Micro Droplet Cell을 이용한 국부부식 저항성 평가

金熙山,金星猷 弘益大學校 産業技術硏究所 2005 産業技術 Vol.15 No.-

Mechanical and corrosion properties of 316L stainless steels are degraded with residual δ-ferrite and super ferritic stainless steels containing 30% Cr and 4% Mo are degraded with precipitation of secondary phases such as sigma phase when exposed to temperature of 600℃~820℃. However, the effect of residual δ-ferrite and sigma phase on corrosion resistance is not clearly understood. In this study, the effect of residual δ-ferrite and sigma phase on the localized corrosion in type 316L stainless steels and super-ferritic stainless steels containing 30% Cr and 4% Mo, respectively was examined with an micro droplet techniques and surface analysis. Type 316L stainless steels with δ-ferrite phase have higher passive and active peak current. In addition, the super-ferritic stainless steels with sigma phase have higher corrosion rate in passive zone. The details in mechanisms were described in the paper.

한국인 영어학습자와 영어원어민의 영어모음 발음 분석

구희산,오연진 中央大學校 韓國敎育問題硏究所 2001 韓國敎育問題硏究所論文集 Vol.- No.16

The purpose of this experimental thesis is to distinguish the differences in the way they produce vowel sound between Korean learners of English and English native speakers through acoustic phonetical experiment. To find out the distinctive features of English vowels that Americans and Koreans Pronounce, formant frequencies in spectrograph were measured. For the experiment. 3 Americans and 6 Koreans recorded their vowel pronunciation in sentences with minimal pairs. The result shows that Koreans usually move their tongue not as wide as Americans do. This may have caused by the language transfer. Moreover Americans pronounce back vowels longer while Koreans make front vowel sound longer. The reason for that is Americans use their tongue root more actively than Koreans.

언어와 민요의 운율 자질에 관한 음향음서학적 연구 : 중부 방언과 경기 민요를 중심으로

구희산 한국음성과학회 2003 음성과학 Vol.10 No.3

The purpose of this acoustic experimental study was to investigate interrelation between prosodic features of Korean spoken language and those of Korean folk songs. The words of Changbutaryoung were spoken for analysis of spoken language by the female graduate students and the song was sung for musical features by three Kyunggi Minyo singers. Pitch contours were analyzed from sound spectrogram made by Pitch Works. Results showed that special musical voices (breaking, tinkling, vibrating, etc.) and tunes (rising, falling, level, etc) of folk song were discovered at the same place where accents of spoken language came. I appeared that, even though the patterns of pitch contour were different from each other, there was positive interrelation between prosodic features of Korean spoken language and those of Korean folk songs.

영어 낱말 강세 규칙의 활용

구희산,이순향 中央大學校 韓國敎育問題硏究所 1996 韓國敎育問題硏究所論文集 Vol.- No.11

This article suggests a set of revised English stress rules which English teachers can apply in class. The revised rules are drawn from the word stress rules by chomsky & Halle, Kreidler and Liles. The rules are as follows: Condition 1. If the noun has the last lax vowel, the rule is applied to the rest of the noun except the last syllable. Condition 2. The suffix of a word, as -ly, -ment, -hood, -ing, cannot change the stress of root Rule 1. place stress on the last tense vowel of a word Rule 2. Place stress on the last vowel of a word if it is followed by a cluster of two or more consonants. Rule 3. Place stress on next to the last vowel of a word if neither of the above conditioon is met. The rules can help English teachers easily predict where the primary stress is placed in simple words and words with affixes.

음향 실험을 통한 영어 모음 발음교정

구희산,김옥경 中央大學校 韓國敎育問題硏究所 2000 韓國敎育問題硏究所論文集 Vol.- No.15

The purposes of this study are to measure and analyse the formant frequency of English vowels pronounced by Korean, and compare with that of English speakers and find the differences of English vowel pronunciation between Korean and American English speakers. At first the definitions of the formant frequency on sound spectrogarm were explained according to the theory of some phoneticians and phonologists. Next we carried out the experiment with selected four Korean women living in Seoul and Kyeonggi Province. We analysed their formant frequency of English vowels /i. I. æuv?α?∂/ with Pitch Works, and as a result, we found that there were differences of English vowel formant frequency between Koreans and American English speakers. In conlusion, we realized the reason of the differences, and suggested the ways that could reduce the differences and enable Koreans to pronounce English vowels similar to those of American English speakers.

영국영어와 미국영어의 모음 조직 비교

구희산 中央大學校 韓國敎育問題硏究所 1993 韓國敎育問題硏究所論文集 Vol.- No.8

The purpose of this article is to describe the characteristics of the vowel systems between British English and American english. British English is characterized by the loss of "r" finally and before consonant, as in mother and bird the rounded vowel in words like stop and pot. and the use of the broad "a" [?] in ask, path, grass, etc. american english, on the other hand, is characterized by the retention of a strong "r" in all position, the use of the flat "a"[?} in words like sat and ask, and the unrounded vowel in stop, lot, etc. Both English dialects also have some different characteristics in diphthongs.

C.V.D. 방법에 의한 Cd_0.78Zn_0.22 S박막 성장과 광전기적 특성연구

유상하,이상렬,홍광준,서상석,김혜숙,전승룡,윤은희,문종대 조선대학교 기초과학연구소 1993 自然科學硏究 Vol.16 No.1

We had grown Cd_0.78Zn_0.22S polycrystal thin films on slide substrate using chemical vapour deposition(CVD) method. We measured X-ray diffraction patterns in order to study Cd_0.78Zn_0.22S polycrystal structure. We studied its band gap using transmission curves and photocurrent and also analyzed photoluminescence using configurational coordinate model. We measured Hall effect·on this sample by Van der Pauw method and studied on carrier density and mobility depending on temperature.

재부동태 속도를 이용한 스테인리스강의 응력부식 민감성 예측

金熙山,金星猷 弘益大學校 産業技術硏究所 2004 産業技術 Vol.14 No.-

The recent development of method analyzing repassivation rate using a rapid scratch test and high field conduction model in which log i(t) is proportional to 1/q(t), makes it possible to predict SCC susceptibility more quantitatively, as well as to conduct the test more easily from the viewpoint of cost and timesaving. Since scratched surface is affected by the shape of scratching tip as well as mechanical properties, the inconsistency of scratched surface area having significant influence on the analyzed repassivation rate causes it difficult to distinguish the repassivation rates with a little difference. The validity of the proposed test was confirmed by examination of the effect of the alloy elements(W, Ni) on the repassivation rates of ferritic stainless steels obtained from both rapid scratch tests and the proposed tests.

모음 길이에 미치는 자음 환경의 영향

구희산 한국음성과학회 1998 음성과학 Vol.4 No.1

The purpose of this preliminary study on Korean vowel duration was to find how different syllable types and kinds of plosives influence vowel duration. The vowel duration of the Front Mid and Low vowel (/ε/(에), /??/(어), /??/(애), /a/(아)) was found to be longer than tha of High and Back vowels (/i/(이), /i/(으), /u/(우), /o/(오)). Compared with signal vowels (V), Vowels followed by a consonant (CV) were shortened by 79.3% and vowels between consonants (CVC) were shortened by 38.5%, respectively. These results suggest that types and the manner or place of articulation. Keywords: vowel, consonant, duratin

중압 배전망에서의 전력선 통신을 위한 OFDM 기법의 성능 분석

임장규,김산해,장희동,이원철,신요안 崇實大學校 生産技術硏究所 2002 論文集 Vol.32 No.-

Recently, PLC (Power Line Communication) on medium voltage power lines have been gaining much attention for high data rate access networking. In this paper, we evaluate the performance of OFDM (Orthogonal Frequency Division Multiplexing) schemes on medium voltage power line channels in the frequency range up to 20 ㎒. We analyze fading characteristics of multi-path channel models for medium voltage power lines, and simulations have been carried out for the OFDM using adaptive bit loading scheme. Simulation results indicate that the OFDM schemes with the adaptive bit loading show good bit error rate performance under harsh medium voltage power lines channel.