숙박시설의 조건이 여행 상품 기획자의 숙박시설 선택에 미치는 영향

정명준 한국호텔외식관광경영학회 2015 한국호텔외식경영학회 학술발표논문집 Vol.- No.-

대역 분할 처리를 통한 데몬 처리 성능 향상 기법

정명준,황수복,이승우,김진석,Cheong, Myoung Jun,Hwang, Soo Bok,Lee, Seung Woo,Kim, Jin Seok 한국음향학회 2013 韓國音響學會誌 Vol.32 No.2

수동 소나는 데몬 처리를 통해 수중 표적의 방사 소음으로부터 프로펠러 정보를 분석한다. 기존 데몬 처리 기법은 신호대 잡음비(Signal to Noise Ratio)를 높이기 위해 시간 영역에 대해 음향 신호를 분할하여 중첩 처리하는 방법을 사용하였다. 다시 말해 일정 시간동안 음향 신호를 수집 및 분할 처리 후 평균을 취해 잡음의 분산(variance)을 감소시켜 신호대 잡음비를 향상시켰다. 그러나 이러한 방법은 각 처리 구간의 음향 신호가 서로 독립적이지 않아 높은 성능 향상을 위해서는 많은 시간과 연산량이 필요하다. 따라서 본 논문에서는 대역 분할 처리를 통한 데몬 처리 성능 향상 기법을 제안한다. 제안된 기법은 주파수 영역에서 음향 신호의 구간을 분할하여 데몬 처리를 수행하므로 기존 중첩 기법에 비해 짧은 시간안에 서로 독립적 음향 신호 수집이 가능하다. 따라서 기존 기법에 비해 적은 시간과 연산량으로 동일한 성능을 발휘할 수 있다. 제안된 기법은 수학적 분석 및 시뮬레이션을 통해 기존 기법에 비해 성능이 우수함을 검증하였다. Passive sonars employ DEMON (Detection of Envelope Modulation on Noise) processing to extract propeller information from the radiated noise of underwater targets. Conventional DEMON processing improves SNR(Signal to Noise Ratio) characteristic by Welch method. The conventional Welch method overlaps several different time domain DEMON outputs to reduce the variance. However, the conventional methods have high computational complexity to get high SNR with correlated acoustic signals. In this paper, we propose new DEMON processing method that divides acoustic signal into several frequency bands before DEMON processing and averages each DEMON outputs. Therefore, the proposed method gathers independent acoustic signal faster than conventional method with low computational complexity. We prove the performance of the proposed method with mathematical analysis and computer simulations.

CCOA와 FDAM marker를 이용한 전통 수록지의 열화 특성 평가

정명준,조병묵,정소영,( Antje Potthast ) 韓國木材工學會 2008 한국목재공학회 학술발표논문집 Vol.2008 No.-

다결정 SnSe 열전 재료의 성능 개선 연구 동향

정명준,최병준 한국분말재료학회 2022 한국분말재료학회지 (KPMI) Vol.29 No.2

Thermoelectric materials can reversely convert heat and electricity into each other; therefore, they can be very useful for energy harvesting from heat waste. Among many thermoelectrical materials, SnSe exhibits outstanding thermoelectric performance along the particular direction of a single crystal. However, single-crystal SnSe has poor mechanical properties and thus it is difficult to apply for mass production. Therefore, polycrystalline SnSe materials may be used to replace single-crystal SnSe by overcoming its inferior thermoelectric performance owing to surface oxidation. Considerable efforts are currently focused on enhancing the thermoelectric performance of polycrystalline SnSe. In this study, we briefly review various enhancement methods for SnSe thermoelectric materials, including doping, texturing, and nano-structuring. Finally, we discuss the future prospects of SnSe thermoelectric powder materials.

회전형 원자층 증착기의 회전 속도에 따른 SnSe 분말 상 ZnO 박막 증착

정명준,윤예준,변종민,최병준,Jung, Myeong Jun,Yun, Ye Jun,Byun, Jongmin,Choi, Byung Joon 한국분말재료학회 (*구 분말야금학회) 2021 한국분말재료학회지 (KPMI) Vol.28 No.3

The SnSe single crystal shows an outstanding figure of merit (ZT) of 2.6 at 973 K; thus, it is considered to be a promising thermoelectric material. However, the mass production of SnSe single crystals is difficult, and their mechanical properties are poor. Alternatively, we can use polycrystalline SnSe powder, which has better mechanical properties. In this study, surface modification by atomic layer deposition (ALD) is chosen to increase the ZT value of SnSe polycrystalline powder. SnSe powder is ground by a ball mill. An ALD coating process using a rotary-type reactor is adopted. ZnO thin films are grown by 100 ALD cycles using diethylzinc and H₂O as precursors at 100℃. ALD is performed at rotation speeds of 30, 40, 50, and 60 rpm to examine the effects of rotation speed on the thin film characteristics. The physical and chemical properties of ALD-coated SnSe powders are characterized by scanning and tunneling electron microscopy combined with energy-dispersive spectroscopy. The results reveal that a smooth oxygen-rich ZnO layer is grown on SnSe at a rotation speed of 30 rpm. This result can be applied for the uniform coating of a ZnO layer on various powder materials.

제지용 섬유의 Carboxymethyl화 및 Carbamoylethyl화에 의한 sheet의 습윤강도 향상

정명준,권오철,조병묵,오정수 동국대학교 생명자원과학대학 연습림 2000 연습림논문집 Vol.- No.6

Paper has been an essential part of our civilization for at least two thousand years and we can get various functional paper given by the treatment of coating, laminating, blending and addition of chemicals. Above all, wet strength paper is an important group of other grade paper. Certain paper require a wet strength in order to maintain their properties under wet or humidity conditions. For the purpose of improving the wet strength properties of paper, cellulose fiber was modified by the process of carbamoylethylation and carboxy- methylation. We have the carbamoylethylation of cellulose fiber reacted with acryl- amide in alkali catalyst and carboxymethylation of cellulose fiber reacted with mono- chloroacetic acid in alkali catalyst. The N-chlorocarbamoylethylated sheet and combined sheet of carboxymethylated and carbamoylethylated cellulose fiber more effect than untreated sheet in dry strength. As for folding endurance, the combination of carboxymethylated cellulose fiber and carbamoylethylated cellulose fiber sheet were more effective than other modified fibers. The combination of carboxymethylated cellulose fiber and carbamoylethylated cellulose fiber sheet has some effect on wet tensile strength, but this sheet it less effective than N-chlorocarbamoylethylated sheet.

불연속적인 다중 주파수 측정치에 강인한 표적기동분석 알고리즘

정명준,Cheong, Myoung-Jun 한국군사과학기술학회 2011 한국군사과학기술학회지 Vol.14 No.3

Estimating underwater target state variables(position, velocity, course, etc) is necessary to counteract threatening targets. In passive sonar systems, conventional target motion analysis(TMA) techniques using bearing and frequency measurements of an underwater target are widely introduced. However, it is not clear how conventional TMA techniques can be used if some of frequency measurements are unavailable during parts of the scenario, partially unavailable frequency measurements are common in the ocean with complicated acoustic conditions where frequency measurements often come and go. This paper proposes a new TMA algorithm, which is robust to partially unavailable frequency measurements, using the frequency measurements fusion method.

Changes in the Structure of Cellulose Aerogels with Depolymerization

정명준,이신아,강규영,Antje Potthast 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.4

To compare the cellulose aerogels from hydrolyzed and unhydrolyzed cotton linter, we prepared cellulose wet gels from cellulose solution dissolved in hydrated calcium thiocyanate at 110 C and dried them by using the freeze-drying method. The initial root-mean-square (RMS) radius and the weight average molar mass of cotton linter decreased from 71 nm and 405 kg·mol−1, respectively, to 13 nm and 35 kg·mol−1 upon acid hydrolysis. The density of cellulose aerogels increased from 39 to 87 kg/m3 as the cellulose starting material was depolymerized. The microstructure of the cellulose aerogel was viewed with a scanning electron microscope (SEM), and the microstructure and the micro-sized pores were found to be destroyed by cellulose degradation. The degree of polymerization (DP) of the cellulose was found to affect the aerogel’s density and network structure.

SEC-MALLS를 이용한 셀룰로오스 원료의 품질 분석 및 응용

정명준 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

현대과학기술의 발달에 따라 고분자의 분자량을 평가하기 위하여 다양한 방법들 역시 발전해왔다. 그 중 size-exclusion chromatography-multi angle laser light scattering (SEC-MALLS) 기술의 발달에 따라 셀룰로오스와 같은 선형 고분자뿐 만 아니라 헤미셀룰로오스와 같은 측쇄를 가진 천연고분자의 절대분자량 측정이 가능하게 되었다. 이와 같은 SEC-MALLS에 의한 절대분자량 측정은 셀룰로오스계 물질 자체의 품질 관리뿐 만 아니라 각종 셀룰로오스 유도체의 중합도에 따른 치환도 평가와 가교결합에 따른 응집 거동 분석이 가능하게 되었으며, 더 나아가 다양한 셀룰로오스의 산화정도와 가수분해속도를 평가하여 셀룰로오스계 지류문화재의 보존 상태와 앞으로의 기대수명 평가에도 활용이 가능하다. **본 연구는 한국연구재단 '신진연구지원사업(과제번호: NRF-2014R1A1A1007624)'의 지원에 의해 수행되었습니다.

로터리형 원자층 증착법을 이용한 Bi-Te계 소결체의 열전 성능 개선

정명준,박지영,은수민,최병준 한국분말재료학회 2023 한국분말재료학회지 (KPMI) Vol.30 No.2

Thermoelectric materials and devices are energy-harvesting devices that can effectively recycle waste heat into electricity. Thermoelectric power generation is widely used in factories, engines, and even in human bodies as they continuously generate heat. However, thermoelectric elements exhibit poor performance and low energy efficiency; research is being conducted to find new materials or improve the thermoelectric performance of existing materials, that is, by ensuring a high figure-of-merit (zT) value. For increasing zT, higher σ (electrical conductivity) and S (Seebeck coefficient) and a lower к (thermal conductivity) are required. Here, interface engineering by atomic layer deposition (ALD) is used to increase zT of n-type BiTeSe (BTS) thermoelectric powders. ALD of the BTS powders is performed in a rotary-type ALD reactor, and 40 to 100 ALD cycles of ZnO thin films are conducted at 100oC. The physical and chemical properties and thermoelectric performance of the ALD-coated BTS powders and pellets are characterized. It is revealed that electrical conductivity and thermal conductivity are decoupled, and thus, zT of ALD-coated BTS pellets is increased by more than 60% compared to that of the uncoated BTS pellets. This result can be utilized in a novel method for improving the thermoelectric efficiency in materials processing.