• 한국통신학회논문지
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• 제17권11호
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• pp.1320-1331
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• 1992

부분대역 간섭 환경하에서 m-분포 페이딩 채널을 통해 수신되는 반복다이버시티 방식의 FH/MFSK 신호에 대한 오율식을 유도하고 이를 수치계산하여 비트 에너지 대 잡음 전력 밀도 비 $(E_b/N_0)$, 비트에너지 대 간섭 전력 밀도 비 $(E_b/N_1)$, 페이딩 지수(m), 부분대역 간섭의 대역 점유율$(\rho)$, 반복 정송수(L), 신호와 간섭 사이의 전력 상관계수 값을 함수로 하여 그림으로 나타내고 이를 분석했다. 본 논문에서는 이동무선 채널에서 발생하는 페이딩에 대처하기 위해 송신기에서 반복 전송 다이버시티를 사용할 때를 생각했는데 다이버시티를 사용할 때와 사용하지 않을 때의 오율을 비교한 결과 반복 전송 다이버시티가 페이딩에 매우 효과적이라는 것을 알 수 있었으며 다이버 시티 기법에 의해 얻어지는 오율의 개선정도를 알아내었다. 얻어진 결과로 부터 부분대역 간섭의 대역 점유율인 $\rho$가 작아지면 작아질수록 오율이 열화되는 것으로 보아 전대역 간섭보다는 부분대역 간섭의 영향이 더 크다는 것을 알 수 있었다. 아울러 $E_b/N_1$가 작고 $\rho$가 작을때는 페이딩의 심도가 깊으면 깊을수록 반복다이버 시티를 도입하므로서 오율특성의 개선이 현저하다는 것도 알수 있었다.

• 한국해양공학회지
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• 제1권2호
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• pp.74-82
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• 1987

This study has been made to investigate into the behavior of fatigue limit, of fatigue crack initiation, and of fatigue crack propagation under the condition of rotating bending stress; specifically on the independency of stress field as well as the crack behavior of surface micro hole defect, which is made artificially through the specimen. The results obtained can be summarized as followa; 1) For the single micro hole defect, initiation of fatigue crack is occurred at both tips of microhole defect simultaneosly along the slip which are produced in the range of maximum principal stress arround micro hole defect independent of the size of micro hole defect. 2) For the neighbored deuble micro hole defects with equal size, in the range ($\frac{L}{r}$)ratio $\gtrsim$ 3 defined as the size of micro hole defect(2r) to the distance between the centers of micro hole defects (2L), the crack behavior of the micro hole defects is same as single one. However, for the range of $\frac{L}{r}$<3, the interference effect becomes significant as the ratio approaches to 1.

• Bulletin of the Korean Chemical Society
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• 제24권8호
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• pp.1177-1180
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• 2003

Thallium is quantitatively retained by 1,10-phenanthroline and tetraphenylborate onto benzophenone in the pH range 0-11 from a large volumes of aqueous solutions of various samples. After filtration, the solid mass consisting of thallium complex and benzophenone is dissolved with 5 mL of dimethylformamide and the metal was determined by flame atomic absorption spectrometric. About 0.4 ㎍ of thallium can be concentrated from 400 mL of aqueous sample, where its concentration is as low as 1.0 ng/mL. Eight replicate determinations of 8.0 ㎍/mL of thallium in final dimethylformamide solution gave a mean absorbance of 0.160 with a relative standard deviation of 1.7%. The sensitivity for 1% absorption was 0.22 ㎍/mL. The interference of a large number of anions and cations has been studied and the optimized conditions developed were utilized for the trace determination of thallium in various alloys and biological samples.

• 전자통신동향분석
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• 제38권1호
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• pp.55-64
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• 2023

Recently, preparations for 6G have led to the increasing interest in integrated or hybrid communication networks considering low-orbit satellite communication networks with terrestrial mobile communication networks. In addition, the demand for frequency allocation for new mobile services from low-orbit small satellites to provide global internet of things (IoT) services is increasing. The operation of such satellites and terrestrial mobile communication networks may inevitably cause interference in adjacent bands and the same band frequency between satellites and terrestrial systems. Focusing on the results of the recent ITU-R WP4C meeting, this study introduces the current status of frequency sharing and interference issues between satellites and terrestrial systems, and frequency allocation issues for new mobile satellite operations. Coexistence and compatibility studies with terrestrial IMT in L band and 2.6 GHz band, operated by Inmassat and India, respectively, and a new frequency allocation study (WRC-23 AI 1.18) are carried out to reflect satellite IoT demand. For the L band, technical requirements have been developed for emission from IMT devices at 1,492 MHz to 1,518 MHz to bands above 1,518 MHz. Related studies in the 2 GHz and 2.6 GHz bands are not discussed due to lack of contributions at the recent meeting. In particular, concerning the WRC-23 agenda 1.18 study on the new frequency allocation method of narrowband mobile satellite work in the Region 1 candidate band 2,010 MHz to 2,025 MHz, Region 2 candidate bands 1,695 MHz to 1,710 MHz, 3,300 MHz to 3,315 MHz, and 3,385 MHz to 3,400 MHz, ITU-R results show no new frequency allocation to narrow mobile satellite services. Given the expected various collaborations between satellites and the terrestrial component are in the future, interference issues between terrestrial IMT and mobile satellite services are similarly expected to continuously increase. Therefore, participation in related studies at ITU-R WP4C and active response to protect terrestrial IMT are necessary to protect domestic radio resources and secure additional frequencies reflecting satellite service use plans.

• 분석과학
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• 제13권1호
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• pp.121-126
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• 2000

이 연구의 목적은, 톨루엔에 노출된 근로자의 생물학적모니터링에 있어 혼재하는 유기산의 종류와 분석방법에 따른 요중 마뇨산 분석값을 비교하여, 다른 유기산이 혼재할 경우 UV법으로 분석했을 때 일어날수 있는 방해효과를 측정하는데 있다. 마뇨산만 포함된 소변 표준시료와 마뇨산, 메틸마뇨산, 페닐글리옥실산, 만델산 등 각각 다른 유기용제의 대사물이 포함된 소변 표준시료를 UV법, HPLC법으로 분석하고 유기산의 방해효과(IE; Inteference Efect)를 계산하였다. 또한 이들 소변 표준시료에 대해 전국 100개 검진기관을 대상으로 한 외부정도관리 결과, 참가기관들이 사용한 분석방법에 따른 요중 마뇨산 분석값을 비교하였다. 톨루엔과 크실렌에 노출된 근로자의 소변을 UV법으로 분석할 경우 크실렌 대사물인 메틸마뇨산은 마뇨산 분석값에 영향을 주어, 마뇨산 농도 0.33 g/L에서 0.5-2.0 g/L의 농도로 공존시 60-82%의 방해 영향을 가진 것으로 나타났다. 그러나 스티렌 대사물인 만델산, 페닐글리옥실산은 마뇨산 분석값에 거의 영향이 없었다. 따라서 톨루엔과 크실렌이 함께 노출되는 경우 소변 모니터링시 UV법을 사용하는 것보다 GC법이나 HPLC법을 사용하는 것이 바람직하다. 특히 특수검진기관의 의무 보유장비인 GC법은 경제적이고 신속하며 정확도가 높은 방법으로 UV법에 대체하여 사용할 수 있는 것으로 나타났다.

• 한국잡초학회지
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• 제32권1호
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• pp.17-24
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• 2012

The study was conducted to investigate the effect of weed interference and starter fertilizer on subsequent soybean seed quality at the Agricultural Research Farm and Laboratory of Razi University, Kermanshah, Iran. Two factorial experiment was laid-outon a randomized complete block design with four replications. First factor was starter fertilizer levels (0 and 25 kg $ha^{-1}$) applied in the forms of monoammonium phosphate, the second factor was different weed interference periods consisted of five initial weed-free periods (in which, plots were kept free of weeds for 0, 15, 30, 45 and 60 days after crop emergence (DAE) and then weeds were allowed to grow until harvest) and five initial weed-infested periods (in which, weeds were allowed to grow for 0, 15, 30, 45 and 60DAE, after which the plots were kept free of weeds until harvest). Full season weedy condition reduced 100-seed weight, seed germination percentage and seedling dry weight by 25.9, 13.3 and 22.5%, respectively and increased mean germination time and seed electrical conductivity by 55.8 and 24.3%, respectively as compared with full season weed-free control. However, the traits under study were not significantly influenced when field was kept free of weeds for at least 45 DAE (R1) or weedy condition was continued for less than 30 DAE (V8). There was a significant and negative correlation between weed biomass and seed weight (r = -0.93), so that when weed free condition was less than 45 DAE or weed infested period was continued for at least 30 DAE, soybean plants produced wrinkled and underdeveloped seeds with lower weights and qualities. Moreover, soybean seed quality reduction due to weed interference was more evident when starter fertilizer was applied and weeds interfered with soybean from the beginning of the growing season. Information from the present study is beneficial in soybean seed production systems and where farmers use the harvested seeds for the following planting.

• 한국소음진동공학회논문집
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• 제20권1호
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• pp.29-35
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• 2010

This paper studies causes of the L-1 blade damage of a low pressure turbine, which was found during the scheduled maintenance, in 500 MW fossil power plants. Many failures of turbine blades are caused by the coupling of aerodynamic forcing with bladed-disk vibration characteristics. In this study the coupled vibration characteristics of the L-1 turbine bladed-disk in a fossil power plant is shown for the purpose of identifying the root cause of the damage and confirming equipment integrity. First, analytic and experimental modal analysis for the bladed-disk at zero rpm as well as a single blade were performed and analyzed in order to verify the finite element model, and then steady stresses, natural frequencies and corresponding mode shapes, dynamic stresses were calculated for the bladed-disk under operation. Centrifugal force and steady steam force were considered in calculation of steady and dynamic stress. The proximity of modes to sources of excitation was assessed by means of an interference diagram to examine resonances. In addition, fatigue analysis was done for the dangerous modes of operation by a local strain approach. It is expected that these dynamic characteristics will be used effectively to identify the root causes of blade failures and to perform prompt maintenance.

• 한국광학회:학술대회논문집
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• 한국광학회 2001년도 제12회 정기총회 및 01년도 동계학술발표회
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• pp.34-35
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• 2001

The wavelength demultiplexer is an essential component in optical transmission systems using wavelength-division multiplexing(WDM), which can increase the number of channels and information capacity of optical fibers. For optical telecommunication, much attention has been given to demultiplexing two wavelengths in the 1.3${\mu}{\textrm}{m}$ of low dispersion band and 1.55${\mu}{\textrm}{m}$ of low loss window. Various integrated-optical devices have been proposed to perform this function, including conventional directional couplers, asymmetric Y-branching devices, asymmetric Mach-Zehnder interferometers and two-mode interference devices. (omitted)

• 음성과학
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• 제12권4호
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• pp.113-128
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• 2005

The underlying premise of this study was that L1 production is easily transferred into L2 production. In neutral intonation, there is a consonant-tone correlation in Korean: High tone patterns are correlated with voiceless aspirated and tense consonants and Low-High tone patterns are correlated with lax or other voiced consonants. The purpose of this study was to see whether the correlation in Korean (L1) is transferred into English (L2) production and whether the degree of transfer differs depending on the degree of proficiency. Eight Korean speakers and two American speakers participated in the experiment. F0 contours of words and sentences were collected and analyzed. The results of the present study showed that there is a strong correlation between voicing and tone in L2 utterances. When utterance-initial consonant types were voiceless, the word or the sentence began with the H pattern; otherwise it had the LH pattern. The degree of interference differed depending on the degree of proficiency: less proficient speakers showed a stronger correlation in terms of the magnitude (Hz) and size (ms) of the effects on F0. The results indicate that the consonant-tone correlation in L1 is strongly transferred into L2 production and the correlation transfer can be one of the actual aspects that cause L2 speakers to produce deviant L2 accents and intonation.

• 한국조경학회지
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• 제30권6호
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• pp.38-46
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• 2003

Perceived crowding is known as a necessary method to evaluate social carrying capacity in recreational settings. But according to the results of previous research, perceived crowding, use density, and satisfaction have shown weak and indirect correlations. The theory of visitors’ adjustment is one of several possible explanations for this poor relation. But the validity of the visitors’ adjustment theory has not been not inspected clearly. Therefore, the purposes of this study are to understand visitors’ adjustment theory and to examine visitors’ adjustment to the overuse of recreational settings. Study hypotheses were formulated through literature review and related to visitors’ adjustment in recreation density. Pour hypotheses were established and inspected with the case study, i.e., Rationalization : Visitors’ satisfaction isn't related to use density in recreation setting, 2) Product-shift : Preference norm is related to current use density, 3) Self-selection : Visitors’ satisfaction for the use level is generally high, and 4) Displacement : Norm interference is related to willingness to revisit. The case study was conducted during May and June,2001. According to the results of this survey, visitors adjust to overuse of recreation setting through rationalization and product shift (hypotheses l/2 acceptance). Current use density isn't related to visitors’ satisfaction and willingness to revisit (see table 3). And visitors’ preference norm is modified by situation (see table 4). Visitors’ satisfaction and willingness to revisit don't show a high correlation but moderately high (see table 5, hypothesis 3 acceptance). Differences between visitors’ preference norm and current use density is norm interference. Norm interference isn't related to willingness to revisit (see table 7). Therefore, the norm interference concept is not a useful method to explain visitors’ adjustment to the degree of overuse in a recreational setting (hypothesis 4 rejection). As for future directions, the following are proposed: 1) correctly understanding and reestablishing the visitor norm and norm interference concept, 2) introducing a composite research method to monitor visitors’ behavior and survey visitors’ attitudes and coping responses. These efforts would be helpful in the Planning and management of recreational settings to improve the quality of visitors’ experiences.