wavelet 변환을 사용하여 물소비특성을 분석하였다. Wavelet 변환의 기저함수로는 물수요량의 경우 Coiflets5 함수, 기온측정치의 경우 Coiflets3 함수를 사용하였으며 해석결과 212 scale에서 목표된 장기간에 걸친 변화추이는 hyperbolic tangent 함수의 형태로 전기간에 걸처 꾸준한 증가세를 보였다. 또한 절기혹은 경기주기와 밀접한 관련이 있을 것으로 생각되는 추가수요가 6월과 12월말을 정점으로 발생하였으며 이 추가 수요량은 하절기의 경우 $1,700\;\textrm{cm}^3/hr$, 동절기의 경우 $500\;\textrm{cm}^3/hr$ 정도인 것으로 관측되었다. 정수장 생산량 시계열자료에 내재한 주기성분은 주기가 각각 3.13day, 33.33 hr, 23.98hr와 12hr인 것으로 규명되었다. 진폭은 주기가 23,98hr인 성분이 가장 큰 것으로 밝혀졌으며 2i[i = 1,2,…12] scale에서 목도된 단주기성분들은 Gaussian PDF를 따르는 것이 확인되엇다. 잔차성분의 상호독립성, 자색파여부와 FPE의 최소화를 기준으로 할 경우 물수요량의 최적예측모형으로는 기온을 입력자료로한 다원 AR[32, 16, 23]과 다원 ARM [20, 16, 10, 23]인 것으로 판단된다.

• 전자공학회논문지D
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• 제35D권10호
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• pp.39-50
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• 1998

넓은 통과대역과 좁은 천이대역폭을 갖는 디지털 필터는 이동통신 장비의 CODEC이나 의료장비등에 사용된다. 이러한 주파수 특성을 갖는 디지털 필터는 다른 주파수 특성의 디지털 필터에 비해 계수 및 내부신호의 양자화 영향을 크게 받기 때문에 긴 워드 길이가 요구되며 이로 인해 칩의 면적 및 소모 전력이 증가한다. 본 논문에서는 이러한 주파수 특성을 갖는 디지털 필터의 저전력 구현을 위하여 CPL (Complementary Pass-Transistor Logic), 격자 웨이브 디지털 필터와 수정된 DIFIR (Decomposed & Interpolated FIR) 알고리듬을 이용한 설계 방법을 제시한다. CPL에서의 단락전류 성분을 줄이기 위하여 PMOS 몸체효과, PMOS latch 및 weak PMOS를 이용하는 3가지 방법에 대해 시뮬레이션을 통하여 비교한 결과 전파지연, 에너지 소모 및 잡음여유 면에서 PMOS latch를 사용하는 방법이 가장 유리하였다. 통찰력을 가지고 CPL 회로를 최적화하기 위해 CPL 기본구조에 대해 시뮬레이션 결과로부터 전파지연과 에너지 소모에 대한 경험식을 유도하여 트랜지스터의 크기를 정하는데 적용하였다. 또한 필터계수를 CSD (Canonic Signed Digit)로 변환하고 계수 양자화 프로그램을 이용하여 필터계수의 non-zero 비트수를 최소화시켜 곱셈기를 효율적으로 구현하였다. 알고리듬 측면에서 하드웨어 비용을 최소화하기 위해 수정된 DIFIR 알고리듬을 사용하였다. 시뮬레이션 결과 제안된 방법의 전력 소모가 기존 방법보다 38% 정도 감소되었다.