• 제목/요약/키워드: III/V ratio

검색결과 226건 처리시간 0.025초

Band-III T-DMB/DAB 모바일 TV용 저전력 CMOS RF 튜너 칩 설계 (Design of a Fully Integrated Low Power CMOS RF Tuner Chip for Band-III T-DMB/DAB Mobile TV Applications)

  • 김성도;오승엽
    • 한국전자파학회논문지
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    • 제21권4호
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    • pp.443-451
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    • 2010
  • 본 논문에서는 Band-III 지상파 디지털 멀티미디어 방송 수신용 저전력 CMOS RF 튜너 칩에 대해 기술한다. 제안된 RF 튜너 칩은 저전력의 소형 휴대단말기 개발에 적합한 Low-IF 수신 구조로 설계되었으며, 174~240 MHz의 RF 방송 신호를 수신하여 1.536 MHz 대역폭의 2.048 MHz IF 신호를 출력한다. RF 튜너 칩은 저잡음 증폭기, 이미지 신호 제거 믹스, 채널 필터, LC-VCO, PLL과 Band-gap 기준 전압 생성기 등의 모든 수신부 기능 블록들을 포함하고 있으며, 0.18 um RF CMOS 기술을 이용하여 단일 칩으로 제작되었다. 또한 전력 소모를 줄이기 위한 4단계 이득 가변이 가능한 저잡음 증폭기를 제안하였으며, Schmoock's 선형화 기법과 Current bleeding 회로 등을 이용하여 수신 성능을 개선하였다. 제작된 RF 튜너 칩의 이득 제어 범위는 -25~+88 dB, 잡음 특성(NF)은 Band-III 전체 대역에서 약 4.02~5.13 dB, 선형 특성(IIP3)은 약 +2.3 dBm 그리고 이미지 신호 제거비는 최대 63.4 dB로 측정되었다. 총 전력 소모는 1.8 V 단일 전원에서 약 54 mW로 우수하며, 칩 면적은 약 $3.0{\times}2.5mm^2$이다.

일축압축하에서 포천화강암의 역학적 이방성 (Mechanical Anisotropy of Pocheon Granite under Uniaxial Compression)

  • 박덕원
    • 지질공학
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    • 제15권3호
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    • pp.337-348
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    • 2005
  • 포천 지역에 분포하는 쥬라기 화강암을 대상으로 미세균열 분포특성이 화강암의 역학적 성질에 미치는 영향에 대하여 연구하였다. 3종의 방향성 시편을 대상으로 일축압축시험이 실시되었으며, 각 시편은R(riftplane), G(grain plane) 및 H(hardway plane) 축에 각각 직각이다. 다양한 탄성 상수 중, 3 방향에 따른 포아송비의 변화가 검토되었다 파괴 강도 비-포아송비의 관계도에서 포아송비의 범위는 H-시편에서 가장 높은 분포양상을 보이며 G-시편, R-시편의 순으로 감소한다. 분포곡선은 $I\simIII$ 단계에서는 거의 선형이며, IV-3 단계에서는 기울기의 급격한 증가를 보인다. 관계도에서 보는바와 같이 파괴강도비 $0.92\sim0.96$에서 변곡점이 형성된다. IV-3단계는 탄성 영역의 밖에 속한다. 4단계의 파괴단계에서의 거동은 응력-체적변형율 곡선에서 분석되었다 암석의 거동을 지배하는 응력증분-체적변형율 방정식에서 특징적인 재료상수인 a, n, Q, m 및 $\varepsilon_v^{mcf}$가 결정되었다. 이들 상수중에서 미세균열의 폐합영역( I 단계)에서 고유의 미세균열의 공극률$(a, 10^{-3})$ 그리고 압축지수(n)는 각각 $a^R(3.82)>a^G(3.38)>a^H(2.32)$ 그리고 $n^R(3.69)>n^G(2.79)>n^H(1.99)4의 순서로 나타난다. 특히 IV 단계의 미세균열의 임계체적변형율($\varepsilon_v^{mcf}$)은 3번 면에 수직인 H-시편에서 가장높게 나타난다. 이러한 결과에서 포아송비 및 재료상수와 같은 역학적 성질은 2 조의 미세균열과 밀접한 관계를 보이고있다. 강도 이방성과 미세균열의 방향성과의 상관성은 암석의 파괴 연구에 주요하게 적용될 수 있다.

뇌졸중(腦卒中)에 관(關)한 임상통계적(臨床統計的) 연구(硏究) (Clinical Observation on C.V.A.)

  • 윤진구;조기호;김영석;이경섭
    • 대한한방내과학회지
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    • 제10권1호
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    • pp.25-38
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    • 1989
  • Clinical observation was done on 1092 cases of cerebrovascular disease which were confirmed by Brain CT scan in Oriental Medical Hospital in Kyung Hee Univ. from May 1987 to May 1988. Specially, clinical prognosis of 250 patients who had been hospitalized for over 4 weeks, were obserbed. The results were obtained as follows; 1. In this study, Occlusive CVD was 77.9%, Cerebral hemorrhage was 18.8%, Subarachnoid hemonhage was 0.8%. 2. The ratio of male to female was 1.4:1. In the age distribution, 60th decade, 50th decade, 40th decade, 30th's, 20th's were in order of frequency and specially 60th decade was 35.53% over 70th decade was 17.1% in ratio. 3. The most common preceding disease of CVD was hypertension (54.21%) and diabetes mellitus (19.96%) was second. 4. Almost, the duration of hospitalization was 2-4 weeks in 34.8%, within 4 weeks in 78.02%. 5. Primary attack was 75.7%, 2nd attack was 17.9%, over 3rd attack was 3.1% in ratio of recurrence. 6. The level of consciousness was Grade I in 96.4%, Grade II in 3.2%, Grade III in 1% at attack. 7. A few complications of C.V.A. were observed in the studies: pneumonia was noted frequently in 3.2%, bed sore, urinary tract infection, gastro intestinal bleeding in order of frequency. 8. The ratio of neurologic deficiency in occlusive CVD decreased from 51.9% to 29.3% in upper limb, 52.6% to 24.4% in lower limb, and that in cerebral hemorrhage decreased from 69.5% to 25% in upper limb, 50% to 20% in lower limb. 9. The ratio of left side hemiplegia to right was 1.04:1 in male, 1:1.18 in female. 10. The herb medications for C.V.A. were various Chungg-Paesagantang, Sunghanggeonggisan were used most frequently to Chungyeold, Geopung, Soongi, Haldam and Chungsimtang, the drugs for Bogiheol were used as discharge. In these oriental medical therapy of C.V.A. objective diagnosis and more various therapeutic method must be obtained through east-west medical co-operation.

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A New Species of Farranula (Copepoda: Cyclopoida: Corycaeidae) from the West Central Pacific, with a Key to Species of the Genus

  • Wi, Jin Hee;Soh, Ho Young;Jeong, Hyeon Gyeong;Kang, Hyung-Ku
    • Animal Systematics, Evolution and Diversity
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    • 제31권1호
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    • pp.31-41
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    • 2015
  • A new species of the genus Farranula Wilson, 1942 (Cyclopoida, Corycaeidae) is described based on both sexes collected off Chuuk Island in Micronesia (West Central Pacific). The new species F. dahlae differs from its close congener F. gibbula (Giesbrecht, 1891) in the following combination of characters in both sexes: body length is longer, length to width ratio of caudal rami is larger, basal element of maxilliped is distinctly longer, and terminal spine to distal segment ratio of P4 is smaller; while in females, lateral margins of fourth pedigerous somite are extended to mid-region of second urosomal somite, maximum width of the second urosomal somite is located at middle region in dorsal and lateral views, and length ratio of caudal seta III to seta V is much larger; and in males, sharply contracted portion of second somite is located at two-thirds distance from anterior margin. Some additional morphological details of F. gibbula are given and a key to species of the genus Farranula is provided.

산느타리(Pleurotus pulmonarius) 병·봉지재배에 적합한 배지조성 연구 (Study on suitable substrate formulation for bottle and bag cultivation of Pleurotus pulmonarius)

  • 이재홍;이남길;박영학;문윤기;정태성;권순배;김재록;김진원
    • 한국버섯학회지
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    • 제12권4호
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    • pp.275-279
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    • 2014
  • 산느타리를 안정적으로 생산할 수 있는 배지를 개발하기 위하여 미루나무톱밥, 면실피, 면실박, 비트펄프, 콘코브 등 5종을 혼합하여 혼합비율별 6처리로 시험을 수행하여 배지조성별 화학성분, 균사생장속도 및 수량특성을 조사하였다. 배지조성별 화학성분 분석결과 pH는 대부분 pH 5.0 내외로서 큰 차이가 없었으나, V배지의 경우 다른 조성에 비하여 pH와 유기물 함량에 있어 각각 5.52, 29.07%로 높게 나타났다. 유기물대질소비는 IV배지가 30.53으로 가장 높았고, I, V, VI배지가 25정도를 나타냈으며, II, III배지는 20.68, 22.12로 낮은 값을 나타냈다. 시험관 칼럼배지를 이용해서 균사생장속도를 조사한 결과 균접종 28일 조사에서 향산 품종에서는 V배지가 105.0 mm로 가장 빠른 생장을 나타냈고, 호산 품종에서는 II번 배지가 114.3 mm로 가장 빨랐다. 병재배시 배지조성별 생육특성 조사결과 초발이소요일수는 3일, 생육일수는 4일로 모든 처리에서 동일하였고, 수량에 있어서는 호산품종의 경우 V배지가 병당 유효경수가 19.1개, 병당 수량이 198.4 g으로 가장 높은 수치를 나타냈으며, 향산 품종에서는 IV배지와 V배지가 각각 유효경수 15.3개, 14.4개, 수량은 161.1 g, 163.1 g으로 비슷하였다. 봉지재배에서 호산품종의 경우 초발이소요일수는 IV배지가 7일로서 가장 빨랐고 다음이 V, VI배지로서 8일, 그 다음이 I배지 9일 순이었다. 향산 품종에서 초발이소요일수는 I배지가 6일로서 가장 빨랐고 다음으로 IV, VI, V배지 순이었다. 그리고 생육일수는 4내지 5일로서 품종별, 배지조성별 차이가 없었다. 수량특성 조사결과 호산 품종의 경우 I배지가 봉지당 435.7 g으로 가장 높았고, 향산 품종에 있어서는 V배지가 463.5 g으로 높은 수량을 나타냈다.

Effect of dissimilar metal SENB specimen width and crack length on stress intensity factor

  • Murthy, A. Ramachandra;Muthu Kumaran, M.;Saravanan, M.;Gandhi, P.
    • Nuclear Engineering and Technology
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    • 제52권7호
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    • pp.1579-1586
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    • 2020
  • Dissimilar metal joints (DMJs) are more common in the application of piping system of many industries. A 2- D and 3-D finite element analysis (FEA) is carried out on dissimilar metal Single Edged Notch Bending (DMSENB) specimens fabricated from ferritic steel, austenitic steel and Inconel - 182 alloy to study the behavior of DMJs with constraints by using linear elastic fracture mechanics (LEFM) principles. Studies on DMSENB specimens are conducted with respect to (i) dissimilar metal joint width (DMJW) (geometrical constraints) (5 mm, 10 mm, 20 mm, 30 mm and 50 mm) (ii) strength mismatch (material constraints) and (iii) crack lengths (16 mm, 20 mm and 24 mm) to study the DMJ behavior. From the FEA investigation, it is observed that (i) SIF increases with increase of crack length and DMJWs (ii) significant constraint effect (geometry, crack tip and strength mismatch) is observed for DMJWs of 5 mm and 10 mm (iii) stress distribution at the interfaces of DMSENB specimen exhibits clear indication of strength mismatch (iv) 3-D FEA yields realistic behavior (v) constraint effect is found to be significant if DMJW is less than 20 mm and the ratio of specimen length to the DMJW is greater than 7.4.

A Novel Iron(III) Selective Membrane Electrode Containing a Tripodal Polycatacholamine as Sensor

  • Bera, Rati Kanta;Sahoo, Suban K;Baral, Minati;Kanungo, B.K.
    • Bulletin of the Korean Chemical Society
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    • 제32권10호
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    • pp.3592-3596
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    • 2011
  • A novel poly(vinylchloride)-based membrane sensor using $N^1$,$N^3$,$N^5$-tris(2-(2,3-dihydroxybenzylamino)-ethyl)cyclohexane-1,3,5-tricarboxamide (CYCOENCAT, L) as ionophore has been prepared and explored as $Fe^{3+}$ selective electrode. The membrane electrode composed of ionophore, poly(vinylchloride) and o-nitropheyloctyl ether in the optimum ratio 4:33:63 gave excellent potentiometric response characteristics, and displayed a linear log[$Fe^{3+}$] versus EMF response over a wide concentration range of $1.0{\times}10^{-5}-1.0{\times}10^{-1}$ M with super nernstian slope of 28.0 mV/decade and the detection limit of $8.0{\times}10^{-6}$ M. The proposed ion selective electrode showed fast response time (< 15 s), wide pH range (3.0-7.0), high non-aqueous tolerance (up to 20%) and adequate long life time (120 days). It also exhibited very good selectivity for $Fe^{3+}$ relative to a wide variety of alkali, alkaline earth, transition and heavy metal ions. Further, the analytical applicability of the sensor was tested as an indicator electrode in the potentiometric titration of $Fe^{3+}$ with EDTA.

평행식 진동탄환 암거 천공기의 연구(III)-견인력, 토크, 동력 및 모멘크에 관한 모형시험- (A Study on Balanced -type Oseillating Mole-Drainer(III)-Model Test for Draft Force, Torque, Power and Moment)

  • 김용환
    • Journal of Biosystems Engineering
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    • 제1권1호
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    • pp.1-6
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    • 1976
  • This paper is the third one of the study on balanced type oscillating mole-drainer, the first one was presented in No 9. Gyeongsang College Report and the second one in Vol. 17, No.4 of the KSAE. In the first part of this study, the characteristics of traction forces between the nonoscillating earth working equipments and oscillating ones was compared. A model of the balanced type oscillating mole-drainer, which composed of a mechanism that may reduce the machine vibration, was designed following the dimensional analysis and similitude technique. The model test was carried out to clarify the balancing mechanism of the oscillating parts and other parts of the machine. In the light of the results from the model tests, a prototype machine was made for experimental purpose. Results from the field test by a reported in the near future. In the second report, the model tests were carried out under the same soil conditions, i.e, . oscillating frequency, running velocity, and oscillating amplitude, etc. It was clear that use of balanced type oscillating model could substantially reduce the vibration of the whole system of the machine, when compared with the nonoscillating type model. In this paper(the third report), results of investigation on the traction force, power requirement, and moment. etc, is presented. Analysis of variance technique was used for analyzing the effect of the frequency, amplitude, and running velocity on the draft force, torque, power requirements, and moments. The results obtained from the model tests are as follows, 1) By practicing a balanced-type oscillating mole-drainer, it was possible to reduce the traction resistance by 55.1-61. 2 percent of traction resistance, however, was 1.75 - 1.95 times greater than the value of resistance which was induced by use of a mole-drainer with single bullet. The resistance of rear shank against soil was considered as a main causing factor of the above results. 2) As the oscillation frequency was increased, the traction resistance was decreased. Considering on the effect of oscillation the greater the amplitude, and the slower the running velocity was, the greater the reduction ratio of traction resistance was. 3) The ratio of the traction resistance of oscillating mole-drainer to that of non-oscillating one could be represented as a function of dimensionless variable (V/$Af$). The results from the tests were well agreed with the reported results from the experim ents on oscillation plow or hoe. 4) By taking a lower value of (V/$Af$), reducing the traction resistance was possible. This fact meant, however, that the efficiency of mole drain practice would be lower. 5) It was experimentally confirmed under the same condition of soil that the variable (R/$rD1^3$) could be represented as a function of a variable($V^2/gD$) when a non\ulcornerocillating mole-drainer was used. 6) When a oscillating mole-drainer was used, the variable(R/$rD_1^{3}$) could be represented as a function of two variables ($v^2/gD_1$) and (V^2/gD_1$). 7) The torque was not affected by a change of frequency. However, a relation of proportionality existed between torque and amplitude, running velocity, and ratio of bullet diameter. When a balanced type oscillating mole-drainer with two bullets was used, torque was increased by 52.8-78. 4 percent and total power requirement was also increased. 8) Total power requirement was increased linearly in accordance with the increasing frequency, 41.96 percent of total power was used for oscillating action. The magnitude of total power requirement was 1. 8-9. 4 times greater than that of a non-oscillating mechanism. In the view point of power requirement, it was not advisable to increase the frequency, amplitude, running velocity, and ratio of bullet diameter at the same time. 9) Only the positive moment occured in the rear shank. Change of the diameter of a rear bullet, could not affect the balancing against the soil resistance. It was necessary for rear bullet to have a large resistance against soil only when the rear bullet was in backward motion. 10) Within an extent of the experimental base, optimum limits for several design factors were A=0.5cm, $f$=22.5Hz, V=O. 05m/sec, and $\lambda$=1.0 By adapting these values traction resistance was reduced by 40 percent and vibration acceleration wa s reduced by 60 percent. Even though the total , power requirements for operating a balanced type oscillation mechanism was greater ~than that of non-oscillating one, using a oscillating mechanism would be more effective. Because a balanced type oscillating mechanism is used, tractive resistance will be reduced and then the lighter . tractive equipment could be used.

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The recombination velocity at III-V compound heterojunctions with applications to Al/$_x$/Ga/$_1-x$/As-GaAs/$_1-y$/Sb/$_y$/ solar cells

  • 김정순
    • 전기의세계
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    • 제28권4호
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    • pp.53-63
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    • 1979
  • Interface recombination velocity in $Al_{x}$G $a_{1-x}$ As-GaAs and $Al_{0.85}$, G $a_{0.15}$ As-GaA $s_{1-y}$S $b_{y}$ heterojunction systems is studied as a function of lattice mismatch. The results are applied to the design of highly efficient III-V heterojunction solar cells. A horizontal liquid-phase epitaxial growth system was used to prepare p-p-p and p-p-n $Al_{x}$G $a_{1-x}$ As-GaA $s_{1-y}$S $b_{y}$-A $l_{x}$G $a_{1-x}$ As double heterojunction test samples with specified values of x and y. Samples were grown at each composition, with different GaAs and GaAs Sb layer thicknesses. A method was developed to obtain the lattice mismatch and lattice constants in mixed single crystals grown on (100) and (111)B oriented GaAs substrates. In the AlGaAs system, elastic lattice deformation with effective Poisson ratios .mu.$_{eff}$ (100=0.312 and .mu.$_{eff}$ (111B) =0.190 was observed. The lattice constant $a_{0}$ (A $l_{x}$G $a_{1-x}$ As)=5.6532+0.0084x.angs. was obtained at 300K which is in good Agreement with Vegard's law. In the GaAsSb system, although elastic lattice deformation was observed in (111) B-oriented crystals, misfit dislocations reduced the Poisson ratio to zero in (100)-oriented samples. When $a_{0}$ (GaSb)=6.0959 .angs. was assumed at 300K, both (100) and (111)B oriented GaAsSb layers deviated only slightly from Vegard's law. Both (100) and (111)B zero-mismatch $Al_{0.85}$ G $a_{0.15}$As-GaA $s_{1-y}$S $b_{y}$ layers were grown from melts with a weight ratio of $W_{sb}$ / $W_{Ga}$ =0.13 and a growth temperature of 840 to 820 .deg.C. The corresponding Sb compositions were y=0.015 and 0.024 on (100) and (111)B orientations, respectively. This occurs because of a fortuitous in the Sb distribution coefficient with orientation. Interface recombination velocity was estimated from the dependence of the effective minority carrier lifetime on double-heterojunction spacing, using either optical phase-shift or electroluminescence timedecay techniques. The recombination velocity at a (100) interface was reduced from (2 to 3)*10$^{4}$ for y=0 to (6 to 7)*10$^{3}$ cm/sec for lattice-matched $Al_{0.85}$G $a_{0.15}$As-GaA $s_{0.985}$S $b_{0.015}$ Although this reduction is slightly less than that expected from the exponential relationship between interface recombination velocity and lattice mismatch as found in the AlGaAs-GaAs system, solar cells constructed from such a combination of materials should have an excellent spectral response to photons with energies over the full range from 1.4 to 2.6 eV. Similar measurements on a (111) B oriented lattice-matched heterojunction produced some-what larger interface recombination velocities.ities.ities.s.

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선택적 에피 성장법에 의한 GaAs/AIGaAs 다층구조 및 InGaAs/GaAs 양자세선의 성장 및 photoluminescence 연구 (Selectively Grown ALGaAs/GaAs Multilayers and InGaAs/GaAs Quantum Wire Structures Grown by Low Pressure MOCVD)

  • 김성일;김영환
    • 한국진공학회지
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    • 제12권2호
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    • pp.118-122
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    • 2003
  • 저압 MOCVD 장치를 이용하여 선택적 에피 성장 (selective area epitaxy) 기술을 개발하고, 이 기술을 이용하여 InGaAs/GaAs 양자세선(quantum wire) 구조를 성장하였다. $SiO_2$로 선택적으로 마스킹 된 GaAs 기판위에 AIGaAs/GaAs 다충 구조 및 InGaAs/GaAs 양자세선 구조를 저압 MOCVD 방법으로 성장하였다. 매끄러운 사면을 갖고 끝 부분이 뽀쪽한 삼각형 구조의 양자세선 구조가 선택적 에피 성장법에 의해 자발적으로 형성되었다. 선택적 에피층 성장을 위한 최적 조건을 알기 위해 먼저 GaAs/AlGaAs 다층구조에 대하여 여러 가지 성장변수들에 대하여 조사하였다. 성장 변수들은 성장률(growth rate), V/III 비 및 성장온도, 패턴의 정렬 방향 등이다. 양자세선에서 나오는 발광은 975 nm로 분석되었다. 측정 온도가 증가됨에 따라 삼각형 구조의 사면의 양자우물에서 나오는 발광은 급격하게 감소하였다. 그러나 양자세선에서 나오는 발광은 양자우물에서 나오는 발광에 비해 서서히 감소하였고, 50 K 이상의 온도에서는 양자세선에서 나오는 발광의 세기가 더 커졌다.