연폭로 근로자들에서 적혈구 Pyrimidine 5'-Nucleotidase 활성도 및 요중 N-Acetyl-β-D-Glucosaminidase 활성도와의 상관관계 연구

서홍규,이병국,황천현,장성훈,이성수,이원진,최재욱 大韓産業醫學會 1997 대한직업환경의학회지 Vol.9 No.2

In this study, we measured the activity of the erythrocyte pyrimidin 5'-nuclectidase(P5N) and urinary N-acetyl-β-D-glucosaminidase(NAG) from 154 workers exposed to lead and 43 workers not exposed. We analyzed the correlation of the P5N activity and NAG activity with other biololgical exposure indices of lead such as blood lead(PbB) and zinc protoporphyrin(ZPP). The measurement was performed by using high performance liquid chromatography(HPLC), spectrophotometer and atomic absorption spectrophotometer. The results are as follows : 1. The mean value of P5N activity for workers exposed to lead was 9.50±3.13 μmol uridine/hr/g Hb and 11.60±2.2 μmol uridine/hr/g Hb for workers not exposed. The P5N activity showed a normal distribution, but the other indices of lead showed logarithmic normal distributions. 2. The P5N activity and ZPP were decreased as PbB was increased. But the NAG activity had no correlation with changes of PbB. 3. The correlation coefficients of the P5N activity with other biological exposure indices of lead such as PbB, ZPP, NAG activity were -0.72, -0.55, and 0.05, respectively. We speculated that the P5N activity can be used as a reliable biological exposure index of lead but NAG activity can be used as a biological management index of lead.

Al-Si-Mg 주조합금의 저 사이클 피로거동에 미치는 미세조직의 영향

韓相元,金錫元 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.7

Low cycle fatigue tests were carried out using four kinds of Al-7%Si-0.4Mg cast alloys, i.e., two kinds of sand mold casts, permanent mold cast and semi-solid die cast. They were heat-treated in the condition of under aging and over aging to investigate effects of precipitates on fatigue. All tests were conducted under axial plastic strain amplitude control. Stress level of cyclic hardening curves increased sensitively with needle like eutectic Si particle, refined grain size and dendrite arm spacing(DAS). In particular, the refined grain structure of under aged matrix was more effective encourager for cyclic hardening compared with DAS and eutectic Si particle size. After rapid increase in cyclic hardening during several number of cycles, the stress amplitude kept increasing steadily until fracture in under aged alloys strengthened by shearable G.P. zone. On the other hand, over aged alloys strengthened by non-shearable β' precipitates generated more drastic initial hardening and the stress amplitude reached the saturation state in quite early stage of the fatigue.

방향성 수지상정조직과 구상 셀조직을 갖는 Al-7%Si-0.4%Mg 주조합금의 일축 찢기특성

한상원,김석원 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.12

Tear resistance behaviors of Al-7%Si-0.4%Mg cast alloys were examined using Kahn-type tear test specimens which are distinguished DCC(directional continuous cast) consisting of a directional and ordinary dendrite structure with SLD(semi-liquid die cast) consisting of globular cells and fine grain structure. Restricted plastic deformation occurs near notch tip of semi-liquid die cast characterized by refinement of grain size. Popin for stress was exhibited in semi-liquid die cast but no pop-in was observed in DCC cast alloy. Tear resistance was evaluated by the energies required for crack initiation, UE_(i) and the crack propagation, UE_(p). An unit propagation energy, UE_(p) can be converted into critical stress intensity factor, K_(c), which in directional dendrite structure improves due to a high plane stress state over thickness-direction and the fracture surface of slant type.

주조용 알루미늄 합금의 피로

한상원,김석원 한국주조공학회 2002 한국주조공학회지 Vol.22 No.2

입자-구멍배위와 42Ca, 42Sc, 및 42Ti 원자핵의 에너지 스펙트럼

심숙이,김문원 公州大學校 基礎科學硏究所 1996 自然科學硏究 Vol.5 No.-

Shell-model calculations are performed to investigate the level structure in ??, ?? and ?? Nuclei. The shell model states are expressed for two-particle, particle-hole and three-particle one-hole configurations in terms of coupled two-particle states. We have used the modified surface-delta interaction, pairing and Coulomb interaction in this calculation. The configurations considered are ??, ?? and Single-particle energies and parameters of the interaction are determined by least-squares fitting procedure. The resulting two-body matrix elements are applied to calculate the energy spectra of two-particle states and three-particle one-hole states in ??, ?? and ?? Nuclei.

백서 부분적 설절제가 하악골 성장에 미치는 영향에 관한 실험적 연구

현석환,김광원 대한치과교정학회 1995 대한치과교정학회지 Vol.25 No.5

이 연구의 목적은 부분적 설절제가 백서 하악골의 성장에 미치는 영향을 규명하기 위함이다. 생후 4주령의 웅서백서를 두 집단으로 분류하였다. 첫번째 집단은 대조군으로 사용하고 두번째 집단은 부분적으로 설절제를 시행한 집단이다. 이 실험동물은 부분적인 설절제 후 4주와 8주에 희생되었다. 부분적인 설절제 후 쥐의 하악성장변화는 건조 골표본에 의해 관찰되었다. 이 연구로부터 얻어진 결과는 다음과 같다. 1. 성장기 백서의 설절제는 하악골 자체의 형태에는 영향을 미치지 못하였으나 전반적인 하악골 성장의 감소를 초래했다. 2. 하악골 성장에 영향을 미치는 여러가지 요인 중 설은 백서 하악골 성장에 필수적인 요소이다. 3. 부분적인 설의 절제는 백서의 전체적인 성장을 변화시키지는 않았다. The purpose of this study was to investigate the effect of the partial glossectomy on the mandibular growth of growing rats. Thirty one Sprague-Dawley rats four weeks old were divided into two groupes : the first group served as the control and the second group was partially excised in the tongue of the rats. The experimental animals were sacrificed at 4 and 8 weeks after partial glossectomy. The changes of the rat mandibular growth following partial glossectomy were observed biometrically from dry bone specimens. The findings were as follows : 1. Partial glossectomy of growing rat produced inhibitory effects on the growth of the mandible and did not change the original shape of the mandible. 2. Among the factors affecting mandibular growth, the presence of the proper tongue size was essential. 3. Partial glossectomy of the growing rats could not change general growth of the rats whole bodies.

코스틱스법에 의한 순수 전단장치 평가에 관한 연구

황재석,김원현,서정희 嶺南大學校 工業技術硏究所 1998 工業技術硏究所論文集 Vol.26 No.1

There are many experimental devices for pure shear test such as off-axis tension test pure shear test for Iosipescu conceptions. Arcan circular disk for Arcan conceptions and the general pure shear test and Hawong Iosipescu shear test(H.I.S.T.) etc.. Hawong Iosipescu shear test(H.I.S.T.) device is analyzed through caustics. It is assured that H.I.S.T. device is more effective than Iosipescu shear test(I.S.T.) device for the measurement of stress intensity factor from causic. It is known that H.I.S.T. device without notch is most effective as pure shear test device, between H.I.S.T. device and I.S.T. device for caustics, but H.I.S.T .device and I.S.T. devices are can be used ad pure shear test device

ADSL망에서 가입자 수에 따른 지연 시간 분석

이준혁,홍석원 명지대학교 산업기술연구소 2001 産業技術硏究所論文集 Vol.20 No.-

Asymmetric Digital Subscriber Line(ADLS) is considered as one of the promising technologies to provide high-speed Internet access to subscribers. The speed that subscribers can achieve in the ADSL access network varies depending on the various factors. One of the factors is the dimensioning of the access network which is determined by how many users are connected to one DSLAM. In this paper we describe the architecture of ADSL access network and network constituents, and explain two connection models and related protocols for Internet service provisioning. Then we establishes the simulation model where each subscriber connects to a remote server by HTTP connection and download a page on each request. In this paper we analyze the delay and link utilization depending on the number of subscribers, download file sizes, and server capacities. We use OPNET for simulation.

化學蒸着法에 의한 超硬合金 切削工具의 TiC 被覆에 關한 硏究

李五演,金錫元 全北大學校 1983 論文集 Vol.25 No.-

Machine cutting tool materials coated by means of he chemical vapor deposition process(CVD) have reached a remarkable field of application in industry because of their good wear resistance and high machining speeds. The CVD process of TiC coating on cemented tungsten carbide is a heterogeneous gas-solid reaction of TiCl_4 and CH_4 in H_2 as a carrier gas and it is deposited by two different reactions; such as substrate reaction and hydrocarbon reaction. The primary object of the present work was to investigate the effect of reaction parameters; deposition temperature and partial pressure of CH_4 in gas mixtures on the growth rate of coating layer and wear properties of chemically vapor deposited TiC on WC+Co+TaC+TiC substrates. The experimental results obtained are as follows; (1) Each activation energy of substrate reaction and hydrocarbon reaction was found to be 14Kcal/mole and 81 K㎈/mole, respectively. (2) The growth rate of TiC coating layer was increased with an increase in deposition temperature and the concentration of hydrocarbon in reactant gas. (3) It is found that microhardness of TiC coating layer tents to increase with an increase in deposition temperature of CH_4 gas. The maximum microhardness value of coated specimen was observed to be Hv. 2800㎏/㎟. (4) The wear resistance of coates specimen was remarkably increased and exhibited superior cutting performance when compared with uncoated specimen.

차세대 인터넷 백본망을 위한 IP over SONET/SDH 기술의 분석

박준현,홍석원 明知大學校 産業技術硏究所 1999 産業技術硏究所論文集 Vol.18 No.-

This paper explains the IP over SONET/SDH that becomes nowadays one of the compelling candidates for building the next generation IP backbone networks. First, we introduce the protocol stack and the related protocols of IP over SONET/SDH and explain the new scrambling technique using 1+X scrambler since the legacy scrambler could be vulnerable by malicious users. And we compare the IP over SONET/SDH with the IP over ATM that has long been a strong candidate for future IP backbone networks and we recommend that the optimal choice for the IP backbone should be considered based on the merits and demerits of each technology. Additionally, the WDM technology that would be a substitute for SONET/SDH in the future is introduced in relation to the IP over SONET/SDH.